Incompatible Building Materials - SCHL

R esearch Report 

incompatible building materials 

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(outside Canada call 613 748-2003) 

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Incompatible Building Materials 

A report documenting premature failure in residential 

construction resulting from material incompatibility 

Canada Mortgage and Housing Corporation 

June 2003 

Prepared by: 

J.F. Burrows Consulting 

For: 

Policy and Research Division, 

Canada Mortgage and Housing Corporation 

CMHC offers a wide range of housing-related information, For details, call 1 800 668-2642 

or visit our Web site at www.cmhc.ca 

Cette publication est aussi disponible en français sous le titre : Matériaux de construction incompatibles 

Rapport sur la défaillance prématurée de bâtiments résidentiels découlant de l’incompatibilité de matériaux 

de construction, 63264

This research project was (partially) funded by Canada Mortgage and Housing Corporation (CMHC). The contents, 

views and editorial quality of this report are the responsibility of the author(s) and CMHC accepts no responsibility for 

them or any consequences arising from the reader's use of the information, materials and techniques described herein. 

National Library of Canada cataloguing in publication data 

Main entry under title: 

Incompatible building materials: a report documenting premature 

failure in residential construction resulting from material incompatibility 

Issued also in French under title: Matériaux de construction incompatibles. 

ISBN 0-662-34596-7 

Cat. no. NH15-411/2003E 

1. Building failures. 

2. Building materials. 

3. Buildings – Specifications. 

I. Canada Mortgage and Housing Corporation. 

TH441.I52 2003 691 C2003-980237-X 

© 2003 Canada Mortgage and Housing Corporation. 

All rights reserved. No portion of this book may be reproduced, stored in a retrieval system or transmitted in any form 

or by any means, mechanical, electronic, photocopying, recording or otherwise without the prior written permission of 

Canada Mortgage and Housing Corporation. Without limiting the generality of the foregoing no portion of this book 

may be translated from English into any other language without the prior written permission of Canada Mortgage and 

Housing Corporation. 

Printed in Canada 

Produced by CMHC

Note to users 

This report documents and shares information about building material incompatibilities. 

It opens with a “Quick Reference Guide to Incompatibilities.” The Quick Reference Guide is a fast 

and easy way to find out if a material is incompatible with other materials. 

Appendix B, page 48, is the survey form that was CMHC used to solicit incompatibility reports for 

this document. We encourage you to share your experience with additional incompatible building 

materials by completing the survey and returning it to CMHC. 

The text of this document is also available on-line, at the CMHC Web site, at www.cmhc.ca. 

i

Table of Contents 

Quick reference guide to incompatibilities.....................................................1 

Executive Summary ........................................................................................5 

Introduction ...................................................................................................7 

Purpose.....................................................................................................................................7 

Criteria for inclusion ................................................................................................................7 

Research intent and accuracy ....................................................................................................7 

Causes of material incompatibility............................................................................................8 

Methodology ............................................................................................................................9 

Advisory committee............................................................................................................9 

Research..............................................................................................................................9 

Survey...............................................................................................................................10 

Screening ..........................................................................................................................10 

Verification .......................................................................................................................10 

Report ..............................................................................................................................10 

Communication plan..............................................................................................................11 

Trend analysis .........................................................................................................................11 

Examples of Incompatibility .........................................................................13 

Division 1–General Requirements....................................................................................13 

Division 2–Sitework .........................................................................................................13 

Division 3–Concrete.........................................................................................................14 

General information .........................................................................................................14 

3.1.1 Concrete/Steel (ferrous metal) .................................................................................14 

3.1.2 Concrete/non ferous metals .....................................................................................14 

Division 4–Masonry .........................................................................................................15 

Division 5–Metals.............................................................................................................16 


Types of protection...........................................................................................................18 

Other metal-related reports.....................................................................................................19 

5.1.1 Copper tubing/Aggressive soils ................................................................................19 

5.1.2 Copper pipe/Plumbing............................................................................................20 

5.1.3 Copper flashing/Metal fasteners...............................................................................20 

5.1.4 Metal strapping seismic restraint/Hot water heaters.................................................21 

Division 6–Wood and Plastics..........................................................................................22 

Other wood - related reports ............................................................................................22 

6.1.1 Metal Fasteners/Cedar, redwood and treated wood products in exposed locations...22 

Division 7–Thermal moisture protection .........................................................................23 


7.1 Envelope...........................................................................................................................23 

7.1.1 Housewrap/Surfactants............................................................................................23 

7.1.2 Exterior membranes/Sunlight ..................................................................................23 

7.1.3 Peel-and-stick membranes/Vinyl windows ...............................................................24


7.1.4 Vinyl siding/Rigid insulation...................................................................................24 

7.2 Roofing.............................................................................................................................24 

7.2.1 Bituminous membranes/Polyisocyanurate foam insulation ......................................24 

7.2.2 Bitumens/Polystyrene foam insulation.....................................................................26 

7.2.3 EPDM membranes/Bituminous-based air barrier membranes and flashings............26 

7.2.4 Roofing membranes/Heat-applied roofing products ................................................26 

7.3 Sealants.......................................................................................................................26 


7.3.1 Sealants/Rigid insulation .........................................................................................28 

7.3.2 Sealants/Vent pipes ..................................................................................................29 

7.3.3 Silicone sealants, acid-cure/Other materials .............................................................30 

7.3.4 Silicone sealant/Mirrors ...........................................................................................30 

7.3.5 Silicone sealants/General..........................................................................................30 

7.3.6 Plumbers putty/Sunlight..........................................................................................31 

7.3.7 Polyurethane sealant/Polyethylene ...........................................................................31 

7.3.8 Polyurethane sealant/Asphaltic materials..................................................................32 

Division 8–Doors and windows .......................................................................................33 

Division 9–Finishes ..........................................................................................................34 

9.1 Coatings ...........................................................................................................................34 


9.1.1 Paint/Wood knots....................................................................................................35 

9.2 Flooring, resilient..............................................................................................................36 

General information: ........................................................................................................36 

9.2.1 Resilient flooring/Concrete sub-base........................................................................36 

9.2.2 Resilient flooring/Wood panel sub-floor ..................................................................36 

9.2.3 Resilient flooring/Floor fills and toppings................................................................37 

9.2.4 Resilient flooring/Latex-backed rugs and mats.........................................................37 

Division 10–Specialties.....................................................................................................38 

Division 11–Equipment ...................................................................................................38 

Division 12–Furnishings ..................................................................................................38 

Division 13–Special construction.....................................................................................38 

Division 14–Conveying systems .......................................................................................38 

Division 15–Mechanical...................................................................................................39 

15.1 High-temperature vent pipes/Combustion gas..........................................................39 

Division 16–Electrical ......................................................................................................40 

16.1.1 Smoke alarms/Halogen lighting.............................................................................40 

16.1.2 Electrical wiring/CPVC pipe .................................................................................40 

Trend Analysis...............................................................................................41 

Education ...............................................................................................................................41 

Sealants...................................................................................................................................41 

Builder awareness....................................................................................................................41 

Uses of materials.....................................................................................................................42


Instruction labels ....................................................................................................................43 

Trend summary ......................................................................................................................43 

Building Code Issues .....................................................................................44 

Appendix A: Research Sources.......................................................................45 

Industry associations...............................................................................................................45 

Architectural associations........................................................................................................45 

Government and regulatory bodies.........................................................................................46 

Research and university ..........................................................................................................46 

Publications ............................................................................................................................46 

Periodicals...............................................................................................................................47 

Appendix B: Survey .......................................................................................48 

Acknowledgements .......................................................................................49 

Advisory committee................................................................................................................49 

Technical reviewers .................................................................................................................49 

Survey respondents .................................................................................................................49

Quick reference guide to incompatibilities 

This Quick Reference Guide lists materials that may be incompatible when used with another 

material or materials. The materials are arranged in alphabetical order and the reference code directs 

the reader to the Division with details about the incompatibility. 

Using the Quick Reference Guide 

Name of 

material 

Division Number 

and name of 

incompatible 

material 

Page 

number 

Polyurethane 

7.3.7 Polyurethane sealant/Polyethylene–31 

When you want to find if a material is incompatible with other materials, find the name of the 

material in the bold names in the following alphabetical list. 

The line or lines under the name gives, first, the Division Number and report number, then the 

materials that are incompatible and then the page number where you will find complete 

information. 

1


Air barrier 

7.2.3 EPDM 

membranes/Bituminousbased 

air barrier 

membranes and 

flashings–26 

Alarms, smoke 

16.1.1 Smoke alarms/Halogen 

lighting–40 

Asphaltic materials 

7.3.8 Polyurethane 

sealant/Asphaltic 

materials–32 

Bitumens 

7.2.2 Bitumens/Polystyrene 

foam insulation–26 

7.2.3 EPDM 


air barrier 

membranes and 


Bituminous membranes 

7.2.1 Bituminous 

membranes/Polyisocyanurate 




Concrete 

General Information–14 

3.1.1 Concrete/Steel (ferrous 

metal)–14 

3.1.2 Concrete/Non-ferrous 

metals–14 

9.2.1 Resilient 

flooring/Concrete subbase–36 

Coatings 


9.1.1 Paint/Wood knots–35 

Combustion 

15.1.1 High-temperature vent 

pipes/Combustion–39 

Copper flashing 

5.1.3 Copper 

flashing/Metal fasteners–20 

Copper pipe 

5.1.1 Copper tubing/Aggressive 

soils–19 

5.1.2 Copper 

pipe/Plumbing–20 

CPVC pipe 

16.1.2 Electrical wiring/CPVC 

pipe–40 

Electrical 


lighting–40 


pipe–40 

EPDM membranes 

7.2.3 EPDM 


air barrier 

membranes and 


Exterior membranes 

7.1.2 Exterior 

membranes/Sunlight–23 

7.1.3 Peel-and-stick 

membranes/Vinyl 

windows–24 

Fasteners 

5.1.3 Copper 


6.1.1 Metal fasteners/Cedar, 

redwood and treated wood 

products in exposed 

locations–22 

Flashing, copper 

5.1.3 Copper 


Floor fills and toppings 

9.2.3 Resilient flooring/Floor 

fills and toppings–37 

Flooring, resilient 


9.2.1 Resilient 

flooring/Concrete subbase–36 

9.2.2 Resilient flooring/Wood 

panel sub-floor–36 



9.2.4 Resilient flooring/Latexbacked 

rugs and mats–37 

Foam insulation 






Halogen lighting 

16.1 Smoke alarms/Halogen 

lighting–40 

Hot water heaters 

5.1.4 Metal strapping seismic 

restraint/Hot water 

heaters–21 

Heat 

7.2.4 Roofing 

membranes/Heat-applied 

roofing products–26 

15.1 High-temperature vent 


Housewrap 

7.1.1 Housewrap/ 

Surfactants–23 

Insulation, rigid 

7.1.4 Vinyl siding/Rigid 

insulation–24 

2





7.3.1 Sealants/Rigid 


Latex-backed rugs and mats 



Lighting 


lighting–40 

Mechanical 

7.3.2 Sealants/Vent pipes–29 

15.1.1 High-temperature vent 

pipes/Combustion gas–39 

Membranes, bitimunous 




Membranes, EPDM 

7.2.3 EPDM 


air barrier 

membranes and 


Membranes, exterior 


membranes/sunlight–23 



windows–24 

Membranes, peel-and-stick 



windows–24 

Membranes, roofing 

7.2.4 Roofing 



Metals 



metal)–14 

3.1.2 Concrete/non-ferrous 

metals–14 

5.1.1 Copper tubing/Aggressive 

soils–19 

5.1.2 Copper pipe/ 

Plumbing–20 

5.1.3 Copper flashing/ Metal 

fasteners–20 



heaters–21 

Mirrors 

7.3.4 Silicone 

sealant/Mirrors–30 

Nails 





Paint 



Peel-and-stick membranes 



windows–24 

Pipe, CPVC 


pipe–40 

Plumbing 

5.1.2 Copper pipe/ 

Plumbing–20 

Polyethylene 


sealant/Polyethylene–31 



Polyisocyanurate foam 

insulation 




Polystyrene foam insulation 



Polyurethane 






Reinforcing steel 

3.1.1 Concrete/steel (ferrous 

metal)–14 

Resilient Flooring 


9.2.1 Resilient flooring/ 

Concrete sub-base–36 







Rigid insulation 

7.1.4 Vinyl siding /Rigid 







3


Roofing 

7.2.1 Bituminous membranes/ 

Polyisocyanurate foam 




7.2.3 EPDM 


air barrier 

membranes and 


7.2.4 Roofing 



Screws 





Sealants 




7.3.2 Sealants/Vent pipes–29 

7.3.3 Silicone sealants, acidcure/Other 


7.3.4 Silicone sealant/ 

Mirrors–30 

7.3.5 Silicone sealants/ 

General–30 

7.3.6 Plumbers putty/ 

Sunlight–31 






Seismic restraint 



heaters–21 

Siding 



Silicone sealants 

7.3.4 Silicone 

sealant/Mirrors–30 

Smoke alarms 


lighting–40 

Steel (ferrous metal) 


metal)–14 

Sunlight 


membranes/Sunlight–23 

Surfactants 

7.1.1 Housewrap/ 

Surfactants–23 

Vent pipes 

7.3.2 Sealants/Vent pipes 29 

15.1 High-temperature vent 


Vinyl siding 



Water heaters 



heaters–21 

Windows, vinyl 



windows–24 

Wiring 


pipe–40 

Wood 



Wood panel sub-floor 



Wood, treated 





Wood, cedar and redwood 





Wood knots 


4

Executive Summary 

There have long been suspicions that the dramatic increase in the number of products and 

materials available for residential construction could result in a far greater incidence of failure due 

to material incompatibility. The combination of incompatible materials can result in deterioration 

of one or both materials, reducing service life and resulting in additional cost, and causing 

inconvenience or performance degradation for both builders and homeowners. 

Although incidences of incompatibility surfaced from time to time, they were often lost because 

there was no central registry for the recording of material combinations to be avoided. Canada 

Mortgage and Housing Corporation (CMHC) initiated a study to research and document examples 

of building material incompatibilities. The purpose of this research report is to document and share 

information that will help builders, renovators and homeowners avoid unnecessary cost and 

inconvenience. 

An Advisory Committee comprised of respected building experts representing building officials, 

the residential construction industry, government and university research sectors and the wood 

and coating manufacturing industries guided the project. The purposes of the committee were to: 

a) guide the project by defining the scope and direction, 

b) provide input to the project based on experience and knowledge, and 

c) assist with the wide distribution of the information at the end of the project. 

Extensive research was done to uncover examples of incompatible building materials. Relevant 

periodicals, textbooks and Web sites were reviewed and major universities and research facilities 

specializing in building materials were contacted. A survey form was distributed to builders, 

renovators, architects, specification writers and code officials through their professional associations. 

Once the raw data was collected, the examples were screened and reviewed by the Advisory 

Committee. Prior to incorporation in the report, each reported case of material incompatibility 

was reviewed by a technical expert to ensure the validity of the information in the report. 

This report documents 35 examples of building material incompatibilities that can result in 

shortened service life, material or system failure, and in some cases, compromise health and safety. 

A review of the examples reported shows that some are old problems (for example, dissimilar 

metals) that still occur as a result of lack of awareness or failure to foresee ramifications. Others 

examples of incompatibility are caused by new generation materials (for example, sealants) and may 

occur because of the wide range of chemical formulations of these products and the wide range of 

materials they are used with. A simple, standardized labelling system would make it much easier for 

builders and renovators to make appropriate sealant selections. 

For each example documented in the report, there are likely several others that have not been 

reported. This report is a starting point for documenting building material incompatibilities. 

5

Introduction 

In the past 30 years, residential construction has become much more complex. In addition to the 

age-old purpose of providing shelter, residential building design needs to consider energy efficiency, 

using materials that minimize effect on the environment, waste reduction and more stringent code 

requirements for fire, durability, indoor air quality, sound transmission and moisture and mold 

control. 

This increase in complexity has been accompanied by a vast increase in the number of materials 

that help builders and renovators meet these increasing requirements. The wide range of possible 

combinations for building materials, finishes, furnishings and accessories means the chances of a 

problematic combination of building materials has increased. Innovation always has an impact and 

in some cases, the full ramifications of using new products are not completely understood. 

The Canadian Home Builders’ Association (CHBA) and CMHC have been aware of official and 

unofficial reports of suspected building material incompatibilities. However, because there has been 

no central registry for recording incompatibility problems, it is likely that many problems are not 

reported or recorded. This means there is no shared learning among building professionals and 

problem material combinations are repeated. 

The use of incompatible materials can result in deterioration of one or both materials, reduced 

service life, discoloration, or poor adhesion between materials. Technical literature that accompanies 

various construction materials and products may identify incompatibility issues, but such 

instructions are not always noted. In addition, where several trades are involved, compatibility 

issues may be overlooked at the interface of such components as windows, roofing, foundations, 

deck coatings and other elements where a number of materials and trades meet. 

Purpose 

The purpose of this research is to gather and document building material incompatibilities so that 

lessons learned in the field can be shared. Prior to this project, the lack of a central registry meant 

there was at best very limited sharing of information about lessons learned. Increased awareness 

of building material incompatibilities will reduce construction defects to the benefit of builders, 

renovators, designers, homeowners and material manufacturers. 

Criteria for inclusion 

Approximately 100 examples of incompatibility were uncovered through the literature search and 

the survey. Only 35 have been included in this report. At the outset of the project, efforts were 

made to define incompatibility for the purposes of the final report. It was determined that chemical 

interaction would be the main criteria for defining incompatibility and the report would be a 

starting point for describing the clearest and most obvious examples of material incompatibility. 

Accordingly, this report describes the major examples of incompatibility known to Canadian 

builders and renovators as of the first quarter of 2003. Examples that were not included in the 

final report were rejected if they: 

• could not be substantiated 

• were a duplicate of a case already in the report 

• violated generally accepted good practice 

7


Research intent and accuracy 

The purpose of this report is to caution builders about possible incompatibility issues that could 

arise if certain materials are combined in use. The report is based on concerted efforts to validate 

and confirm examples of incompatibility. In no way does this report purport to blame one material 

or another for any problems or alleged problems resulting from proven or suspected 

incompatibility. 

For this reason, CMHC and its agents and consultants provide the information in this report in the 

spirit of helping builders and renovators learn from each other’s experience so that they can avoid 

callbacks. The report may also serve to help manufacturers make product improvements in response 

to applications or circumstances that were not envisioned when a product was conceived. 

Causes of material incompatibility 

Some of the incompatibility cases reported are well documented scientifically. For example, it has 

long been known that the combination of two different metals will result in accelerated corrosion 

of one. The science of metallurgy is well advanced and the challenge is to inform builders so that 

problems can be avoided. This does not mean that one metal is better than the other–simply that 

precautions are necessary in cases where the use of two different metals cannot be avoided. These 

types of incompatibilities can usually be identified and substantiated by literature research. 

Other instances of incompatibility involve new products or applications of products that were 

not expected during product development and testing. Often, these incompatibilities are newly 

discovered and are reported by building professionals. In these cases, an incompatibility may not 

have gathered enough prominence for its effects to be replicated and documented scientifically. 

It is intended that the information in this report will be augmented, corrected, abridged and 

updated to include additional information as deemed appropriate. 

Physical incompatibilities can occur when materials react differently to temperature. For instance, 

if torch-grade roof membranes are installed over self-adhered or spray-applied membranes, the 

application heat may cause self-adhered or spray-applied membranes to melt. 

Chemical incompatibilities occur when adjacent materials react chemically. For example, the 

chemical composition of asphalt roof membranes may cause certain rubber membranes to 

decompose. 

Moisture, sunlight and temperature are factors that cause rot, corrosion, mold, degradation, loss 

of insulating capability, thermal movement, weakening, and distortion–all major focuses of building 

science research. These topics fall outside the definition of incompatibility as used in this report. 

However, there are indeed grey zones that could not be avoided. For example, the corrosion 

rate of one of two dissimilar metals is accelerated by moisture, temperature and salt-laden air. 

During the course of the project, attempts were made to differentiate between problems of 

incompatibility and those resulting from design and workmanship problems. For example, damp 

proofing is applied to concrete foundation walls to prevent transmission of moisture through the 

8


wall. Damp proofing is adequate for situations where there is not a hydrostatic head on the wall 

or to compensate for cracks in the concrete. While it might be said that damp proofing is not 

compatible with cracked concrete, it is compatible with concrete. Therefore, this report was 

considered to be a quality control issue rather than an issue of material incompatibility. 

There are many instances in construction where workers are advised to protect themselves from 

fumes, dust and chemicals. For example, exposure to VOCs (volatile organic compounds) emitted 

by solvent-based coatings during curing should be controlled. Instances of construction conditions 

that are health hazards have not been included in the scope of incompatible building materials. 

Builders are advised to take all manufacturers’ recommendations for health and safety precautions 

seriously. 

In some cases, incompatibility was reported for a specific trade-named product. In such cases, it 

was verified that a case applies to a family of products rather than a trade-name product before 

being included in the report. 

Methodology 

Advisory committee 

An Advisory Committee (see Acknowledgements, page 49) comprised of respected building experts 

representing building officials, the residential construction industry, government and university 

research sectors and the wood and coating manufacturing industries was established to: 

1. Guide the scope and direction of the project. 

2. Identify sources of information for incompatibility problems. 

3. Provide advice and assistance for getting the report information to building professionals. 

Research 

At the outset of the project, a literature search was made that included a comprehensive review of 

building and material sources of information. The search focused on Canada but U.S. sources were 

also searched. The search words used included: failure, degradation, delamination, incompatible, 

incompatibility, premature, deterioration and defect. 

The search covered the Internet, builder periodicals such as Fine Homebuilding and the Journal 

of Light Construction, literature searches made through the Canada Institute for Scientific and 

Technical Information (CISTI) and the Institute for Research in Construction of the National 

Research Council and correspondence with a number of industry associations such as the Canadian 

Home Builders Association and the National Association of Home Builders Research Center (see 

Appendix A, page 45). 

The literature search generated 10 of the 35 incompatibility examples that were incorporated into 

the final report. 

9


Survey 

A survey form was sent to architects, builders, renovators, building officials, industry associations 

and selected individuals to obtain examples of building material incompatibility. Respondents were 

asked to describe the material incompatibility problem and, where possible, a solution to the 

problem. In many cases, the person who reported the case was contacted for additional 

substantiating information. 

A sample survey form is located in Appendix B, page 48, for the purpose of: 

• documenting how the survey was made. 

• providing an avenue for readers to report additional incompatibility examples. 

• The survey generated 25 of the 35 examples that were incorporated in the final report. 

Screening 

Each example was screened to ascertain that the example fell within the meaning of incompatibility. 

The screening also determined whether additional confirmation was required or if an example was 

a duplicate of one already reported. The results of the screening were submitted to the Advisory 

Committee for approval. Prior to inclusion in the final report, examples were confirmed by 

a) published information and 

b) by one or more technical experts. 

In some cases, known incompatibilities resulted from combinations that are permitted by building 

codes. In such cases, the example was submitted to the appropriate code officials for review and 

action. 

Verification 

Each of the examples, including the General Information that accompanies some sections, was 

reviewed by a technical expert prior to incorporation into the report, to ensure the information 

is accurate. 

Report 

“Section 7–Examples of Incompatibility,” page 13, explains the nature of the material 

incompatibility problem, the time frame it takes for the problem to become apparent and, as much 

as possible, an explanation of why the materials are not compatible. Each item has a reference title 

and each item is explained in more detail in terms of Problem, Reporting source and Solution. 

In some cases, a General information section has been added where the problem is broad rather 

than specific. For example, dissimilar metals are known to be problematic especially when moisture 

is present. Because there are perhaps 20 or 30 metals that can find their way into residential 

construction, the General Information explains how the combination of metals can be satisfactory 

or unsatisfactory depending on much they differ chemically. 

10


The report has been organized based on the Masterformat numbering system. Each example, even 

though it involves two materials, is reported only in one location, but is cross-referenced to the 

other Division (if applicable). (The location of each example was selected to make finding the 

information as intuitive as possible for the reader–it is in no way intended to blame one material 

or the other.) 

For example, “7.1.3 Peel-and-stick Membranes/Vinyl windows” (page 24) is reported in “Division 

7–Thermal moisture protection,” page 23. There is also, in “Division 8–Doors and windows,” 

page 33, a reference to 7.1.3. 

Communication plan 

Toward the end of the project, a technology transfer plan was developed to provide the report 

to individuals and organizations that assisted with survey responses or technical review. The 

information on incompatibility will be available to a wide audience. Hopefully, distribution of 

the report will result in more incompatibility examples that can be added to future reports. In 

the longer term, the report might be available on the Internet and provide an online mechanism 

for adding additional examples of material incompatibility as they arise. The survey form in 

Appendix B, page 48, will be used to solicit additional examples of incompatibility. 

Trend analysis 

The examples reported were assessed as a whole to determine trends in terms of groups of materials 

that seemed particularly prone to incompatibility or lessons that could be learn from the reported 

examples. See Section Trend Analysis, page 41. 

11

Examples of Incompatibility 

This section describes the reported examples of incompatible building materials. 

Division 1–General Requirements 

No reports 

Division 2–Sitework 

No reports 

13


Division 3–Concrete 

General information 

Concrete is a versatile building material, the predominant choice for residential foundations and is 

finding increased use for the above-ground structure. Concrete, a proportioned combination of 

cement and aggregates, is chemically complex and care should be exercised in the embedment of 

metals in concrete. Steel reinforcing is the most common metal embedded in concrete and generally 

performs well, but special measures may be required for severe environments. 

Other concrete-related reports: 

Division 9–Finishes 9.2.1 Resilient flooring/Concrete sub-base (page 36) 

3.1.1 Concrete/Steel (ferrous metal) 

Problem: Steel is the most common reinforcement used in concrete and normally provides 

reinforcing steel with excellent corrosion protection. However, the deposition of de-icing salts on 

reinforced garage floors can result in corrosion of the steel. As the steel corrodes, it increases in 

volume and causes the concrete to spall. 

Reporting source: Literature search 

Solution: Concrete structures must be designed to suit the service conditions. For residential 

construction, conditions are not usually encountered that require special measures to ensure that 

steel corrosion does not damage the concrete. However, garage floors can be exposed to 

concentrations of de-icing salts that fall from vehicles. 

Corrosion of the reinforcing steel can be controlled if one of the essential elements (steel, oxygen, 

water, chloride) is unavailable for the galvanic process that causes the corrosion. In practical terms, 

this means 

a) coating the steel with a protective cover like epoxy 

b) minimizing the porosity of the concrete by using low water-cement ratio concrete 

c) providing a good slope and drains to remove salt and water from the surface 

d) using a coating or membrane covering to keep the salt solution away from the concrete surface, 

or 

e) ensuring an adequate concrete cover over the steel reinforcements. 

Although each of these measures can work, a combination of two or more increases longevity. 

3.1.2 Concrete/Non-ferrous metals 

Problem: The embedment of non-ferrous metals in concrete or mortar can lead to either failure of 

the metal or damage to the concrete. Embedded aluminum flashing, electrical conduit or structural 

members are subject to corrosion in concrete or mortar. The reaction between aluminum and 

concrete may cause expansion and cracking of the concrete or mortar. The presence of calcium 

chloride (de-icing salts) and moisture increases the reaction rate. 

14


Copper flashing is sometimes embedded in concrete or mortar or both. Embedded copper is 

relatively immune to reaction with alkalis in the concrete. However, leaching from rainwater may 

bring chlorides from the concrete in contact with the metal and result in corrosion and green 

discoloration or runoff. Copper does not react with dry, hardened concrete or mortar or both. In a 

similar vein, bronze and brass fittings used for radiant floor heating (hydronic) systems required 

protection from concrete (plastic sleeves, for example) while the concrete is curing. 

Lead corrodes when in contact with fresh concrete and/or mortar but the reaction ceases if the 

concrete has cured and stays dry. Corrosion of embedded lead flashing in mortar joints will usually 

result in the production of a lead oxide, a white discoloration. When lead is only partially 

embedded, corrosion occurs because the part of the strip exposed to the concrete has a different 

electrical potential than the section exposed to air. Gradual corrosion and disintegration of the 

embedded lead will result. 

Zinc is highly reactive with alkalis and will deteriorate to some degree upon contact with fresh 

concrete or mortar or both. The reaction is limited, due to a corrosive film that forms on the outer 

layer of the zinc. Zinc will not react with dry, seasoned concrete or mortar or both. Zinc corrosion 

may also occur when galvanized iron, in the form of flat or corrugated sheets and rebar, comes in 

contact with fresh concrete and/or mortar. Galvanized iron is coated with zinc, and will react with 

moisture and chlorides in the concrete and/or mortar and can result in cracking of the concrete or 

mortar or both. 


Solutions: Care is required in considering the embedment of non-ferrous metals in concrete, 

especially in wet conditions. 

• Aluminum Coating the aluminum with bituminous paint, impregnated paper or felt, plastic, 

or an alkali-resistant coating will prevent or sharply reduce the corrosion. 

• Copper Chloride admixtures should not be used in concrete if contact with copper is expected. 

• Lead The concrete-embedded portion should be coated with epoxy, varnish, asphalt or pitch. 

• Zinc Embedded galvanized iron should be protected with epoxy, varnish, asphalt or pitch. 

Division 4–Masonry 

No reports. 

15


Division 5–Metals 


Galvanic corrosion (also called “dissimilar metal corrosion”) is corrosion damage that occurs when 

two dissimilar materials are coupled in a corrosive electrolyte. When a galvanic couple forms, one of 

the metals in the couple becomes the anode and corrodes faster than it would by itself, while the 

other becomes the cathode (Figure 5.1). 

Figure 5.1: Corrosion of a cadmium plated washer in contact with 

a stainless steel screw 

Galvanic corrosion alters the surface, making it more susceptible to chemical reaction with 

the atmosphere. In extreme cases, the galvanic corrosion can cause serious mechanical and 

structural damage to the materials involved. Homebuilders may use metals in many different 

applications–metal roofing and siding, windows, framing, fasteners, ductwork, electrical systems 

and water and waste water piping systems. In addition, metals are important components of 

appliances, computers and furnishings. Metal failures -corrosion, oxidization or rusting–may 

result in inconvenience or callbacks, shorten service life and may even compromise safety. 

Therefore, a basic primer on the factors that cause metal failures and how to slow or stop 

deterioration is provided here. 

Any two different metals in contact can generate contact potential due to their differences in 

electrical conductivity, resulting in a galvanic reaction. In many applications, the reaction is 

minimal but in some cases, the deterioration of one of the two metals can be rapid. The speed 

of the reaction is dependent on two factors: 

16


a) the electrode potential of the two metals in the electrochemical series, and 

b) their surrounding chemical environment. 

In general, the further apart the materials are in the galvanic table, the higher the risk of galvanic 

corrosion. For example, installing copper (noble number 55) water piping through steel studs that 

are galvanized with zinc (noble number 4) results in strong galvanic action. For this reason, 

building codes require plastic grommets to keep the two metals apart. Conversely, the closer one 

metal is to another in the table, the more compatible they will be. 

Figure 5.2 is the galvanic table simplified to show only those metals that are likely to be present in 

residential construction. At the left of the figure are the active or anodic metals, the ones that are 

sacrificed when in contact with metals that have a lower “noble” number. Zinc, with a low noble 

number, is often used as a sacrificial (galvanic) protection for steel. As galvanic action progresses, 

the zinc is gradually sacrificed and for this reason, the thicker the zinc coating is, the longer 

galvanized steel will perform. For example, connecting metals with widely different electrical 

properties can lead to loss of electrical conductivity as one of the metals in the connection 

corrodes. For example, copper wire should not be connected to aluminum wire or fixtures. 

Figure 5.2: Noble numbers 

Environment is the second factor that affects the speed of the reaction. The effect of galvanic 

corrosion is increased in the presence of an electrolyte, such as water or a salt that act as a transfer 

medium for the electrons. For this reason, corrosion is a greater problem for exterior applications 

such as roofing, cladding, windows, doors and air conditioning units. However, water is also in 

17


contact indoors with water piping and anywhere where water leakage is a possibility, for examples, 

under washing machines or dishwashers. In addition, high humidity or condensation increases the 

potential corrosion problem. Here are two examples: 

1. Built-in galvanized rain gutters are reported to disintegrate after as little as 13 years exposure 

to west coast moisture and salt air. 

2. Asphalt-backed copper flashing installed at the base of brick veneer is reported to disintegrate 

after 25 years exposure to west coast moisture and salt air. 

De-icing salts are a major corrosion problem for concrete structures, such as bridge decks. Even 

around the house, de-icing salts can accelerate corrosion in places where salts are deposited by 

vehicles or foot traffic such as walkways, garage floors, thresholds and the underside of steel entry 

and garage doors. 

Types of protection 

There are several common methods of protecting metals (Table 5.1). 

Sacrificial protection 

Hot-dip galvanizing is the process of immersing the steel object to be protected in molten zinc. 

The thicker the zinc coating is, the longer the steel will be protected from corrosion. For example, 

it is estimated a 1.7-mil zinc coating exposed to the weather will last 18 years in a suburban 

application and a coating of 3.4 mils will last 30 years. However, thicker coatings are prone to 

spalling away from the metals they are intended to protect if the host metal has not been properly 

prepared (for example, by pickling). 

Electroplating is the deposition of a metallic coating on an object by immersing it in a solution 

that contains a salt of the metal to be deposited. Electroplated coatings may perform a protective 

function, as in the case of electroplated fasteners, or a decorative function, as in the case of plating 

a lower-cost metal with gold and silver. In general, electroplated nails and screws will have a thinner 

layer of sacrificial metal than the hot-dip process and therefore the life expectancy of the fasteners 

will be lower. 

Table 5.1: Metal protection techniques 

Protection method Strengths Weaknesses 

Paint Easy to apply, inexpensive Short life, easily damaged 

Grease, oil Inexpensive Short life, easily removed 

Corrosion resistance 

alloys (stainless steel, brass 

etc) 

Hot-dip galvanizing 

Electroplating 

Excellent protection when 

properly selected 

Long-term protection, readily 

available 

Inexpensive, readily available, 

moderate protection 

Expensive 

Changes thread dimensions on 

screws and bolts 

Easily damaged, not 

recommended for use with 

treated wood 

18


Coating Non-metallic coatings may be used to provide corrosion resistance. For example, epoxy 

coated rebar has become common in commercial construction and epoxy-coated screws are widely 

used for deck construction. Any coating (for examples, paint, oil, Teflon®, wire sheathing) that 

keeps oxygen away from metals will curtail corrosion for as long as the barrier remains intact. 

Other metal-related reports 

Division 3–Concrete 

• 3.1.1 Concrete/Steel (ferrous metal) (page 14) 

• 3.1.2 Concrete/Non-ferrous metals (page 14) 

Division 6–Wood and plastics 

• 6.1.1 Metal fasteners/Cedar, redwood and treated wood products in exposed locations (page 22) 

5.1.1 Copper tubing/Aggressive soils 

Problem: Copper is very resistant to deterioration in buried conditions. However, there are 

conditions that can cause copper to corrode when it is exposed to certain soils: 

• abnormally aggressive soils 

• stray AC and DC current in the ground 

• faulty design 

• galvanic reaction involving dissimilar materials. 

The soil conditions that result in copper corrosion are very complex and not entirely understood. 

However, corrosion is most often associated with: 

• Soils high in sulfate and chloride content and having a high capacity to retain water, and 

moderate to high annual rainfall (76 cm or 30 in. or more). 

• Soils that have large quantities of organic matter (particularly soils that contain organic acids 

or that support active anaerobic bacteria). 

• Most cinder fills, either because of the sulfides present or the galvanic action created by the 

carbon particles in the cinders. 

Soils such as clay, sand, gravel, loam, and chalk seldom possess the combination of properties 

associated with corrosion. 

Failures from poor design usually occur where bent copper tube passes through a concrete slab. If 

the pipe is carrying heated liquid, thermal stresses may cause fatigue and cracking on the underside 

of the tube at the underside of the slab. It is also known that copper embedded in concrete is 

normally cathodic in relation to copper embedded in soil. This can result in a weak galvanic 

reaction if water is present. 

19


Reporting source: This problem has been reported in the Journal of Light Construction and 

through Internet chat forums. 

Solutions: 

1. Use Type K (heavier wall) copper pipe recommended for underground use or use a sleeve. 

2. For aggressive soils, ensure trenches for copper pipe are not collectors for surface runoff or 

septic drainage systems. For those areas where the soils are known to be aggressive, the pipe can 

be encased in selective backfill. However, this method will be affective only if the drainage for 

the aggressive soils can be kept away from the pipe. Or, use polyethylene coated copper pipe. 

3. Use di-electric fittings for connection to non-copper pipes. 

4. For copper pipes carrying hot liquids that penetrate concrete slabs, allow for thermal expansion 

of the pipe below the slab or install the pipe in a sleeve. 

5.1.2 Copper pipe/Plumbing 

Problem: Copper tubing can also develop pinholes without being in contact with the soil. In the 

U.S., there are reports of indoor copper piping developing green spots on the outer surface followed 

by dripping from these locations. This problem has been reported in groups of houses less than 

10 years old. 

This internal corrosion is attributed to either aggressive water or the use of incompatible plumbing 

flux. The water is considered aggressive if the water has a pH value lower than 7.0 (acidic) and high 

levels of dissolved carbon dioxide and oxygen or sulphates. Acid water is known to be corrosive to 

copper–in fact, ANSI/NSF Standard 61 certifies copper for use only where the pH of the water is 

6.5 or higher. Although highly alkaline water pH (higher than 7.0) can also be corrosive, such 

water is so unpalatable it is rarely used as a water source. 

The problem could also result from the use of flux that is not as flushable as that stipulated in 

ASTM B-813. 

Reporting source: Journal of Light Construction, Internet chat forums, B.C. architect. 

Solution: This problem is rare and not yet well understood. It poses a dilemma–particularly for 

rural housing where the water chemistry is not controlled by a public utility. At this point, it is 

thought the occurrence of copper pipe pitting can be reduced by using the correct flux, not using 

an excessive amount of flux, flushing the pipe properly–for 10 minutes at full flow–after 

installation, and by not allowing pipes to sit idle for a long period of time before they are brought 

into regular use. 

5.1.3 Copper flashing/Metal fasteners 

Problem: Copper flashing fastened with non-copper fasteners is subject to galvanic action and 

corrosion. While galvanic corrosion is the most familiar type of metallic deterioration, it is the most 

neglected from the standpoint of anode/cathode area relationships. For example, galvanic corrosion 

can occur when two metals that are far apart in the electrochemical series (Figure 5.2 ) are 

20


combined in a moist, corrosive environment building assembly. When moisture is present, a 

galvanic cell is set up, causing the less-noble metal to corrode. This galvanic corrosion phenomenon 

is common in copper-aluminum roof assemblies. The aluminum (the less-noble material) fasteners, 

gutters and downspouts tends to be dissolved by the copper (the more-noble material) flashing on 

roofs. 

Reporting source: Trade associations and builders 

Solution: Use copper nails or screws for fastening copper flashings. 

5.1.4 Metal strapping seismic restraint/Hot water heaters 

Problem: For areas subject to earthquakes, the National Building Code stipulates that hot water 

tanks be restrained by strapping to prevent movement during an earthquake. Galvanic action 

between the tank and the strapping could negate the effectiveness of the strapping to restrain the 

tank in the event of earthquake. This is a specific example of dissimilar metals that could lead to 

structural failure. 

In one case, it was reported that seismic support strapping had corroded after 1 1/2 years due to 

galvanic reaction with an area of the hot water tank where the paint had been damaged. This may 

not be a common occurrence but shows how incompatibility can result not only in inconvenience 

or shortening of life span, but can also result in unsafe conditions. 

Reporting source: B.C. building official 

Solution: Either the strapping metal should be similar to the tank casing, or the two metals should 

be separated by covering the strapping with a sheathing material (garden hose was the solution 

suggested). 

21


Division 6–Wood and Plastics 

Other wood-related reports: 

• Division 9–Finishes 

• 9.1.1 Paint/Wood knots (Page 35) 

6.1.1 Metal Fasteners/Cedar, redwood and treated wood products in exposed 

locations 

Problem: Unprotected fasteners made of metals susceptible to corrosion should not be used with 

wood products treated with copper-based preservative (such as ACQ—ammoniacal copper quat, 

CCA–chromated copper arsenate and copper azole) in wet locations because the copper in the 

preservative will accelerate the oxidizing effect of water on the metal. In addition, types of wood 

that have natural resistance to decay, such as redwood and the cedars, contain natural chemicals 

that can also cause premature failure of nails and screws. Untreated fasteners and even lightlygalvanized 

fasteners suffer a loss of cross-section and ultimately fail. 

Reporting source: This incompatibility problem has been well documented in information 

produced by the Canadian Wood Council, Forintek Canada Corp. and the Canadian Institute for 

Treated Wood. 

Solution: In general, hot-dipped galvanized, coated fasteners recommended by the preservative 

manufacturer or stainless steel fasteners should be used with preservative treated wood. 

Building codes require that fasteners used for wood foundations be hot-dipped galvanized or 

stainless steel conforming to CSA B111, Wire Nails, Spikes and Staples. For cedar shingle or shake 

roofs and siding, the Western Red Cedar Lumber Association recommends the use of hot-dipped 

galvanized, aluminum or stainless steel fasteners. 

22


Division 7–Thermal moisture protection 


Moisture management is a very important aspect of building design and performance.Therefore, it 

is not surprising that a fairly large number of building material incompatibilities were reported for 

this division. 

There are many materials that are affected by heat (cold), moisture and ultraviolet light that have 

not been included in this section because their deterioration is affected by environmental 

conditions rather than by other building materials. 

7.1 Envelope 

7.1.1 Housewrap/Surfactants 

Problem: There are reports of changes in the properties of spunbonded polyolefins due to 

surfactants. The surfactants can originate from 

a) certain types of wood species 

b) additives mixed with the stucco to improve workability during installation. 

The primary function of a housewrap or sheathing membrane is moisture control. Therefore, any 

breakdown of the moisture penetration control barrier offers the possibility of water entry into the 

building envelope. 

Certain chemicals can cause the loss of water repellency of spunbonded polyolefin housewraps. 

These chemicals, called surfactants, are typically ingredients in soap.Surfactants can reduce the 

water repelling capability of housewrap by changing the viscosity of water. 

The tannins that make species such as cedar and redwood durable can also act as surfactants that 

cause housewrap to become more permeable to water. In addition, certain additives that improve 

the workability of stucco can also act as surfactants and lower the effectiveness of housewrap 

moisture barriers. 

Reporting source: Building science researchers, builders 

Solution: For wood species with high tannin content, install the cladding over strapping so that the 

cladding is not in direct contact with the housewrap. Another solution (probably less reliable) is to 

backprime the siding. 

For stucco, a building system that separates the stucco from the housewrap should always be used. 

7.1.2 Exterior membranes/Sunlight 

Problem: Building paper and housewraps are installed in wall assemblies to prevent rain 

penetration. Any breakdown of the rain penetration control barrier offers the possibility of water 

entry into the building envelope. Building papers and housewraps are not designed to withstand 

long-term exposure to ultraviolet radiation (sunlight). 

23


Therefore, the planning of construction should ensure that building paper or housewrap membrane 

be covered with cladding in the period of time recommended by the membrane manufacturer. In 

addition, prolonged exposure increases the potential of tears from wind and construction activity. 

Reporting source: Product evaluation reports 

Solution: All Canadian Construction Material Centre (CCMC) product evaluation reports verify 

sheathing membrane performance based on a 60-day exposure. However, because the durability of 

exposed housewrap varies with climate and exposure, it is good practice to cover the membrane 

soon after installation and to check the manufacturer’s recommendations. 

7.1.3 Peel-and-stick membranes/Vinyl windows 

Problem: Certain asphalt-based peel-and-stick membranes used to seal sheathing membranes to 

vinyl doors and windows may react with the vinyl. The reaction results in the asphaltic membrane 

running and staining exterior surfaces. The asphaltic material is a first generation peel-and-stick 

product (4-in.-100-mm and 6-in.-150-mm rolls). In addition to staining the vinyl, it is likely the 

reaction also damages the window or door frame. Staining shows itself within one year of 

installation. It is not known if or when failure of the joint will occur. 

Reporting source: B.C. architect 

Solution: Use new generation peel-and-stick products or use rubber products and check with the 

window manufacturer for compatibility. 

7.1.4 Vinyl siding/Rigid insulation 

Problem: Vinyl siding applied directly over EPS or XPS (expanded or extruded polystyrene) rigid 

insulation is a plastic-on-plastic arrangement. Vinyl siding has a high coefficient of expansion so, 

especially in the spring and fall, there is a lot of movement of the vinyl siding as temperatures 

fluctuate. The movement of the siding over EPS or XPS insulation causes squeaking noises that 

are audible through walls. 

Reporting source: Manitoba EPS manufacturer 

Solution: A layer of housewrap or building paper should be installed between the vinyl siding and 

the EPS or XPS insulation to isolate the materials. 

7.2 Roofing 

7.2.1 Bituminous membranes/Polyisocyanurate foam insulation 

Problem: This problem is reported for large, low-slope roofs but could apply to roofs on residential 

buildings. The National Roofing Contractors Association (NRCA) has reported incompatibility 

problems between hot-applied bituminous membranes. Although the vast majority of roof 

assemblies that include polyisocyanurate insulation have performed successfully, problems have 

been encountered that can result in some of the following failure modes: 

• facer-sheet delamination 

• cupping or bowing 

24


• shrinkage 

• crushing or powdering. 

It is not certain why the problem sometimes occurs, but it is thought that improper curing of the 

foam insulation board prior to installation makes it more prone to damage from the hot-applied 

bituminous membranes. 

Reporting source: The National Roofing Contractors Association (NRCA) Bulletin 2000-3, 

March 2000 

Solution: NRCA recommends that designers specify cover board over polyisocyanurate insulation 

in all low-slope membrane roof systems. The use of a cover board should help to reduce problems 

whether directly related to the manufacturing process or due to other causes. 

Insulation cover boards should be a minimum ½-in (13-mm) thick and be composed of any of the 

following: 

• glass-faced siliconized gypsum board 

• perlite board 

• wood-fibre board 

• glass-fibre board 

• mineral-fibre board 

When selecting a suitable cover board, designers should consider the characteristics of the specific 

roof assembly and take into account the cover board’s compatibility with the assembly. 

Using a suitable cover board over polyisocyanurate insulation in low-slope membrane roof 

assemblies provides the following benefits: 

• It separates the membrane from the polyisocyanurate insulation, reducing the possible effects of 

facer-sheet delamination, edge cavitation, cupping or bowing, shrinkage and crushing or 

powdering of the polyisocyanurate insulation. 

• It allows for installation of the insulation board layers with staggered board joints, a practice 

known to reduce stresses on the membrane and improve a roof assembly’s overall thermal 

performance. 

• It may be required to achieve a fire-resistance classification for a roof assembly. 

In addition, NRCA is seeking improvements to ASTM C 1289, Standard Specification for 

Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board including the establishment of 

a requirement for curing time prior to shipment, and changes in the standard’s values for 

compressive strength, dimensional stability and R value determination. 

25


7.2.2 Bitumens/Polystyrene foam insulation 

Problem: Bitumens and some adhesives can cause polystyrene insulation to disintegrate (see 7.3.1 

Sealants/Rigid insulation, page 28). Bitumens can also be destructive to single-ply roofing 

membranes. This incompatibility may occur where a new replacement roof abuts an older roof. 

Reporting source: B.C. architect, architectural journal 

Solution: With new and replacement roofing projects, it is important to ensure that polystyrene 

insulation is covered with an approved panel to keep it separate from bitumens and other solventbased 

materials. 

7.2.3 EPDM membranes/Bituminous-based air barrier membranes and 

flashings 

Problem: EPDM (ethylene-propylene-diene monomer) roofing membranes have been used 

successfully for the past 30 years on large flat and low-slope roofs. However, the EPDM membrane 

is prone to becoming brittle and cracking where it contacts bituminous-based membranes and 

flashings. This is most likely to occur at roof edges and parapet walls. 

Reporting source: Alberta architect 

Solution: Galvanized-metal transition flashing should be installed between EPDM membranes and 

any bituminous-based membranes and flashings. 

7.2.4 Roofing membranes/Heat-applied roofing products 

Problem: Torch-applied roofing materials can cause damage to peel-and-stick roofing membranes 

or to foam insulation. 

Reporting source: Alberta architect 

Solution: Keep heat away from non-heat resistant materials or shield the heat-sensitive materials 

from heat. 

7.3 Sealants 


A sealant is a material intended to inhibit the passage of air and water in joints where movement is 

expected. Ability to accommodate movement is the most important property of sealants. However, 

a sealant can only accommodate movement if it is able to adhere to the surfaces it is sealing. After 

movement accommodation and adhesion, hardness and resistance to weather are important 

considerations. 

Because there are so many types of sealants and because their use has become commonplace with so 

many different materials, a basic understanding of sealants will help avoid compatibility problems. 

Here are some basic guidelines for this complex family of building materials: 

26


• Low-movement capability sealants (3 to 5%) are 1-part oil-based or latex (acrylic). Mediummovement 

capability sealants (7 to 13%) are 1-part butyl or acrylic (solvent based). Highmovement 

capability sealants (15 to 25%) are 1- or 2-part polysulfide or urethane or silicone. 

• High-movement-capability sealants are more expensive and are used in demanding commercial 

and industrial applications such as for high-rise buildings and bridge deck sealants where 

accessibility is limited and the cost of failure is high. In addition to high movement capability, 

such sealants are usually longer lasting and stay flexible and adhere better than lower quality 

sealants. Generally, residential construction will entail low and medium movement capability 

sealants. 

• Silicone sealants provide good performance for residential applications. Builders should be 

aware that some manufacturers produce so-called “siliconized” sealants. These products contain 

a small fraction of silicone and therefore they do not provide the same good performance 

characteristics as true silicone sealants. A siliconized acrylic or siliconized butyl should be 

considered as having the same properties as ordinary acrylic or butyl sealants. 

• Some surfaces may require a primer in order to accept a certain sealant. Primers are not 

commonly available in the consumer market, and the consumers should choose those sealants 

that generally possess unprimed adhesion. Contractors can typically obtain needed primers and 

thus have a greater variety of sealants suitable to the various applications. 

• The durability of a sealant depends on the application conditions, the conditions in which the 

sealant will serve (temperature, UV radiation, wind, rain and atmospheric pollutants) and the 

suitability of the sealant for the materials to be sealed and the expected range of movement. 

A sealant should be selected that best suits the service conditions. 

• A caulk is an oil-based sealant that has relatively low movement capability, usually less than 

five per cent. 

• In general, silicone sealants are the most durable to heat and weathering and least amenable to 

painting. Silicone sealants can only be overtopped with another silicone sealant and cannot be 

painted. 

• Polysulfides and polyurethanes are not recommended for critical glazing applications where 

sealants are exposed to full sunlight. 

• Each manufacturer has different formulations so check compatibility for your most common 

applications. Then, select a group of sealants that suit your applications and stay with them. 

• Use Table 7.1 as a general guide for sealant selection. 

27


Table 7.1: Sealant compatibility and adhesion 

Sealant Type 

Substrate 

Aluminum, 

anodized 

Aluminum, 

mill finish 

Brick 

Lowmovement 

capability 

Oilbased 

(acrylic) 1-part 

Latex Butyl 

1-part 1-part 

Mediummovement 

capability 

x 

x 

Acrylic 

(solventbased) 

1-part 

Polysulfide 

1-part 

Polysulfide 

2-part 

High-movement capability 

Urethane 

1-part 

Urethane 

2-part 

x x x x 

Concrete x, p x, p 

x, p, 

I 

Glass 

x, p 

Metal, 

x 

x x x, p 

painted 

Stainless 

steel 

Steel, 

galvanized 

Stucco 

Wood, 

painted 

Wood, 

stained 

Wood, 

unfinished 

x x x, p 

x x x, p 

x, p x, p 

x, p, 

I 

x 

x, p x, p x x, p, 

I 

x x x x 

x x x x x x 

x x x x x x 

x x x x x x 

x, p 

x, p 

Silicone 

acid 

cure 

x 

x, p 

x 

Silicone 

neutral 

cure 

x 

x 

x 

x 

Silicone 

base 

cure 

x 

x 

x 

x 

x x x 

x x x 

x x x 

x, p x x 

x, p x x 

x x x 

x x x 

x x x 

Table Adapted with permission from: Cascade Sealants, Portland Ore 

Notes: x-likely good performance; p-primer needed; I, suitable for water-immersion application 

7.3.1 Sealants/Rigid insulation 

Problem: Solvent-based sealants (or adhesives) cause the degradation of polyethylene or polystyrene 

foam insulation. Sealant is sometimes used in the joints between panels to prevent the passage of air 

and water. Sealant is also used to provide air barrier continuity at the intersection of polystyrene 

and the air barrier material. Polystyrene panels may be attached to the structure with mechanical 

fasteners or, as in the case of attachment to concrete foundation walls, with adhesives. Usually, 

sealants and adhesives have different properties that do not make them interchangeable. 

There are two types of polystyrene (expanded and extruded) used for house insulation. Expanded, 

or moulded, polystyrene is commonly called beadboard and has a lower R value and is less 

expensive than extruded polystyrene because of its lower density. Both types of polystyrene 

insulation have the advantages of high R value, good moisture resistance, and high structural 

strength. 

28


The material safety data sheet from a major manufacturer notes that polystyrene is incompatible 

with aromatic hydrocarbons and other petroleum-based compounds. Silicones are typically 

compatible with polystyrene. However, the manufacturer stresses it is not a maker of sealants 

and adhesives and has no ability to control formulations. Therefore, it makes no specific 

recommendations for sealants and adhesives that are compatible with its polystyrene insulation. 

Reporting source: Material safety data sheet and other sources 

Solution: There are many types of sealants (Tables S1 and S2) and there are several types of sealants 

and adhesives that are not solvent-based. For residential construction, use latex (acrylic) butyl, 

silicone sealants or adhesives with polystyrene rigid insulation. 

7.3.2 Sealants/Vent pipes 

Problem: Manufacturers of Type B vents used for venting natural gas or liquid propane Category I 

appliances affix paper labels to the B-vent pipe sections to identify the type, size and code 

compliance for the pipe. 

Where the assembly pierces the roof, flashing is placed around the vertical pipe section and a storm 

collar is placed over this joint. To make the assembly watertight, the joint between the flashingstorm 

collar and the pipe requires the application of a flexible sealant. 

Because the paper labels are applied in random locations on the pipe and because the positioning 

of the protruding length of pipe within the flashing assembly depends on several factors, occasions 

arise where the paper label lies in the area that will be sealed (usually with silicone sealant). 

Although the seal may seem adequate at first, experience shows that the sealant bond at the paper 

label will quickly fail, allowing water to enter the roof through the B-vent assembly. 

Figure 7.1: Chimney label 

Sealant 

Storm collar 

Flashing 

29


Reporting source: B.C. construction management firm 

Solution: Installers should ensure that the paper label, including the adhesive, is removed prior to 

sealing if it is in the region to be sealed. In the longer term, this problem should be brought to the 

attention of vent manufacturers so that a non-problematic labelling system can be introduced. 

7.3.3 Silicone sealants, acid-cure/Other materials 

Problem: There are two types of silicone sealants–acid-cure and neutral cure. Acid-cure sealants 

contain acetic acid and cure by emitting the acid and give this family of sealants a vinegar-like 

smell. Acid-cure silicones are very economical, commonly available and adhere well to most 

surfaces. The acetic acid in these sealants is aggressive to many materials including epoxies, 

concrete, mortar, many types of fasteners and steel. 

Neutral-cure sealant cures by reacting with moisture in the air. They are typically slightly more 

expensive (10 to 50 %) than acid-cure silicones and do not adversely affect the materials that are 

susceptible to acid-cure sealants. 

Reporting source: B.C. window manufacturer 

Solution: There are many types and formulations of sealants (see Sealants–General Information, 

page 26). Have a basic understanding of the types of sealants, their strengths and weaknesses, and 

choose accordingly. 

7.3.4 Silicone sealant/Mirrors 

Problem: Silicone-based sealants and adhesives cause the degradation of the backing or mirrors 

in applications where mirrors are affixed to wall surfaces with acetic-cure silicone adhesives. 

The data sheet for this family of silicones states: 

“Not recommended for structural glazing or insulating glass glazing, concrete and stone expansion 

joints, horizontal decks, patios, driveway or terrace joints where abrasion is possible. Not 

recommended for surfaces with special protective or cosmetic coatings such as mirrors, reflective 

glass, Teflon-coated, polyethylene or polypropylene surfaces. Not recommended for use on 

concrete, marble, limestone, lead coated surfaces, submerged joints (swimming pools), plazas, 

decks, pavements.” 

Reporting source: Builders chat line. 

Solution: Do not use acetic-cure sealants or adhesives to affix mirrors. Use specially-formulated 

mirror mastics and take the usual precautions to ensure the surfaces to be joined are dry and clean. 

One maker of asphalt-based mirror mastic claims to make a product that gives “a strong permanent 

bond that remains flexible, yet absorbs movement caused by normal vibrations or thermal changes”. 

Neutral curing silicones have a good history of success in this application. However, in each 

situation the sealant manufacturer should be contacted to confirm suitability. 

7.3.5 Silicone sealants/General 

Problem: Silicone sealants are ideal for some applications, but there are some restrictions that need 

to be explained. 

30


• Painting–Silicone sealants do not hold paint and therefore they should not be used where 

painting is a requirement. 

• Re-sealing–Other types of sealants do not adhere to silicone sealant. Therefore, use only 

a silicone sealant over top an existing silicone sealant. 

• Ponding locations–Typically, a primer should be applied for sealants used in ponding locations, 

especially on concrete where a barrier primer is needed. 

7.3.6 Plumbers putty/Sunlight 

Problem: There is a wide range of methods used by electrical and mechanical trades for sealing 

electrical and gas service stub-outs for rooftop mechanical equipment. A lead sleeve is sometimes 

used by the roofer for the penetration through the roof membrane. Some mechanical installers 

crimp the lead sleeves and “temporarily” seal the penetration with electrical tape. Other installers 

pack plumbers putty between the cable and pipe penetrations and the sleeve, or in some cases, duct 

sealant is used. All these methods are temporary solutions that are not capable of withstanding the 

ultraviolet (sunlight) and temperature change of exterior locations. For example, plumbers putty 

is a linseed oil-based material inadequate for rooftop stub-out connections where vibration and 

weather exposure is extreme. After approximately one year, plumbers putty shrinks and becomes 

hard with no resiliency for movement. After approximately two to three years, it crumbles away 

from the joint leaving the sleeve and penetration exposed to weather and rain penetration. 


Solution: Remove existing putty, tape or other temporary sealants from electrical and mechanical 

stub-out joints. Plumbers putty and electrical tape commonly leave oil and residue that prevents 

good bonding for the permanent sealant. The surfaces to be sealed must be thoroughly cleaned 

with solvent and dried before the application of a high-performance polyurethane sealant. 

7.3.7 Polyurethane sealant/Polyethylene 

Problem: It is reported that (poly)urethane sealant does not adhere well to polyethylene sheet 

material. Although (poly)urethane sealants have excellent adhering properties in most cases, the 

adhesion to polyethylene films is very poor. In some installations, the sealant has delaminated after 

six months of service even though the adherence seemed good at the time of installation. 

There is normally very poor adhesion between (poly)urethane sealants and polyethylene sheet. For 

this reason, polyethylene is the most commonly used bond breaker behind (poly)urethane sealants 

(as well as other sealants). An initial adhesion occurs as a result of the contact of the sheet to a 

viscous liquid. Then as the sealant cures to a rubber and gets harder, the adhesion based on viscous 

fluid contact decreases. There are no chemical reactions between the (poly)urethane sealant and the 

sheet polyethylene and thus it is understandable that there is only mechanical adhesion and this is 

lost as the sealant continues to cure and harden. 


Solution: To maintain airtightness across air barrier joints, sealants must have a long service life 

without hardening or cracking with age and be compatible with adjoining materials. 

31


The CSA standard for the construction of permanent wood foundations stipulates the types of 

sealants used to seal the exterior polyethylene moisture barrier as follows: 

• CAN/CGSB-19.13 Sealing Compound, One Component, Elastomeric, Chemical Curing 

• CGSB 19-GP-14M Sealing Compound, One Component, Butyl-Polyisobutylene Polymer Base, 

Solvent Curing 

For non-structural applications, use acoustical sealants or adhesives specifically designed for 

polyethylene air barriers. 

7.3.8 Polyurethane sealant/Asphaltic materials 

Problem: Asphalt roofing materials contain solvents that can damage (poly)urethane sealants. The 

asphaltic materials contain solvents and plasticizers that dissolve and discolour urethane. The point 

of contact of asphalt materials with (poly)urethane sealants will result in discolouration of the 

sealant, eventual delamination of the sealant and, possibly, the softening and deterioration of one or 

both materials. 


Solution: When sealing to asphaltic roof membranes, use sealants and adhesives approved by the 

membrane manufacturer. 

32


Division 8–Doors and windows 

No reports 

Other door and window-related reports: 

Division 7–Thermal moisture protection 

• 7.1.3 Peel-and-stick membranes/Vinyl windows (page 24) 

33


Division 9–Finishes 

9.1 Coatings 


The use of paint, stain, varnish and other coating materials to provide colour and protection for 

surfaces is a broad subject. Numerous books, Web sites and articles deal with the subject. The 

durability of coatings is a combination of: 

• good surface preparation 

• good application techniques 

• selection of a coating with the best characteristics for the application. 

This section does not deal with all the ways coatings can fail, but will list some coating 

incompatibility problems particular to residential builders. Some specialty coatings may damage 

other coatings or materials. Therefore, it is important for the painter to ensure the product 

selected is appropriate for the application. The product label will give important information 

about application conditions, including surface preparation, temperature, curing times and times 

between recoats. Taking liberties with these directions could result in performance problems. 

It is important to note that paint will perform well only if it is applied at temperatures above the 

recommended minimum application temperature. In the rush to complete autumn projects, 

coatings are sometimes applied to substrates that are too cold for successful application and 

performance, including interior coatings applied before the building’s heating system is activated. 

Although water doesn’t freeze until the temperature drops to 0°C (32°F), it is not correct to assume 

that latex paints can be applied down to that temperature. In fact, the minimum temperature for 

latex paint to cure adequately is 10°C (50°F). 

Latex paints applied to surfaces below 10°C (50°F) will result in early failure of exterior coatings 

and poor washability for interior painted surfaces. Latex paint must be applied in the temperature 

range recommended by the manufacturers and for the curing time of the coating (usually two hours 

for latex paints and four hours for alkyd paints). In addition, paints specially formulated for low 

application temperatures can be used but these also have temperature limitations that must be 

respected. 

It is general practice in new construction for painting and related touch-ups and repairs to be 

completed just before the building is turned over to the owner. The colour of latex paint is affected 

by the temperature of the surface to which it has been applied. If painting is done in the spring or 

fall, when the temperature of the building interior is low, for example, 10 to 15°C (50 to 60°F) , 

and touch-ups are done at a higher temperature, the result will be two different colours from the 

same can. The best practice is to apply paint at or above the minimum recommended by the 

manufacturer. If these instructions are not followed, it is likely that touch-up paints will have to be 

colour-matched to wall colour. 

34


To maximize production, many painters use spray equipment to apply latex paints. The application 

may be spray alone, or spray followed by rolling to smooth and texture the surface. Because of the 

high pressures required to force the paint through the spray tip, colour changes take place during 

the application. Therefore, colour irregularity may occur between spray applications and subsequent 

touch-ups and repairs. Extra paint should be run through the spray gun and saved for touch-up and 

repair purposes. By doing this, any colour variation resulting from spray pressurization will apply 

equally to the application coat and subsequent touch-up. 

The application of alkyd (oil-based) paints at low temperatures–below 10°C (50°F) can cause loss 

of gloss if the coating is exposed to moisture (dew, fog, rain) during the curing process but they are 

less subject to damage when applied at low temperature than other coating products. When applied 

in low temperature, alkyd paint dries very slowly, but will eventually cure. When recoating in cold 

weather, longer dry times (48–72 hours) may be required to prevent wrinkling of the previous coat. 

The application of alkyd paints at temperatures below 10°C (50°F) may result in poor performance 

in the form of poor gloss. In addition, slower curing time means a longer period of exposure to 

damage from abrasion and wind-carried particulates. 

9.1.1 Paint/Wood knots 

Problem: Due to the high concentration of resins in wood knots, painting over knots will often 

result in discoloration of the paint. 

Dark-coloured paints applied to exterior wood surfaces with a southern or western exposure can 

result in the dark surface absorbing the summer heat, liquefying the resin in the knots, and causing 

the paint to wrinkle or peel. 

Reporting source: Paint industry expert 

Solution: Wood knots should be primed with a sealer prior to top coating with paint. Orange 

shellac is still a good material for priming knots or sap streaks in wood. Shellac loses its drying 

ability as it ages so use a test patch to ensure the shellac will dry. White shellac is not as effective 

and has a short shelf life. Proprietary primers that are shellac- (alcohol) based can also be used. 

Most of the varnishes sold today contain polyurethane, which is not compatible with shellac. When 

varnishing over sap or knots, apply the varnish directly to the wood and do not prime with shellac. 

35


9.2 Flooring, resilient 

General information: 

Resilient flooring is a popular flooring material that has a relatively firm surface but has “give” and 

“bounce back” when compressive forces are removed. Common types of resilient flooring include 

vinyl composition tile, vinyl tile and sheet, linoleum tile and sheet and rubber tile and sheet. 

9.2.1 Resilient flooring/Concrete sub-base 

Problem: Improper material selection can lead to premature failure of resilient flooring installed 

over concrete slabs: 

• Moisture emissions from the slab can lead to adhesive and flooring failure. 

• Concrete sealers and curing compounds may not be compatible with adhesives used to secure 

resilient flooring to the slab. 

• Adhesives: Some adhesives are not compatible with some types of resilient flooring and will 

cause shadowing or inadequate bonding. 


Solution: Follow instructions from the resilient flooring manufacturer carefully and carefully ensure 

that specifications for other areas of work (concrete slab placing and curing) are consistent with the 

warranty requirements for the floor covering. Failure to do so may result in premature failure and 

the voiding of warranties. 

• Moisture emissions from the slab: All concrete substrates must be fully cured and free of any 

hydrostatic and/or moisture problems. The moisture vapour emission from a concrete slab must 

not exceed 1.36 kg/92.9m 2 (3 lbs. per 1,000 sq. ft.) per 24 hours, as measured by test method 

ASTM F1869-98. 

• Concrete sealers and curing compounds: Concrete substrates must be clean and free of concrete 

sealers and curing compounds, and any substance that may prevent or reduce adhesion. 

• Adhesives: Resilient flooring manufacturers have tested their products with adhesives and 

provide strict directions on the compatible adhesives to use. Use only adhesives that are 

specifically designed, recommended and guaranteed by either the resilient flooring 

manufacturer and/or the adhesive manufacturer for the specified floor covering material. Check 

with the flooring and adhesive manufacturers for the latest product recommendations and 

warranty information. 

9.2.2 Resilient flooring/Wood panel sub-floor 

Problem: Certain wood panel underlays emit surfactants (surface-active contaminants) that can 

cause discoloration of resilient flooring. 


36


Solution: Verify with the resilient flooring manufacturer the types of wood panel sub-flooring that 

will be compatible with their warranties. Although building codes permit the use of several kinds of 

wood panel for sheathing and underlay, some resilient flooring manufacturers require wood 

underlay to be underlayment-grade with a fully sanded face. Such manufacturers do not usually 

accept particleboard, OSB, cement backerboards, glass mesh mortar units or acoustical cork. When 

specifying resilient flooring, check with the manufacturer for suitable underlayment so that 

warranties will be honoured. 

Most resilient flooring manufacturers recommend specific adhesives, seam sealers and floor care 

products that have been formulated and extensively tested for their products. In many cases, 

warranties will be voided if unapproved products are used. 

Specify wood underlayments recommended and guaranteed by either the wood underlayment 

manufacturer and/or the floor-covering manufacturer. All wood underlayments must be 

acclimatized and installed in strict accordance with the manufacturer’s written instructions. 

9.2.3 Resilient flooring/Floor fills and toppings 

Problem: Many products such as cellular concretes, resin-reinforced self-levelling cement 

underlayments and gypsum-based products are recommended by their manufacturers for use as 

floor fills or toppings. However, some resilient flooring manufacturers caution that 

“all recommendations and guarantees regarding the suitability of these products and their 

performance as underlayments (for resilient flooring) are the responsibility of the manufacturer 

and installer of the underlayment system used.” 

This warning is an indication that there have been performance problems when some types of 

resilient flooring have been placed over floors that have been levelled or topped. 


Solution: The manufacturers of resilient flooring, adhesives and cement-based self-levelling and 

patching products may not warranty their products when applied and installed over gypsum-based 

self levelling underlayment and gypsum-based patching compounds. Before completing 

specifications, consult with both the leveller/topping manufacturer and the resilient flooring 

manufacturer to ensure compatibility and the honouring of warranties. 

When self-levelling underlayments and patching products are required for the surface preparation 

of substrates prior to the installation of floor covering materials, specify cement-based products. 

9.2.4 Resilient flooring/Latex-backed rugs and mats 

Problem: It is reported that use of latex-backed rugs or mats over resilient flooring can cause 

discoloration of the resilient flooring. A typical example would be the use of a mat over the flooring 

in front of a kitchen sink. The latex backing may cause permanent discoloration of the resilient 

flooring. 

Reporting source: B.C. construction management company 

Solution: Before using any covering over resilient flooring, builders and homeowners should verify 

with the flooring manufacturer that the proposed mat and the resilient flooring are compatible. 

37


Division 10–Specialties 

No reports 

Division 11–Equipment 

No reports 

Division 12–Furnishings 

No reports 

Division 13–Special construction 

No reports 

Division 14–Conveying systems 

No reports 

38


Division 15–Mechanical 

Other mechanical-related reports: 

5.1.1 Copper tubing/Aggressive soils (page 19) 

5.1.2 Copper pipe/Plumbing (page 20) 

5.1.4 Metal strapping seismic restraint/Hot water heaters (page 21) 

7.3.2 Sealants/Vent pipes (page 29) 

15.1 High-temperature vent pipes/Combustion gas 

Problem: Failures have been reported in high-temperature plastic vent pipe (HTPV) and fittings 

that were installed between 1987 and 1993 for venting Class III mid-efficiency furnaces. The 

failures include hairline cracking, splitting, and separation of joints that can result in leakage of 

combustion products, including carbon monoxide, into the home. 

The deterioration of the pipe is thought to result from acids resulting from the combustion process. 

Horizontal pipe sections are at greater risk than vertical sections because condensate containing the 

acid remains in contact with the inner surfaces for longer periods. The damage is progressive, causes 

the pipes to become increasingly brittle and fragile, and it is not possible to predict when failure 

will occur. 


Solution: Vent pipes serving mid-efficiency furnaces installed between 1987 and 1993 should be 

inspected. Any defective pipe should be replaced. After 1993, the plastic pipe was reformulated to 

avoid the deterioration problem. 

39


Division 16–Electrical 

16.1.1 Smoke alarms/Halogen lighting 

Problem: There are reports that some types of hard-wired, multi-station smoke alarms commonly 

used in residential construction are prone to false alarms when they are wired in series with 

receptacles or fixtures that include halogen lighting. The false alarm problem can occur with multistation 

smoke alarms that are low-voltage interconnect units–when one smoke detector in a circuit 

goes into alarm, it sends a low-voltage signal (9VDC) to put the other alarms on the circuit into 

alarm. The false alarms are caused by voltage fluctuations resulting from the transformers powering 

the halogen lights. 

Nuisance false alarms can result in homeowners temporarily disconnecting the smoke alarm, or in 

some cases, removing the alarm, leaving no alarm protection in the case of fire. 

Reporting source: Construction management firm 

Solution: The best solution is to ensure smoke alarms do not share a circuit with other devices. 

Otherwise, check with the manufacturer to ensure smoke alarms are compatible with proposed 

wiring arrangements. This problem was reported for one particular type of smoke alarm. The 

solution reported is the use of another model (by the same manufacturer) that operates by 

maintaining a line voltage and is therefore less prone to voltage fluctuations in the circuit. 

16.1.2 Electrical wiring/CPVC pipe 

Problem: Certain types of wire and cable jacketing may contain “plasticizers” that are used to 

make the plastic insulation softer and more flexible. When wiring with jackets that contain these 

plasticizers are in constant contact with plastic components such as chlorinated polyvinyl chloride 

(CPVC) pipe, the plasticizers may leach out and cause the pipe to soften. Occasional contact 

during building construction (for example, dragging wires across CPVC pipe) does not seem 

to transfer enough plasticizer to cause a problem. 


Solution: Wiring should be kept isolated from CPVC pipe and other plastic materials. 

40


Trend Analysis 

The first effort at compiling examples of material incompatibility has generated 35 examples (in 

addition, there are many other examples that have not been included because they were seen to be 

inappropriate uses of materials or violation of well-known good practices). The analysis of the 

examples that were included in this report (and others that were not included) results in some 

general observations about particular areas of difficulty. 

Education 

Several examples were reported that involve dissimilar metals. While there will always be examples 

of incompatibility that cannot be avoided–even the manufacturer has not foreseen certain 

limitations–many incompatibilities are well documented but are either ignored or not recognized. 

Therefore, it is likely that recurring metal incompatibilities demonstrate a need for ongoing training 

or skills upgrading. 

Sealants 

Sealants are a group of materials with a fairly high number of reported incompatibilities. This is 

likely due to the wide range of formulations and applications for such products. Because they are 

often formulated for specific applications, problems or poor performance are bound to occur when 

a sealant is used for an application for which it was not designed.The General Information section 

for sealants will assist builder practitioners to make educated sealant selections. It would be helpful 

for all stakeholders if sealant tubes had a simple label used by all manufacturers that indicated 

product uses and limitations. 

Builder awareness 

Builder surveys provide insight into where the majority of building defects are occurring. 

A 1992 survey made by the NAHB Research Centre determined that the most frequent reports 

of callbacks were attributable to: 

• Paints/caulks/finishes 

• Flooring 

• Windows and skylights 

• Doors 

• Foundations and basements 

• Siding and trim 

• Structural sheathing 

• Wallboard 

• Foundation insulation and waterproofing 

• Framing 

41


A survey of the major housing defects reported to the Ontario Home Warranty Program in 1994 

by homeowners listed, in order of frequency, the following: 

• Gypsum wallboard 

• Foundation wall 

• Window/door/skylight 

• Trim and moldings 

• Windows/skylights/skylight frames 

Although there is no direct link between defects and incompatibilities, this information indicates 

assemblies that require special vigilance, and a reminder to ensure known building material 

incompatibilities are avoided as a possible source of failure in assemblies with a high history of 

defects. 

From time to time, new materials or building techniques enter the marketplace with the promise 

of performance and cost-effectiveness. In some cases, unforeseen service conditions or circumstances 

result in major difficulties. Exterior insulated finish systems (EIFS), composite sidings and 

polybutelyne water piping are examples of materials or systems that did not perform as expected, 

and indicate that product testing and building code development do not circumvent all possible 

problems. Therefore, the designer and builder need to continually be educating themselves and 

making careful choices based on experience and judgment. 

Builders are renowned for job-site ingenuity and innovation. Using tools and materials in 

unforeseen ways to ease effort may result in economies but may also result in unsafe work 

conditions or practices that violate building science principles or code requirements. Care is 

required when applying innovation, but as a minimum, job-site time savers should respect known 

material incompatibilities. 

Uses of materials 

In some cases, incompatibility results from using materials outside their range of approved or tested 

applications. For example, it was reported that contractor’s sheathing tape, designed for sealing 

vapour/air barriers, is used for applications for which it may perform but performance has not been 

tested or approved. 

The Canadian Construction Materials Centre (CCMC) is one of the organizations that evaluates 

new materials, products, systems and services for all types of construction. The results of the 

product evaluations are published in the highly regarded CCMC Registry of product evaluations. 

Published quarterly on the CCMC Web site (www.nrc.ca/ccmc/) and annually in print, the 

Registry contains evaluation reports that include complete, illustrated descriptions of products, 

instructions for use along with any restrictions and detailed test results. Each report also contains 

an impartial technical opinion of how a product performs in relation to its planned use. 

In the case of sheathing tape, the CCMC evaluations assess the performance of the tape with 

specific sheathing and membrane materials. If the tape is used with other sheathing material or for 

other applications, there is no guarantee of performance and in some cases, usage may be contrary 

42


to code requirements. For example, there are reports of both sheathing tape and duct tape being 

used to seal duct joints in forced-air heating systems without clear indication that the tapes meet 

the NBCC flame-spread requirements for such applications. 

Although duct tape has many useful temporary uses on the job site, its effectiveness for permanent 

applications is doubtful, and it is reported to have a very short performance effectiveness in 

applications close to heat sources. It is essential to ensure that innovative uses of products do 

not violate building code requirements. 

Instruction labels 

From the cases uncovered during the research for this project, it is obvious that some problems 

encountered by builders result from a failure to read or respect product limitations noted on the 

product packaging. For example, the rush to apply paint in unheated conditions as fall 

temperatures decrease often ignores the temperature application ranges recommended on the 

product. 

While exceeding the product limits may get the project completed in time, it also brings a fairly 

high likelihood of recalls later, often at higher cost than doing the work according to instructions 

in the first place. 

Trend summary 

Building is a complex process that requires knowledge of a wide array of products and principles. 

Education and continual skills upgrading is needed for building professionals to stay aware of the 

limitations of both old and new products. It appears that many incompatibilities could be avoided 

if: 

1. Manufacturers could find a clearer, harmonized way to indicate product limitations on 

product packaging. Sealants, for example, have numerous formulations and there are many 

manufacturers. A standard label on each tube of sealant indicating best uses, appropriate 

and inappropriate uses would help simplify product selection. 

2. Building professionals need to read and understand product uses and limitations and make 

product selections that will avoid incompatibility problems. 

43


Building Code Issues 

There were two reports that pertained to the building code and product standard. These have been 

passed to the appropriate agency for possible action. 

44


Appendix A: Research Sources 

This list summarizes the groups, publications, associations, companies and organizations contacted 

by telephone, e-mail or Web site review during the research stage of gathering cases of building 

material incompatibilities. 

Industry associations 

Alberta Floor Covering Association 

Alliance of Canadian Building Officials 

Building Envelope Research Consortium 

Building Owners and Managers Association 

Canadian Association of Home and Property Inspectors 

Canadian Home Builders’ Association 

Canada Mortgage and Housing Association 

Canadian Roofing Contractors Association 

Canadian Wood Council 

Construction Specifications Institute 

Energy & Environmental Building Association 

Forintek Canada Corp. 

Greater Vancouver Home Builders Association 

Homeowner Protection Office of British Columbia 

Manufactured Housing Institute 

National Association of Home Builders 

National Association of Home Builders Research, ToolBase Hotline 

Partnership for Advancing Technology in Housing (PATH) 

Starline Windows 

Architectural associations 

Alberta Association of Architects 

Architects’ Association of New Brunswick 

Architectural Institute of British Columbia 

Manitoba Association of Architects 

Nova Scotia Association of Architects 

Ontario Association of Architects 

Ordre des architectes du Québec 

Royal Architectural Institute of Canada 

Saskatchewan Association of Architects 

45


Government and regulatory bodies 

Canadian General Standards Board 

Housing and Urban Development (HUD) 

Institute for Research in Construction, 

Canadian Construction Materials Centre 

Occupational Safety and Health Administration 

Public Works and Government Services Canada, National Master Specifications 

Research and university 

Australian Material Safety 

Commonwealth Scientific and Industrial Research Organisation, Australia 

Concordia University, Department of Building, Civil, and Environmental Engineering 

Institute Of Materials, U.K. 

Oakridge National Laboratory, Energy Sciences 

Pennsylvania Housing Research Center 

University of Illinois, Seitz Materials Research Laboratory 

University of Maryland Materials Research Science and Engineering Center 

University of Ottawa, Environmental Health and Safety Service 

University of Pennsylvania, Materials Research Society 

University of New Brunswick, Civil Engineering, Materials 

University of New Orleans, Advanced Material Research Institute 

University of Southern Mississippi, School Of Engineering Technology 

University of Waterloo, Civil Engineering 

University of Windsor 

Publications 

ASM Handbook Volume 11: Failure Analysis and Prevention, R.J. Shipley, W.T. Becker, 

ASM International. 

Building Materials: Dangerous Properties of Products in Masterformat Divisions 7 and 9, H. Leslie 

Simmons, Richard J. Lewis, Sr., Wiley. 

Construction Sealants and Adhesives, 3rd Edition, Julien R. Panek, John Phillip Cook, Wiley. 

Durability by Design, National Association of Home Builders Research Centre, 2002. 

Failure Mechanisms in Building Construction, David H. Nicastro, American Society of Civil 

Engineers (ASCE Press), 1997. 

Wall Moisture Problems In Alberta Dwellings, Technical Series 2000-112, CMHC 

46


Periodicals 

AIA Architecture 

Architectural Digest 

Architectural Record 

Architectural Journal 

Architectural Record 

Builder Magazine (NAHB) 

Builder Online 

Canadian Building Digest 

Canadian Home Builder Magazine 

Canadian House and Cottages 

Fine Homebuilding 

Hanley-Wood Publications 

Homes and Cottages 

Journal of Light Construction 

McGraw Hill Construction (ENR, Sweets, Arch Record, etc) 

Progressive Architecture 

Professional Builder Professional Remodeler NAHB 

This Old House 

ToolBase E news 

47


Appendix B: Survey 

INCOMPATIBLE BUILDING MATERIALS 

In 2003, Canada Mortgage and Housing Corporation completed a report titled “Incompatible 

Building Materials” to document cases of building material incompatibility reported by builders, 

renovators, inspectors and architects. The report is intended to initiate shared learning so that 

others can avoid problems. 

The report is a start to the identification of building materials incompatibility. You can help by 

adding your knowledge and experience to future editions of the report by completing and returning 

the survey form below. 

Typical documented examples of incompatibilities 

Framing materials 

Fasteners affected by cedar, redwood and treated wood products in wet locations 

Wet materials: sealants, adhesives and coatings 

Solvent-based sealants, adhesives and damp-proofing affecting polystyrene rigid insulation 

Silicone sealant affecting paintability and recaulking 

General 

Metals affecting metals–dissimilar metals 

Copper tubing affected by aggressive (acidic soils) 

Your example 

Your name: __________________ Tel: ( ) ___________ Email: ____________________ 

Problem (symptoms, causes, conditions, time-frame etc.): _______________________________ 

____________________________________________________________________________ 

____________________________________________________________________________ 

____________________________________________________________________________ 

Solution (if there is one): ________________________________________________________ 

____________________________________________________________________________ 

____________________________________________________________________________ 

Return to: 

CMHC 

email: dsmith@cmhc.ca 

Policy and Research Division tel: (613) 748-2348 

700 Montreal Road, Ottawa, ON fax: (613) 748-2402 

K1A 0P7 

Att: Darrel R. Smith 

Senior Researcher 

48


Acknowledgements 

Canada Mortgage and Housing Corporation expresses its gratitude to the following organizations 

and individuals who contributed to this project. 

Advisory committee 

Walter Burningham, W.E. Burningham & Associates 

Don Johnston, Canadian Home Builders Association 

Alphonse Caouette, Canadian Construction Materials Centre (CCMC): 

Paul Morris and Jennifer O’Conner, Forintek Canada Corp. 

Bob Switzer, Polygon Construction Management Ltd. 

Skip Lennox, Glidden ICI Paints 

John Straube, University of Waterloo 

Chad Foreshew, Ontario New Home Warranty 

Rick Bortolussi, City of Richmond/B.C. Building Officials Association: 

Technical reviewers 

Lyndon Mitchell, NRC, “Division 3–Concrete” 

Sivan Parameswaran, NRC (retired), “Division 5–Metals” 

Paul Morris, Forintek Canada Corp., “6.1.1” 

Bruno Di Lenardo, Canadian Construction Materials Centre, IRC, “7.1 Envelope” 

Joseph Borsellino, Patenaude JBK, “7.2 Roofing” 

Jerome Klosowski, sealants expert, “7.3 Sealants” 

Skip Lennox, Glidden ICI Paints, “9.1 Coatings” 

Jean Claude Carisse, National Floor Covering Association, “9.2 Flooring, Resilient” 

Alberta Floor Covering Association, “9.2 Flooring, Resilient” 

Survey respondents 

Henry Bakker 

Kane Bentson 

Gilles Bernard 

Daryl Birtch 

Bart Blainey 

Rick Bortolussi 

Tom Bowen 

Eric Clough 

Gerry Coming 

Andy Cook 

Luis de Miguel 

Paul Denys 

Ted Gilmour 

Don Grant 

Jim Greenshields 

William Hadikin 

Wayne Heath 

Michael Hill 

Karl Klatt 

Ian Knight 

Walter Kuch 

Ben Levinson 

Richard Lind 

Dennis Looten 

Thorien Maillot 

Jack Mantyla 

Ted Maxwell 

Jim McCubbing 

Robert Mearns 

Bruce Miller 

Hugh Miller 

Jim Morrison 

Greg Nelson 

Myron Pasaluko 

Murray Pound 

Joe Ross 

Kevin Sawlor 

Andrew Skelton 

John Slowski 

Allen Smith 

Darrel Smith 

Bob Switzer 

Tom Trestain 

Bernardine Van der Meer 

Victor Zukowski 

Marshall Zwicker 

49

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23/06/05

Incompatible Building Materials - SCHL

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