Laverne Dalgleish - Basic Air Barrier Requirements

All About Air Barriers – 

The Basics 

ABAA XX-XX Rev 0 issued March 2013

ABAA Process for Approval 

– Explained 

Air Barrier Association of America (ABAA) is a Registered Provider with 

the American Institute of Architects Continuing Education Systems. 

Credit earned on completion of this program will be reported to CES 

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members are available on request. 

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construed to be an approval or endorsement by the AIA of any material 

of construction or any method or manner of handling, using, 

distributing, or dealing in any material or product. Questions 

related to specific materials, methods, and services will be 

addressed at the conclusion of this presentation.

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© Air Barrier Association 2013

Air Barrier Association of America 

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communication represents an official ABAA technical viewpoint, shall: 

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• This is an AIA Accredited Presentation 

• This presentation will not highlight focus or reference to a specific product of 

manufacturer

Learning Objectives 

• Explain “air barrier” terminology 

• Understanding building science principles 

• Explain air barrier basics 

• List air barrier codes and standards 

requirements

• air barrier material 

Definitions 

building material with an air permeance not greater than 0.02 

L/s·m² at 75 Pa that is designed and constructed to provide 

the primary resistance to airflow through an air barrier 

assembly. 

• Vapor Permeable (vapor Barrier) 

The property of having a moisture vapor permeance rating of 

10 perms (5.7x 10 -10 kg/Pa◦s◦m 2 ) - IBC [5 perms (2.9x 10 -10 

kg/Pa◦s◦m 2 ) – IRC] or greater, when tested in accordance 

with the desiccant method using Procedure A of ASTM E96.

• air barrier accessory 

Definitions 

materials designated to maintain air tightness between air 

barrier materials, air barrier assemblies and air barrier 

components, to fasten them to the structure of the building, 

or both. 

• air barrier assembly 

combination of air barrier materials and air barrier 

accessories that are designated and designed within the 

environmental separator to act as a continuous barrier to the 

movement of air with an air leakage not greater than 0.20 

L/s·m² at 75 Pa.

• air barrier system 

Definitions 

combination of air barrier assemblies and air barrier 

components, connected by air barrier accessories, that are 

designed to provide a continuous barrier to the movement of 

air through an environmental separator . 

• air barrier components 

pre-manufactured elements such as windows, doors and 

service elements.

Definitions 

• Water vapor permeability 

time rate of water vapor transmission through a material at a 

specific thickness. This would be most applicable to materials 

that can vary in thickness such as boardstock, fluid-applied, spray 

polyurethane foam (SPF) air barriers. 

• Water vapor permeance 

the time rate of water vapor transmission through a material of a 

unit thickness. Permeance is a performance evaluation and not 

a property of a material. This would be most applicable to 

materials which don’t vary in thickness such as self-adhered 

sheet materials and mechanically fastened building wraps.

Six Air Barrier Materials 

• Mechanically Fastened - Membranes 

• Mechanically Fastened - Insulating Boardstock 

• Mechanically Fastened - Non-insulating 

Boardstock 

• Self-adhered Membrane 

• Fluid-applied Foaming 

• Fluid-applied Non-foaming

Building Science 

The definition of building science is the 

“ 

physics of: 

• Heat flow 

• Air flow 

• Moisture flow – in a building


The building is a system. 

A building is made up of many components 

that work together: 

• Building enclosure 

• People 

• Mechanical system 

• Ambient conditions


The building enclosure is: 

• The building components that separate 

one environment from another 

environment. 

• Includes inside environment from 

outside environment 

• Can also include one environment from 

another environment within a building


People effect buildings by: 

• Daily activities (bathing, breathing, 

cooking, etc.) 

• How they treat the building envelope 

(opening window, etc.) 

• How they operate the mechanical 

system (positive or negative 

pressurization)


Mechanical systems effect buildings by: 

• Adding / removing heat 

• Adding / removing moisture 

• Creating different air pressures 

• Moves air / heat / moisture from one part of 

the building / building component of another


Ambient conditions effect buildings by: 

• Air leakage containing water vapor 

• Bulk water leaking into walls through: 

• voids in WRB 

• improper drainage in design/installation 

• Creating different air pressures 

• Drying potential of climate 

• Freeze/thaw


Effects of uncontrolled air leakage…


Heat always flows from hot to cold 

Heat Flow: 

• Requires temperature difference 

• Rate is dependant on temperature 

difference 

• Greater temperature difference equals 

greater heat flow


What are the three ways heat flow? 

• Conduction 

• Convection 

• Radiation


Conduction: 

• Heat transferring through 

a substance 

• Rate is based on 

temperature difference 

• Different materials have 

different flow rates 

What are examples of heat flow by 

conduction?


Convection: 

• Heat transferred from one surface 

to another surface by means of a 

fluid medium (ie. air, water, etc.) 

• Rate is based on temperature 

difference and type of medium 

What are examples of heat flow 

by convection?


Radiation 

• Heat transferring from the 

source to an object without 

heating the medium 

between 

• Rate based on strength of 

heat source and ability of 

object to absorb energy 

What are examples of heat flow by 

radiation?


Pressure differences are caused by: 

• Stack effect 

• Wind effect 

• Flue and ventilation effect


Stack Effect 

• In winter warm air rises and causes: 

• Exfiltration (positive pressure) at top 

• Infiltration (negative pressure) at bottom 

• In summer the air pressures are opposite: 

• Exfiltration (negative pressure) at top 

• Infiltration (positive pressure) at bottom

STACK EFFECT 

Building Science


Wind Effect 

• Wind blows against the building and 

causes: 

• High pressure on the windward side 

• Low pressure on leeward side 

• Infiltration on windward side 

• Exfiltration on leeward side 

• Low pressure forces can be higher than higher 

pressures

WIND PRESSURE 

+ PRESSURE 


- PRESSURE


Mechanical pressurization and ventilation 

effect: 

• Fans draw air through a building 

• Will create negative and positive pressures in 

a building 

• Causes infiltration and exfiltration through a 

building

MECHANICAL 

PRESSURIZATION 

Building Science

MECHANICAL 

PRESSURIZATION 

Building Science


Moisture (water): 

• Can exist as a solid or liquid 

• Moves from wet to dry 

• Moves to the path of least resistance


Water moisture flows four different ways: 

• Gravity 

• Capillary 

• Diffusion 

• Air transport

Gravity 


Use shingles, flashings, etc. to protect buildings 

It has been estimated that bulk Water causes 90% of the 

problems in buildings.

Capillary 


Use a capillary break or moisture barrier to protect building


Diffusion - through a material 

Use a vapor barrier / vapor retarder to protect building

Air Transport 


Use an Air Barrier or do air sealing to protect the building


1 METRE 

1 METRE 

TRANSPORT VIA AIR LEAKAGE 

30 LITRES 

2 cm x 2 cm HOLE 

TRANSPORT VIA DIFFUSION 

0.5 LITRES 

*ASSUMES RH 40%, 2 COATS ENAMEL PAINT, OTTAWA CLIMATE


Water vapor condensing in the building 

envelope leads to problems 

such as: 

• Mold 

• Corrosion 

• Wood rot 

• Ice lensing, etc.


Relative Humidity 

• The amount of moisture in the air compared 

to the amount of moisture the air can hold at 

a specific temperature. This will change as 

temperature changes even when the absolute 

humidity remains exactly the same.


Dew Point 

• The temperature where the relative 

humidity reaches 100% and the water vapor 

changes to liquid water 

• Remember liquid water causes 90% of the 

problems in buildings


Conclusion 

• Need to look at buildings as a system 

• Air barriers are only one component, we 

need to look at insulation, drainage, 

permeability, ambient conditions, etc 

• You need to address mechanical systems 

with building air-tightness 

• Building enclosures are important link to 

building performance and energy efficiency

Introduction to Air Barriers 

What materials does ASHRAE 90.1 classify as 

air barrier materials? 

• Plywood-minimum 3/8 in. 

• Oriented strand board-minimum 3/8 in. 

• Extruded polystyrene insulation board-minimum ½ in 

• Foil-faced urethane insulation board-minimum ½ in 

• Exterior gypsum sheathing or interior gypsum boardminimum 

1/2 in. 

• Cement board-minimum 1/2 in. 

• Built up roofing membrane 

• Modified bituminous roof membrane


What materials does ASHRAE 90.1 classify as 

air barrier materials? 

• Fully adhered single-ply roof membrane 

• A Portland cement/sand parge, stucco, or gypsum plasterminimum 

1/2 in. thick 

• Cast-in-place and precast concrete. 

• Sheet metal 

• Closed cell 2 lb/ft 3 nominal density spray polyurethane foamminimum 

1 in.


What materials are NOT classified as air 

barrier materials? 

• Tempered hardboard, plain fiberboard, flakewood board 

• Asphalt saturated felt paper (15# and 30#) 

• Vermiculite insulation 

• Concrete Masonry Units 

• Expanded Polystyrene 

• Glass fiber rigid insulation board 

• Asphalt-impregnated fiberboard 

• Glasswool & Cellulose Insulation 

• Brick


Air barrier materials can be: 

• Vapor Permeable (high perm rating) 

• Non-Vapor Permeable (low perm rating - 

provides vapor barrier function) 

• Insulation (providing air, vapor and thermal 

function)


Air barrier assembly key requirements 

• Continuity (most important / most difficult) 

• Strength 

• Durability 

• (Im)Permeability


Air barrier system requirements 

• The air barrier system shall be joined in an air-tight and 

flexible manner allowing for the relative movement of 

elements due to structural and hygrothermal 

expansion/contraction. 

• Connections using transitions shall be made between: 

• foundation and walls 

• walls and windows or doors (different wall systems) 

• penetrations 

• roof and wall 

• change in plane 

• change in substrate


More than just air permeance? 

• ABAA has developed listed of other physical properties and 

performance requirements for a variety of commercially 

available air barrier materials. This is based on four key 

requirements which attempt to duplicate loads on the 

building: 

• Air leakage 

• Continuity 

• Strength 

• Durability

Liquid Applied Membranes

Self-Adhered Sheet Air Barriers

Medium Density S.P.F.

Mechanically Fastened Building Wraps

Boardstock Air Barrier

Code Requirements 

• ASHRAE 90.1-2010 

• ASHRAE 189.1-2011 

• 2012 IECC (International Energy Conservation 

Code) 

• 2012 IRC (International Residential Code) 

• 2012 IgCC (International Green Construction 

Code) 

• 2012 IBC (International Building Code) 

• State code changes

ASHRAE 90.1-2010 

Code Requirements


ASHRAE 189.1-2011


2012 IECC – Commercial Buildings


2012 IECC – Residential Houses

2012 IRC 


2012 IgCC 



2012 IBC 

• There are no air barrier requirements in the 

2012 International Building Code.



Check the ABAA website for up to date 

information regarding code and standards 

status, and further links regarding code 

information in various states.

It is proposed that LEED v4 will reference ASHRAE 90.1-2010 

as the baseline standard for energy efficiency in LEED 

buildings. 

What does this mean? 

LEED Requirements 

LEED buildings will require air barriers as a 

mandatory component.

States that currently require air barriers by 

code: 

• Illinois 

• Massachusetts 

• Minnesota 

• Georgia 

• Rhode Island 

• New York 

• Maryland 


Code Requirements – Whole 

Building Air Leakage Testing 

Washington State: buildings over five stories 

require a whole building test but the code 

does not require the building to pass a 

prescribed value. 

City of Seattle : All Buildings require a whole 

building test conducted but the code 

requirement does not require the building to 

pass a prescribed value.

• Peanut butter 

Air Barrier Material??? 

– Smooth peanut butter 

– Applied at 20 mils wet 

– Tested to ASTM E2178 

– Air leakage result - 

0.0021 L/s·m 2 

– Is an air barrier material but cannot be installed as 

a continuous one and will not stand up to servicelife 

conditions.

Learning Objectives 

• Explain “air barrier” terminology 

• Understanding building science principles 

• Explain air barrier basics 

• List US air barrier codes and standards 

requirements

Thank you for your time! 

QUESTIONS?? 

This concludes The American Institute of Architects Continuing 

Education Systems Program 

1600 Boston-Providence Hwy 

Walpole, MA 02081 USA 

www.airbarrier.org

Contact 

Laverne Dalgleish 

ABAA – Executive Director 

ldalgleish@airbarrier.org 

1-866-956-5888

Laverne Dalgleish - Basic Air Barrier Requirements

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