guide to the specification, installation and use of preservative treated ...

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GUIDE TO THE SPECIFICATION, INSTALLATION
AND USE OF PRESERVATIVE TREATED
ENGINEERED WOOD PRODUCTS
PREFACE
This guide is intended to operate as an industry application document in conjunction with the suite of
relevant Australian Standards and the Building Code of Australia (BCA).
The scope of this document is limited to the specification, installation and use of both untreated and
preservative treated, glued EWPs, specifically including glued-laminated timber, laminated veneer
lumber (LVL), plywood, oriented-strand board (OSB), particleboard and I-beams.
This document is intended to provide a user-friendly and informative guide for the best practice
selection, preservative treatment, design, installation and finishing of EWPs to ensure product fitness
for purpose and performance over a range of applications, hazard exposures, and design lives. The
target users would primarily be designers, builders, engineers, specifiers and other users of EWPs.
In the broad sense EWP’s may be taken to include a wide range of glued or mechanically joined (nailplated)
products. In the context of this publication, Engineered Wood Products (EWPs) are defined
as structural timber composites formed from various timber or wood components in combination with
adhesives. Nail-plated beams and trusses, and medium density fibreboard are considered outside
the scope of this document. Other products such as parallel strand lumber and laminated strand
lumber are not generally available in Australia and are also not within the scope of this document.
There has been a significant increase in the product range, applications and volume of Engineered
Wood Products (EWPs) used in the construction industry over recent years. EWPs, including
Laminated Veneer Lumber (LVL), plywood, glued-laminated timber (Glulam), strand and wood residue
based products, are used in a variety of exposure hazards where treatment and or finishing systems
should be used to adequately protect the product and ensure its performance over its intended life.
Coupled with this is an increasing focus on the durability performance of buildings as evidenced by
the ABCB publication “Durability in Building Guideline 2006”. There is a need to ensure the correct
specification and application of EWPs matched to an understanding of product performance over the
design life. Availability of appropriate documentation would greatly assist in addressing the commonly
held misconception that EWPs can be substituted for solid timber products.
As far as authorship, Harry Greaves has written the sections covering treatment specifications and
hazard classifications and Stephen Bolden has prepared the balance.
The authors wish to thank the following organisations for their contributions in the form of
photographs:
Timber Queensland Ltd
Hyne & Son Pty Limited
Carter Holt Harvey Wood Products Australia
Doug Mayes (Builder)
Egger
Tilling Timber
Assistance of the following people is gratefully acknowledged in the preparation of this document:
Colin Mackenzie of Timber Queensland Limited for his thoughts, comments, photographs and
other constructive input
Simon Dorries of Engineered Wood Products Association of Australasia for his review,
comments and other constructive input
Kevin Lyngcoln of Lyngco Consulting for his review, comments and other constructive input
Sarah Postan (Holmes McLeod) for literature searches and preparation of some tables.
Jesse Riley (Holmes McLeod) for preparation of some of the diagrams.
Many others who have assisted in the provision of information and in the editing and review of
the various drafts.