Treated Plywood

Treated plywood provides added durability for a range of applications.

Overview

Protecting plywood
Plywood may be subject to decay and/or termite attack under certain conditions. In-ground applications can cause both decay conditions and termite attack. Correct preservative treatment against fungal attack, or rot, is essential for all plywood, either painted or unpainted, that is to be permanently exposed to the weather.

Infestation with termites is usually not a problem for plywood when used in above ground applications.

When should plywood be treated?
Plywood can either be treated by impregnation of veneers, prior to manufacture or by pressure treating manufactured plywood. Pressure treating plywood is an 'envelope treatment' only, treating the outer veneers, edges and ends of sheet. The preservative may not penetrate through the glue lines to the middle veneers. If plywood is cut, then localised paint on preservative treatment is required to the cut edge. This treatment is only practical for thicker panels.

It is important to note that preservative treating after manufacture or surface treating with 'brush on' preservatives should be done only after machining, sawing and boring has been completed. Some preservation treated plywood will be difficult to bond, particularly if phenolic or resorcinol adhesives have been used.

Preservative treated plywood is suitable for painting provided manufacturers recommendations are followed.

Plywood treatments
A range of preservative treatments are available for plywood including CCA (copper chrome arsenate), LOSPs (light organic solvent preservatives) and for veneers, Ruply and ACQ (Alkaline Copper Quaternary Compounds).

For building construction, the most suitable treatments are CCA and LOSP.

Plywood with a Type A bond used as exterior cladding must be treated against fungal and insect attack. This should be with a minimum of hazard level H3 for 'outdoors above ground' as per AS/NZS 1604.3.

Most softwood species can be treated with non-leachable preservative salts, which will impart decay resistance. The level of preservative treatment specified for softwood laminated beams used in Service Class 3 applications should be H3. Similarly LOSP envelope treatment can be used satisfactorily. It is always best to check with the manufacturer for recommended use.

Ongoing maintenance and inspections will help to make sure rot/infestation does not occur in structural above-ground applications.

Learn more
You can find out more detailed information about plywood here.

Properties


*Disclaimer : The species mentioned here are just a guide and for specific information refer to Suppliers Section

Description

Applications

  • Exterior Stairs

    For outdoor applications, timber is one of the leading material choices. Timber use in external staircase applications creates structures of strength and durability, sheathed in a natural beauty that blends seamlessly with the outdoor environment.

  • External Cladding

    The natural appeal, versatility and strength of timber makes it the superior choice for external cladding. Through specification, planning, design and finishing processes, timber cladding not only creates a building of superior strength, acoustic and thermal performance but also creates a place of beauty, style and natural appeal.

  • Framing

    Since people began building simple shelters, wooden framing has played an important role in shaping structures of many kinds. One of the most popular types of wooden framing is known as lightweight timber construction.

  • Shear walls

    Lateral loads such as wind or earthquake on framed timber buildings - either post and beam or stud and joist - need to be resisted and shear walls and diaphragms offer an effective and economical solution.

  • Timber Joinery Products

    Timber joinery products offer a classic, unique and stylish touch to any interior design.

  • Timber Portal Frames

    For buildings that require large spans and column free interiors, timber portal frames provide one of the most aesthetically pleasing solutions. Utilising modern engineering technology, portal frame design transforms timber into a highly effective, efficient and economical structural product. This application guide provides a comprehensive overview of the process of using timber in the specification, fabrication and erection of portal frame structures.

Case Studies

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