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Is T2 treated timber standard?

It's increasingly standard in many volume builder contracts, particularly in Queensland. However, it is not always included in base prices — confirm with your builder.

What is the difference between T2 and H2 treated timber?

T2 is a treatment level under one classification standard, while H2 is a hazard class under a different (but related) standard. Both describe treated timber suitable for in-ground and above-ground applications respectively. Your builder should confirm which treatment their frames use.

Does T2 treatment replace termite barriers?

No. T2 timber treatment reduces the risk of termite attack on the frame itself but is not a substitute for a full termite management system. A chemical or physical termite barrier should still be installed.

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Home›Build Knowledge Hub›Building Process›Frame & Structure›Timber Treatment Ratings Explained

Frame & Structure

Timber Treatment Ratings Explained

A complete guide to Australian timber treatment hazard classes — T1 through T5, what they protect against, and which level your home needs.

5 min·Compare My Build — Independent Resource· Updated June 2025

Introduction

Australian Standard AS 1604 classifies treated timber by hazard class — H1 through H6 (or equivalently T1 through T5). The classification indicates the environment in which the timber will be used and the threats it needs to resist. Knowing which class is appropriate for each application in your home helps you evaluate builder inclusions more accurately.

Complete Treatment Ratings Guide

Hazard Class (H/T)	Application	Protects Against	Typical Use
H1 / T1	Interior, above ground, dry	Lyctid borer	Indoor furniture, interior framing (low risk)
H2 / T2	Interior, above ground	Borers + termites	Wall frames, roof trusses (standard new homes)
H3 / T3	Above ground, exposed to weather	Borers, termites, moderate decay	Exterior cladding, pergolas, verandahs
H4 / T4	In ground, not in water	Full protection, high decay	Fence posts, in-ground structural members
H5 / T5	In ground, wet conditions	Full protection, severe decay	Marine pilings, permanently wet applications

Common Builder Inclusions

›H2/T2 is the standard for internal wall and roof framing in residential new builds
›H3 treatment is required for exposed outdoor timber (pergolas, decks, fascia boards)
›Most builder inclusions specify H2/T2 for frames — H3 for outdoor structural elements
›Always ask your builder to specify the treatment level in your contract