H2 Treatment
Preservative treatment level for interior framing protected from weather, designed to resist termite and borer attack in dry, above-ground conditions.
Hazard Class 2 under AS/NZS 1604.1 covers timber used in interior, above-ground, fully protected applications such as wall studs, plates, and roof trusses. The treatment guards against termites and borers but is not designed for prolonged moisture exposure. H2 chemistry can be either water-borne (often shown as 'H2 blue' in southern states) or LOSP-based, with chemical loadings specified in AS/NZS 1604. The treatment is mandatory in many termite-prone areas under the BCA's Volume 2 and AS 3660. Buyers should note that H2-treated timber must not be used externally or in contact with concrete slabs in wet conditions; specify H3 or H4 for those applications instead. Always check the end-tag for hazard class and treatment chemistry.
Values and references on this page are indicative and drawn from common industry sources. Always verify the current AS/NZS standard, manufacturer data sheet or NIAA policy publication before relying on figures for design, specification or compliance work.
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