Levels of Treatment – Hazard Class Guide

Wood preservative treatment level is specified using the same hazard level scale used to indicate hazard level:

HAZARD CLASS EXPOSURE SPECIFIC SERVICE CONDITIONS BIOLOGICAL HAZARD TYPICAL USES TREATMENT OPTIONS AVAILABLE AT FISHER’S
H1 Inside, above ground Completely protected from the weather and well ventilated and protected from termites Lyctid Borer Framing, flooring, furniture, interior joinery Not available
H2 Inside, above ground Protected from wetting, Nil leaching Borers and termites Framing, flooring, structural materials, plywood flooring, lintel, bearers, joists and beams, used in dry situations H2 Tru-Core Red
H3 Outside, above ground Subject to periodic moderate wetting and leaching Moderate decay, borers and termites LVL/Plywood (glue-line treatment), decking, posts, framing, hand rails, subfloor timbers, joists, fascia, window componentry, weatherboards, cladding, pergolas, veranda, door frames and sills H3 Tru-Core Green
H3 Tru-Core Clear
H4 Outside,
in-ground contact
Subject to severe wetting and leaching Severe decay, borers and termites Highway noise attenuation walls (plywood), subfloor timbers, fence posts, greenhouses, pergola posts (in-ground) and landscaping timbers H4 Tru-Core Brown
H5 Outside, in-ground contact, contact with or in fresh water Subject to extreme wetting and leaching and/or where the critical use requires a higher degree of protection Very severe decay, borers and termites Retaining walls, piling, house stumps, building poles, cooling tower fill Not available
H6 Marine waters Subject to prolonged immersion in sea water Marine wood borers and decay Boat hulls, marine piles, jetty cross bracing Not available
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