Building elements may be exposed to a range of physical, chemical or biological hazards which vary with the end-use application.
Hazards to wood include:
These are described in more detail in Hazards - Printable PDF.
Preservative standards specify the levels of protection against the potential threat of the most important biological hazards to timber in any particular end-use application, Hazard Classes.
This is achieved through the impregnation of a chemical treatment to eliminate or minimise any future in-service susceptibility to these hazards.
NB: The code has changed as of April 2011 to use H1.2 for Timber Treatment for enclosed framing. Read the brochure Pink is Tough - H1.2 Frames it Right here.
All other website information is being updated gradually.