Historical: Fire Retardant Treated/PT Lumber - 2015
This information reflects our best understanding of product composition in 2015.
To become fire retardant, lumber is soaked in a treatment bath of water and additives, under pressure, until the bath solution has permeated the structure of the wood. The bath is drained and the wood is dried to a 19% maximum humidity level,...
More about Historical: Fire Retardant Treated/PT Lumber - 2015
To become fire retardant, lumber is soaked in a treatment bath of water and additives, under pressure, until the bath solution has permeated the structure of the wood. The bath is drained and the wood is dried to a 19% maximum humidity level, leaving the additives behind in the cells of the wood. Fire retardant lumber (FRT) is rated for either interior applications (UFCA rated by the American Wood Protection Association) or exterior applications (UFCB). This CP describes UFCA FRT, intended for various uses – joists, partitions, etc – where the lumber will not be exposed to moisture or outdoor conditions.
A more up to date Common Product is available here: Fire Retardant Lumber.