Fire Retardant Lumber
This information reflects our best understanding of product composition in 2022.
Untreated lumber is soaked in a pressurized vacuum-sealed treatment bath of water and additives, until the fire retardant (FR) solution has permeated the structure of the wood. The bath is drained and the wood is dried to a maximum moisture...
Untreated lumber is soaked in a pressurized vacuum-sealed treatment bath of water and additives, until the fire retardant (FR) solution has permeated the structure of the wood. The bath is drained and the wood is dried to a maximum moisture content level of 19% (15% max for plywood), leaving only the FR 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 was scoped for interior above-ground structure use where fire retardant treated wood (FRTW) acts to delay the spread of fire and degradation of the structure.
A historical version of this CP is available here: Historical: Fire Retardant Treated/PT Lumber - 2015.