Fire retardant plywood
Also: FR plywood, fire-retardant treated plywood, FRT plywood
Plywood treated with fire retardant chemicals (typically nitrogen and phosphorus salts) that reduce its rate of flame spread, smoke production and heat release. Achieves Euroclass B-s1,d0 or better under EN 13501-1.
Fire retardant plywood is conventional plywood (birch, beech, pine or mixed hardwood) processed with fire retardant chemistry to delay ignition, slow flame spread and reduce smoke release. Treatment is typically applied by full vacuum-pressure impregnation (chemicals penetrate every veneer of the panel) or by surface impregnation (outer veneers only). The treated panel is graded under the European Reaction-to-fire system EN 13501-1; Paged FR products generally achieve B-s1,d0 - the strictest practical class for combustible materials in construction.
FR treatment retains the structural and aesthetic properties of plywood, so panels can be machined, glued, painted or finished with veneers. Where moisture exposure is expected, multi-layer protection systems such as DryGuard FR combine fire retardant compounds with hydrophobic coatings to prevent leaching of the salts.