HOW DURABLE IS FIRERETARDANTTREATED PLYWOOD? This is the first house in Florida built of fire-retardant-treated wood. It's Type-A rating from Underwriters Laboratories qualifies it for use in high-humidity environments. by Steve Carlson A handful of roof failures spawns a storm of controversy Do the chemicals used to make plywood fire resistant also make it brittle and punky? Reports of roof failures involving fireretardant- treated (FRT) plywood are being examined by groups within both industry and government. But don't expect any firm conclusions for at least a couple of years. Producers of FRT plywood readily agree that treatment inherently causes a slight structural weakening of the wood, which should be taken into account in a building's design. That's not a bad tradeoff, they say,