Many proud new homeowners in the U.S. may be about to lose the roof over their heads -- literally. A fire-resistant plywood widely used in the roofs of nearly 1 million town houses during the past decade has turned out to have an unexpected vulnerability. Over just a few years, the heat of the sun triggers a chemical reaction that causes the wood to blacken, decay and eventually collapse. Result: a sudden epidemic of leaky buildings, expensive repairs and bitter lawsuits.
Makers and suppliers of FRT (fire retardant-treated) plywood, which was used mostly in houses east of the Mississippi, insist that...