To the Editor: I read your article "Fire-Retardant Trusses at Risk" (Eight-Penny News, 2/94) with great interest — because the "next wave" the article referred to has arrived. My firm was recently contacted by a commercial building owner to investigate the catastrophic collapse of the roof on a 10-year-old, 12,000-square-foot, two-story office building in Laredo, Texas. The collapse occurred during business hours and could have had disastrous consequences but for an alert employee who looked into the attic space to investigate the noises they had been hearing. He noted some split trusses, and got the building evacuated moments prior to the collapse. Our investigation resulted in an opinion to the owner that the treated trusses had failed structurally and the failure was