Until recently, Canada's Icynene (800/758-7325) was the only company in North America offering low-density spray foam insulation to home builders. Now, however, a second company, Quebec-based Demilec (514/437-0123), has introduced a very similar product at a competitive price. Demilec, Canada's largest producer of high-density spray polyurethane insulation, is promoting its new low-density foam, Sealection, through an established network of commercial high-densityfoam contractors. Demilec executive Dave Lall says commercial highdensity- foam contractors asked the company to develop a less expensive product they could sell to residential builders. " The residential market is ten times the size of the commercial market," says Lall. "We haven't even seen the tip of the iceberg yet." Generic foam? Several U.S. urethane suppliers are also poised to enter the arena with their own versions of the water-blown foam. Although officials could