Floor OSB's final f

LTOW THAT OSB reportedly comI \ mands a 757o share of the North American residential structural panel market, the last significant residential sub-market left for it is in flooring.

An engineered wood panel made from strands of small-diameter trees aligned longitudinally and laterally in alternate layers for structural strength, OSB has more or less taken over residential wall sheathing and roof decking. Its share in structural panel flooring, however, is about one-third, with plywood accounting for the balance.

The introduction of premium OSB ber or laminated veneer lumber. If these systems are installed correctly, one manufacturer guarantees them for the life of the building. but more companies are developing water resistant, large warranty OSB floor panel products." floor panels bonded with advanced resins. and half a dozen competing manufacturers planning to develop similar panels, is paving the way for OSB to eventually capture the residential flooring market, according to the Structural Board Association.

Another manufacturer guarantees its special OSB flooring panels, used for residential and commercial single-layer and sub-floor applications, for 50 years. Manufacturers are also selling thicker OSB structural panels made for sturdier sub-floors. Heavier panels bounce less when walked on.

These value-added elements, from thicker to higher-resin water resistant OSB panels, are being marketed the most in single-layer floor construction.

A number of companies already offer such panels as a packaged flooring system, which include I-joists that are made up of a thin OSB web bonded to top and bottom flanges of lum-

OSB's key product advantage is based on performance standards matching those of plywood and lower manufacturing costs. The high quality OSB floor panels on the market now match prices of non-OSB panels but are being purchased for their higher value-added content.

Even in the Northwest, where moisture is a key concern and builders tend to have a stronger preference for lumber, a fair amount of OSB has been sold for single-layer flooring, according to Darin Thompson, OSB, lab and composites division manager of Tsco, a certification firm. "Plywood still dominates but more companies are developing water resistant, large warranty OSB floor panel products."

A project manager from Eugene, Or., says, "We have lumberyards where the quality of OSB is enhanced while that of plywood is decreasing so that the quality differences for flooring are becoming difficult to distinguish."

OSB's performance standards are no different from plywood. Panels, however, must be covered on the construction site, lest they be exposed to rain. "OSB can be substituted, thickness for thickness, for plywood essentially in equivalent structural applications," says Professor Jim Bowyer of the University of Minnesota's Department of Wood & Paper Science.