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A OFTWOOD LUMBER Per9 formance should never be a problem if alldealers and consumers are scrupulous in buying only material carrying an American Lumber Standards Committee approved grading mark.

Since Sept. I, 1970, Product Standard 20-70, commonly known as PS 20-70, has ensured the quality of some 770 billion board feet of U.S. produced lumber. That's enough lumber to rebuild every housing unit now standing in the U.S. and then some, according to Tom Searles, executive vice President of the ALSC.

Written by the ALSC as a National Grade Rule for dimension lumber, PS 20-70 ended a maze of softwood grading rules, working stresses and span tables stemming from traditional regional practices and preferences based on species and growing regions.

Forging a common national standard took nearly a decade, but the result provided uniform nomenclature and a standard Product description for dimension lumber regardless of the species or region of manufacture.

The standard set an industry Precedent by defining dry lumber as that with a moisture content of l9olo or less. It also set different minimum dressed sizes for green and dry lumber to compensate for shrinkage of the unseasoned lumber.

actively pursuing the do-it-yourselfer.

Although structural panels have been considered environmentally sound since they often use second growth logs, underutilized species and recovered fiber to some extent, preservationists are creating problems for the industry. Log shortages have closed five plywood mills in the northwest. Southern states, too, face pressure as preservationists extend their area of concern to private timberlands. Obtaining the raw materials necessary to manufacture the structural panels necessary to meet the demands they have created is the industry's biggest challenge at present.