Association Rules for Structural Timbers

ASSOCIATION RULES FOR STRUCTURAL TIMBERS Yellow Pine The rules or specifications for structural timbers adopted by the Yellow Pine Manufacturers Association are: No. 1 Common Timbers Sizes. Common Timber shall be worked to the following: 4x4, 4x6, 6x6, %-inch off side and edge. Surfaced 4 sides, 3/4-inch off each side; 6x8 and larger, S-3-S or S-4-S, 3/4-inch off each side surfaced.

Rough Timbers, 4x4 and larger, shall not be more

than 3/4-inch scant at any point when green, and be well manufactured, with not less than three square edges, and will admit sound knots that do not occupy more than onethird the cross-section of the piece or small defective knots.

Timbers 10x10 in size may have a 2-inch wane on one corner, measured on faces, or its equivalent on two or more corners one-third the length of the piece. Larger sizes may have proportionately greater defects.

Shakes extending not over one-eighth of the length of the piece are admissible, and seasoning checks shall not be considered a defect.

Dressed Timbers shall conform in grading to the specifications applying to rough timbers of same size.

Rough Timbers, if thicker than specified thickness for dry or green stock, may be dressed to such standard thickness, and when so dressed shall be considered as rough stock.

West Coast Timber The grades for structural timbers adopted by the West Coast Lumber Manufacturers Association (applying chiefly to Douglas fir) are as follows: Clears—Shall be sound lumber well sawed, one side and two edges free from knots and other defects impairing its use for the probable purpose intended. Will allow in dimensions larger than 6 by 10 inches pitch pockets when not extending through the piece; lightcolored sap on corners not exceeding 3 inches on -face and edge, knots 2 inches and less in diameter, according to size of piece, when on one face and one-half of each corresponding edge, leaving one face and upper half of each edge clear.

Select.

Shall be sound, strong lumber, well sawed. Will allow in sizes over 6 by 6 inch, knots, not to exceed 2 inches in diameter, varying according to the size of the piece; sap on corner not to exceed 2 inches on both face and edge; pitch pockets not to exceed 6 inches in length. Defects in all cases to be considered in connec

tion with the size of the piece and its general quality.

Merchantabl.

This grade shall consist of sound, strong lumber, free from shakes, large, loose, or rotten knots, and defects that materially impair its strength, well manufactured, and suitable for good, substantial constructional purposes. Will allow slight variations in sawing, sound knots, pitch pockets, and sap on corners, one-third the width and one-half the thickness, or its equivalent. Defects in all cases to be considered in connection with the size of the piece and its general quality. In timber 10 by 10 inches and over, sap shall not be considered a defect. Discolorations through exposure to elements, other than black sap, shall not be deemed a defect excluding lumber from this grade if otherwise conforming to merchantable grade.

Common—This grade shall consist of lumber having knots, sap, and other defects which exclude it from grading as merchantable, but of a quality suitable for rough kinds of work.

American Society for Testing Materials The American Society for Testing Materials has been working for many years to establish commercial standards for all structural materials upon a scientific basis. The specifications which it has adopted for structural timber are as follows : I. Definition of Structural Timber By the term "Structural Timber" the Committee understands all such products of wood in which the strength of the timber is the controlling element in their selection and use. The following is a list of products which are recommended for consideration as structural timbers: Trestle Timbers—Stringers, caps, posts, mud sills, bracing, bridge ties, guard rails.

Car Timber.

Car framing, including upper framing; car sills.