New grading rules are announced

\ffESTERN Wood Products Assn., W which supervises quality control for 4A/o oI the nation's output of softwood lumber, will publish and distribute ne\d grading rules about July lst.

' Building materials dealers WVPA-stamped lumber easier to merchandise under the new rules, pror.riises the world's largest sawmilling organization, because builders and architects will find western lumber more efficient to use.

Among the improvements are these: i (8) The same grade in all species will have a uniform appearance, with respect to knots, slope of grain and other visual grade limitations.

(1) Sizes of 2" Iraming lumber and boards will relate to moisture content, requiring unseasoned lumber to be cut large enough to allow for subsequent shrinkage. Nominal 2" lumber dried to I9/o mois, tu*e content will be surfaced u1 ll/r". Uns€asoned lumber will be surfaced to l-9/16". Widths are also related.

(2) Span tables will be more accurate, since lumber design values are based on the newest standards developed by the American Society for Testing and Materials. ASTM employed the latest refinements in technical data derived from the Wood Density Survey made by the U.S. Forest Products Laboratory, and from other research findings of recent years.

;(3) Numbers will replace names for dimension grades, except for the top grade. Desigtrations will be Structural, #\ #2, #3 and $4.

(4) Working stresses will be adjusted to reflect the new data. Modulus of elasticity (MOE) is assigned downward by grade, and tension values are reduced.

(5) Stress grading will extend to all Structural, SI and $2 dimension lumber 6" or more in width, to Structural grade in 4/' width, and to 2x4s in the Light Industrial Framing category.

(6) Applicable working stresses will be shown for the first time for all II western species covered by WWPA's quality control program.

' 1Z; F,rll length grading will apply to all stress grades of 2" lumber, allowing tlre user to cross-cut a long piece and still letain the same stress capability in the shortened piece.

(9) Western species listings are re. duced by a new combination to be stamped "Hem-Fir." Covered by the HemFir stamp will be western hemlock, several true firs, and that Douglas fir which grows in Arizona, Colorado, Nevada, New Mexico and Utah.

Story oI q Glonce

New grading rules from WWPA will be published next month. Here is a first look at them, how they've changed and how they remain the same. Changes should make western lumber more efficient for builders and architects to use.

(I0) Rules for board grades have been so simplified they will occupy only eight pages, compaied to more than 60 in the outgoing 1965 Grading Rules book. The grade levels remain unchanged.

(11) A streamlined system to select the right pieces for particular joist and rafter spans has been created to eliminate time-consuming calculations and reduce L2 DRY tWro J Y.7 J.E R.F errors. Mills ailopting this system will include on the stamp for each piece J and R symbols. and these will key to a simple span chart. which WWPA will supply without charge.

Western Wood Products Assn. states that its new grading rules are the first in the lumber industry to embrace the latest technical findings of ASTM. This assures more efficient and aecurate use of the western species. And about tl billion board feet of production annually is graded under WWPA supervision.

These are the first rules that relate sizes of 2" nominal lumber to moisture content, recogarizing the shrinkage lactor as wood dries out. They relate unseasoned sizes to dry, so that lumber manufactured to both conditioru will reach comparable size in use.

,The changeover from the old grading rules, which have been in force since 1965, will proceed during the year, and a final deadline for its completion in all mills may be fixed by the association's direc. tors sometime this autumn. The date will depend in part on consumption of existing stocks at the mills and in distributing and retail yards, it was stated.

Production oI l1/2" dimension has been growing steadily, along witl rising usage.

Promotion Kit Available

WWPA is promoting its lumber chang. es intensively, to acquaint builders and designers, as well as dealers, with their meaning and benefits. A merchandising kit is being ofiered to dealers, containing bannerso mailer pieces, and three information items: a revised Product Use Manual, a new Grade Stamp Manual and a Grade Change Guide.

t32sB @'u, 15 @ DRY

Irstud

L2

16,50f

@TOP SInilP (of three) illustrates WWPA's new shortcut for determining joist and rafter spans. Letter symbols at lower edge key to simplified span table. In all stamps, mill number will appear over regist'ered trademark at left, atd grade ef pieca in big type at center. Species is at lower right, in this case the new Hem-Fir grouping. DRY at upper right indicates lumber was not over 19% moisture content when manufactured. Center stamp shows top studs grade, with Lodgepole Pine the species, atd condition of dryness at not more than 15% moisture content when manufactured. Bottom stamp: Light Industrial and Heary Industrial Framing grades will be identified by appropriate "f" fiber stress-in-bending value. This is of great use in truss rafter construction. Stanp shown curies highest 'if" Jatiq in new Hem. Fir species group.

Any dealer may obtain his kit, plus quantities of any of its selling aids, without charge by writing to Western Wood Products Assn., Rules 68-P, 700 Yeon Bldg., Portland, Ore. 97204. Charge for the 1968 Grading Rules Book itself is $1.

Lumber graded under the revised rules being published in July by the Western Wood Products Assn. can be specified and used with greater assurance that its capabilities will match the intended use, WWPA's officials emphasize.

Lumber finished at a maximum of. l5/o m.c. may be stamped 'oMC 15." Unseasoned need not be so marked, but if it has been cut smaller than the related sizes requireo it must carry its size and ooUNSD,'o standing for unseasoned, on the stamp.

All stress grades of 2" lumber will be graded the same for the full length of the piece.

Beams and stringers and 3" and. 4" thick dimension sizes will continue to be graded more restrictively in the middle one-third, as they are generally used in the full lenEth ordered.