1) For 4" thick material that is 8" or greater in width, the F_b value may be multiplied by 1.1

2) For sizes wider than 12", use 90% of the F_b, F_t, and Fc// specified for the 12" width. Use 100% of the F_v, F_c^ (perpendicular-to-grain), and MOE specified for the 12" width.

3) In construction where three or more load-carrying members such as joists, rafters, studs or decking are contiguous or are spaced not more than 24 inches in frame construction and are joined by transverse floor, roof or other load distributing elements, an increase in bending stress of 15 percent for members used in such systems is allowed as a design consideration, as provided in ASTM D1990.

4) For flatwise use, the following adjustments apply to the Fb values. These adjustments are not applicable to the values listed in Table 5.

Nominal thickness		2" & 3"	4"
Width	4"	1.10	1.00
	5"	1.10	1.05
	6"	1.15	1.05
	8"	1.15	1.05
	10" & wider	1.20	1.10

5) All stress rated grades under these rules are established on a basis that permits cutting graded members to shorter lengths without impairment of stress ratings in the shorter pieces.

6) See paragraphs 163-164.4 for conditions applicable to seasoned lumber.In widths of 12" and less in lengths of 24' and less, seasoning is required for all lumber of 2" thickness and less, but has to be specified if desired for other widths and lengths or for thicknesses in excess of 2".

7) Grade restrictions established under the SPIB Standard Grading Rules apply the entire length of each piece, and each piece therefore is suitable for use in continuous spans, over double spans or under concentrated loads without the necessity of regrading for special shear or other special stress requirements.

8) The allowable unit stresses for all stress rated grades under these rules are for normal loading conditions and apply in all cases other than those for which special exceptions are to be made. Where a member is to be fully loaded to the maximum design stress for many years, either continuously or cumulatively, working stresses 90% of those indicated herein should be used.The stresses may be modified on a similar basis for railroad bridges and other structures that involve unusually hazardous or severe service conditions.

9) Compression perpendicular-to-grain values are design stresses for 0.04" deformation.For design stress at 0.02" deformation, use 74% of the corresponding tabulated values.

10) The allowable unit stresses and adjustments apply to lumber used under conditions continuously dry, as in most covered structures.

11) Lumber 2-1/2" ® 4" nominal thickness above 19% (S-GRN) and lumber in service under wet conditions of use or where the moisture content is at or above the fiber saturation point, as when continuously submerged, the recommended design values shall be multiplied by the following factors: All stress rated grades under these rules are established on a basis that permits cutting graded members to shorter lengths without impairment of stress ratings in the shorter pieces.

Property	Factor
Fb <= 1150 psi	1.0
Fb > 1150 psi	0.85
Ft	1.0
Fv	0.93
	0.67
Fc// <= 750 psi	1.0
Fc// > 750 psi	0.8
MOE	0.9

12) Lumber chemically treated may require adjustments to the recommended design values.Reference should be made to the American Wood Preservers' Association Standards and the National Design Specification of the American Forest & Paper Association.