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Sizes
The WoodWorks Sizer database includes timbers up to 16 x 16 in. (406 x 406mm) in size; however availability of large sizes should be checked before specifying. Timbers may be obtained in lengths up to 30 ft. (9.1m), but this should also be confirmed with local suppliers. Actual sizes for design as compared with nominal sizes are given in NDS Table 1A, using dry sizes for design in all conditions.
Species and Grades
Sizer includes all species and grades listed in the NDS Supplement. D.Fir-L, Hem-Fir, S-P-F and Southern Pine are the species groups most readily available in timber sizes. These "major" species are in a separate material selection called Timber-soft; less common selections are in Timber--other and hardwood in Timber-hard.
The most readily available grades are No. 1 and No. 2; however, Select Structural may be ordered. Materials available from lumber yard stock are usually re-sawn to order from large timbers and should be re-graded after cutting. Verification of the grade may be obtained in writing from the supplier, or a qualified grading agency may be retained to check the supplied material.
Checking
Timbers are always dressed green since their large size makes kiln-drying impractical. As a result, some amount of shrinkage and checking can be expected after dressing. These effects are taken into account in the specified strengths.