Table 6-1.-Common Woods—ContinuedNominal, rough, green lumber has threeGradinggeneral classifications, according to size, asfollows:1. BOARDS—less than 2 in. thick and 1 ormore in. wide. If less than 6 in. wide, they maybe classified as strips.2. DIMENSION—at least 2 in. thick, but lessthan 5 in. thick, and 2 or more in. wide. It maybe classified as framing, joists, planks, rafters,studs, and small timbers.3. TIMBERS—smallest dimension is 5 ormore in. They may be classified as beams,stringers, posts, caps, sills, girders, and purlins.Lumber classified by extent of manufactureconsists of three types as follows:1. ROUGH LUMBER is not dressed (sur-faced) but sawed, edged, and trimmed to the ex-tent that saw marks show in the wood on the fourlongitudinal surfaces of each piece for its overalllength.2. DRESSED LUMBER is surfaced by aplaning machine to attain a smooth surface anduniform size.3. WORKED LUMBER is dressed and alsomatched, shiplapped, or patterned.According to the American Lumber Standardsset by the National Bureau of Standards for theU.S. Department of Commerce, lumber is gradedfor quality. The major grades of yard lumber, indescending order of quality, are SELECTLUMBER and COMMON LUMBER. Each ofthese grades is subdivided, also in descendingorder of quality.SELECT LUMBER has a good appearanceand good qualities for finishing. One kind of selectlumber is suitable for natural finishes; anotherkind, for painted finishes. Select lumber fornatural finishes is graded A or B. Grade A isnearly free of defects and blemishes, butGrade B contains a few minor blemishes. Selectlumber for painted finishes is Grade C or D. Theblemishes in Grade C are more numerous andsignificant than those in Grade B. Grade D haseven more blemishes than Grade C does. Eithergrade, C or D, presents a satisfactory appearancewhen painted.COMMON LUMBER is suitable for generalconstruction and utility purposes. It, also, issubdivided by grade in descending order ofquality. No. 1 common is sound, tight-knottedstock, containing only a few minor defects. Itmust be suitable for use as watertight lumber.6-6
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