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Allowing for Shrinkage when Sawing Framing Lumber
Question
Forum Responses
From contributor D: Watch out for wind shake in those hemmies. I run into a fair amount of it here in PA, and am therefore inclined to cut it for use for non-structural needs, such as b&b siding, and the like. From contributor A: When it comes to grading... You will pick better grade lumber for your own projects than you can buy at the store. I can't believe they put a stamp on a 2x12 with a knot so big and loose, it is really a 2x8 after you figure deflection. I've rough cut pine and poplar 1/8" over for 2x4's and 3/16" for 6's. More for 10's and 12's, with no planing. This was a workshop. If you want to use sheetrock and want nice smooth interior walls, you might want to plane them. Also, wood moves with wood. Wood moves, rock will crack. From contributor P: If you saw to a full 2", you will need to frame with 20p nails instead of the typical 16p nails. I saw all my rough cut framing lumber to 1-3/4" o.c. with a bandsaw for the final thickness after drying (and minus the kerf) is about 1-5/8". For width, I saw green lumber to these widths:
If you saw to these dimensions, all your dried lumber should exceed the minimums that Gene quoted.
From contributor R: I've cut a bunch of West Virginia hemlock and if you cut it 1 1/2 x 5 1/2, it will shrink about 1/16'' on the 1 1/2'' and about an 1/8'' or less on the 5 1/2. From contributor B: I built my kiln out of rough cut wood - I cut everything to 8/4 slabs and dried. Then I put back on the mill and edged one side. Then I put about 4 slabs on at a time with the straightlined edge down and measured up from the bottom to get the correct starting cut to end up with all 3 1/2" wide boards, figuring the kerf as waste and measuring on the widest slab. (Use 5 1/2" for your 2x6's and so on.) For most of your construction, the thickness of the board does not matter, just the width. For those that were critical, I planed. The result was that my studs ended up being about 1 7/8"x 3 1/2" with the defects being largely removed by my edging all boards after they were dry. The extra thickness only makes the boards a bit stronger.  Click here for higher quality, full size image From contributor R: I cut this hemlock on the Turner mill at 6/4 on the scale, and after a few years here is what it scales out today. No, I didn't cut that on the 6/4 - I cut that at 5/1/2'' on the scale.  Click here for higher quality, full size image Here is what they dry out to at 6/4 after a few years.  Click here for higher quality, full size image From Professor Gene Wengert, forum technical advisor: The amount of drying depends on the final MC. In a garage or other unheated structure including a shed, the lumber will be around 12% MC. In a house wall during the heating season, the wood can be closer to 8% MC. In this drier climate, the wood will be 1% smaller. That is 1/16" in width. The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment). Comment from contributor F:
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