I am working on replacing decking and found a couple of rotted joist I decided to replace as well.
The joist size is 2×8-12. I purchased the replacement joists however when I took one rotten out and compared with the new one, it turned out the new one is 1/4" wider. The label on both old and new joists says 2×8-12, but the exact width of the old one is 7" and new one is 7 1/4".
Did I get wrong product? The old deck may be 10 years old — is it just result of the wood shrinking over years? If so does it mean I can't replace a few joists and should do it for all of them?
Technically I could cut off the extra piece but if it is shrinking, then it will become uneven in a few years.
Any guidance would be much appreciated
Best Answer
It's hard to know how much of the 1/4" difference you're seeing is going to remain after the wood dries out. I'd take just a 1/8" notch out of the ends of the joists so they set 1/8" high in the joist hangers now, with confidence they will shrink at least 1/8" as they dry. If they shrink a lot and make a noticeable low spot, you can shim between the bottom of the hangers and the joists. (As long as you have access to the joists when the decking is on.)