I learned long ago that when installing exterior wood decks that the boards should be laid with the heart of the tree facing up to minimize cupping. I’ve always done it this way with good success. A friend just mentioned to me that he’s had several jobs where the deck boards cupped, and when I asked him what orientation he used, he said heart of the tree down. I suspect that’s his problem, but I’ve long since forgotton WHY my way makes sense.
So … do others agree with my way, and can anyone explain it? I’m sure I read it in FWB but I’m a charter subscriber and don’t feel like going through all those back issues … it just makes me feel old!
Thanks, Bill.
Replies
tangential shrinkage.
Follow the curve of the grain in coss setion and see that the curves nearest the heart cover less distance on the space of a board than those of newer growth.
Since shrinkage is a factor of a percentage of the distance covered in each grwoth ring,there is more shrinkage in the outer growth rings than in the wood loser to heart
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I like to think of it as the growth rings want to flatten out.
No matter what you do you'll get some cupping though, particularly with decks in the sun.
Half the time, you pick out the best face of the board. You don't always have the choice of either side. You can usually spot individual boards that are prone to cupping, not all will do so regardless of which face is up. Typically, the board will cup away from the center of the tree. If you want the belly up, to shed water, the heart goes up. More of an issue with wider boards that aren't securely fastened.
Beat it to fit / Paint it to match