Q. We have always used pine for our doors, but recently had a request to use ipe. We were impressed with the color and so on, but we seem to be having moisture issues such as buckling, etc. Any hints?
A. Let’s compare pine and ipe briefly. Pine (I’ll use eastern white pine as an example) when dry weighs about 20 pounds per cubic foot, has a compression strength of 440 psi across the grain, has a surface hardness of 380 pounds, changes size about 1 percent radially (across the rings when viewed on the end grain) with a 14 percent MC change and changes size 1 percent tangentially (parallel to the rings) with a 5 percent MC change.
Ipe weighs about 55 pounds per cubic foot, has a compression strength of about 1200 psi, hardness of 3,680 pounds, changes size about 1 percent radially with a 9 percent MC change, sand changes size 1 percent tangentially with a 5 percent MC change.
Both are similar in size change when the humidity changes, which will result in a MC change. However, ipe is quite a bit stronger, with the compression strength being at least three times more than pine and the hardness nearly 10 times.
Stated another way. When the size changes with pine, especially compression, the pine can much more easily absorb the stress by compressing slightly than can ipe. So, you are able to miss the in-use MC target and have in-use MC changes with pine that will create excessive stress and possibly pop nails, buckle and so on.
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