Center Cut Lumber And Warping Wood Stair Treads
One of the biggest
problems with wood and even metal sometimes is that it isn't completely
stable. In other words, depending upon where the wood was cut out of the
log (tree) and how it was fastened and what it was fastened to and
believe it or not, what it was fastened with could make all the
difference in the world.
It isn't uncommon to see a tread, warp or twist, over a short period of time. Wood stair treads usually warp if the lumber wasn't dried properly or stored correctly. One time I purchased an 8 foot 2 x 12, which I was going to use for a stair building video and within two weeks, it warped.
Now here's the secret, if you notice the 2 x 6 stair treads in the picture above, the one in front or the one on the left is warped more than the one on the right. That's because it was cut from the center of the tree. The farther you get away from the center of the tree, the more stable the wood will be, most of the time.
You could actually eliminate some of your warped stair tread problems, by selecting the correct lumber. Try to avoid using lumber that has any part of the center of the tree running through it.
Here is a side view picture of a cut log showing the center of a wood tree.
You can clearly see this 2 x 4 was cut from the center of the tree. The round dot near the center of the 2 x 4 was actually the center of the tree.
This is probably the worst spot you can cut lumber from for any home building project, including stairs. You need to find lumber that isn't cut from the center or near the center like of the picture below. I don't know all of the scientific reasons why lumber from the center or near the center of a tree tends to warp and twist more than lumber from the outer areas, but it does and it shouldn't be used for stair treads.
Lumber that's away from the center has a tendency to remain straighter and might require the stair builder to pay premium prices for it. Don't forget there are different grades of lumber and you should familiarize yourself with them, before designing and building your stairway.
Here is a side view of two 2 x 6 construction standard pieces of lumber that weren't cut from the center of the tree and therefore might not warp or twist. Remember, there's no guarantee that lumber like this won't warp or twist, but at least it will reduce the chances of it happening and that's all we're looking for.