Warps: Causes and Solutions

We had a customer inquiry today about warping, and I thought I would place some response here. This article by Eugene Wengert and Dan Meyer from the University of Wisconsin is the most succinct summary of the prevention and remediation of warp I’ve been able to locate.

My response to the customer follows:

I'd like some clarification about your product. You say the decking has warping. An unusable warp represents significant deflection across both the x- and y-axes looking at a crosscut of endgrain. (product has a twist to entire length of stock)

Crooks, which I think are what you might be referring to here, are deflection across just the long presentation axis (where clips are inserted) of your surface boards. A bow would be remedied simply by installing the boards, I would think. I've never seen cupping be a serious issue with our stock.

Ipe is as solid as any organic building material you'll find, fire rated the same as steel or concrete. But with any organic product there are bound to be some imperfections from time to time. The sawyer won't always get it just right at the mill, so when the stock dries there is always the possibility of an issue. What is the volume of product that is twisted and unusable from your order? If you could take some pictures of these boards, that would be very useful to us.

I just finished replacing a fire escape with treated lumber, and I wouldn't use that stuff on anything that was my own. The owner selected that product due to monetary constraints, and within four or five years it is going to show. That contemporary treated product simply hasn't been given an acid test against midwestern weather yet, in my opinion. Yellawood, and other products like it, are going to be a decent selection for anyone who doesn't mind redecking every decade or so...or who doesn't mind annual maintenance of the product.

There was plenty of bowing of that material (and even a bit of bowed/crooked warping--I think I returned a couple of deck boards out of about 25...) We recommend to our customers to account for 8% waste in placing their order, so that the worst of the stock can simply be set aside for use in smaller cut runs. Bowing/crooking of any material longer than 8' is fairly common, and at 1" over 14', I would think most of the stock of that nature could be used. It's not always handy, but I've never built a deck that was particularly fun. Then again, I'm getting too old to be fooling around on many more decks.

Please give me a ring if you would like to further discuss this issue. Bugs won't be a problem with that species. The oils and genetic makeup of Ipe naturally provide all the protection against decay a person would need against the elements. Rot should occur under only the most exceptional of circumstances, and would require a little bit of creativity and bad planning to accelerate the process. The wood, once installed, is rock solid.

We at Specialty Lumber Solutions encourage our customers to order about 8% of waste above their order for a couple of reasons: 1) Every twelve deck boards or so, the worst board (usually still very high quality) is set aside for shorts and fill ins down the road; and 2) It’s a small buffer for minor underestimations of the takeoff. I’m guilty of this myself. On my last project, I was sent to the lumberyard after my initial delivery because of the unexpected and due to my own error. That 8% won’t always get your back, but it would have saved mine in this instance.

I’ve had pretty good luck getting rid of moderate crook with a couple of guys armed with chisels. It’s not particularly fun, but it is effective.