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.

Relative Humidity, Part I

Some time back, we had a customer make an inquiry to the effects of very low humidity coupled with extreme variances in temperature. I told Charles I would look into the thing, and possibly come up with a few conclusions about the topic. It turns out the effects of humidity and temperature variation on organic building supplies is a little more complicated than I’d initially thought, especially considering the wide variances among different wood species.

Kansans and Muscovites can look forward to this in about six months.


Further complicating a relatively simple inquiry is the fact that climactic variations throughout North America are extremely large. Virtually every condition in which man resides can be found somewhere in the United States. A blanket explanation or a simple chart is therefore impractical when considering the specific climactic occurrences one could encounter throughout the country.

The best thing a homeowner, contractor, or design specialist can do to ensure the maximum utility of their wood decking and siding products is to properly acclimate the wood to its new environment. I’ve written a little about this before. It is occasionally difficult for the contractor to exercise patience at this point of the process, as most of our orders are of a very time-sensitive nature. Skipping this important step in the process will only degrade the quality of the finish installation.

The science behind the nature of wood acclimation over time still fascinates me, however. It is impossible to predict exactly how any particular species will perform on site without first knowing the moisture content of the species at the point of installation, the length of time the acclimation process occurs on site, and the relative humidity and temperature variations of the installation climate. I’ll begin with some fundamental knowledge here, which is required for any further scientific explanation of this common and accepted variation in organic building supplies.

Simply put, relative humidity takes into account the pressure, temperature, and amount of water vapor present in the air to determine a uniform, temperature-neutral measure of the current air makeup. Relative humidity provides a little better measure of what’s actually going on as it relates to current weather conditions. I don’t know how much stock to put into the explanation found here, as I am not a scientist. I’m pretty sure that atoms bounce around at different rates depending on how warm they are. I leave further explanation of the phenomenon to the experts.

What’s important to the contractor and end-user is the net effect on the finished product. Checking is pretty common in dense timbers such as Ipe, where moisture within the timbers attempts to equalize with the moisture norms of its new environment over time. I don’t have a whole lot to say about other climates around North America. My experience in one of the most extreme climates in the world tells me that if it’s good enough for Kansas City, it’s probably going to be good enough for your location as well, so long as a few precautions are taken to value the overall appearance of the installation.

After doing some very basic research with the almanac, about the only other place on earth I can find with such a similarly severe continental steppe climate is that of Moscow. So, I’ll make the broad brushstroke here that woods such as Ipe, Cumaru, and Massaranduba would very likely take the pounding just about anywhere. No other places where people substantially congregate on earth experience the oppressive humidity, extreme hot and cold, and subsequent dryness associated with harsh winter with the steppe climate seen in Kansas City and Moscow. Five or six days a year, however, it is quite nice here. Probably most urban Russians could make a similar claim. Today is not one of those days. It is very likely to reach 105 degrees Fahrenheit here today with something meteorologists call a heat index in the neighborhood of 120 degrees. That means it’s pretty damned humid. So, if I’m still alive tomorrow, I’ll follow up on section II of this series. We’ll explore in greater detail just what to do about phenomenon such as today.

Minnesota: Closed for Government

I wish I could explain Minnesota politics, but I cannot. There is a hell of a history in the land of 10,000 lakes. Professional wrestlers, comedians, and representatives with quite aggressive foster parenting histories adorn the history of politic in the state.

Well, they’ve outdone themselves and shut down their operations, but at least they hired someone to make a sign explaining the government shutdown, purportedly with government dollars. Will the Feds be next? I hadn’t heard of a debt deal yet today..

An article in this week’s Economist covers the Minnesota debacle much more clearly than I can.