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Where in the World Was Craig?
By Craig DeWitt


Last week's post contained some weather data for Dubai in the United Arab Emirates, home to the world's tallest building, the Burj Khalifa. This building contains about one million square feet (100,000 square meters) of hardwood flooring. That's a lot of potential issues, especially with their outside conditions. The building is complete now, but while it was being built, they did encounter some flooring issues. Some were due to climate control issues. From what I saw on this trip, they have things pretty well under control.

As a comparison of climates, a dew point of 55 F degrees gives you about 50% RH at 75 degrees. So you can vent with that all day, and just add or remove a little heat to maintain 75 degrees. When you get to a dew point of 75 degrees, you have to remove half the water in the air to get to a RH of 50%. We have to do that in the Southeast, and sometimes the Midwest, in the summer. And we often struggle to do it. Places like Tucson have a lower dew point, and may be hotter outside. You would have to add water to get to 50% RH and 75 degrees indoors.

But at a dew point of 86, like they have in Dubai, you have to remove twice as much water as we do in the Southeast U.S. to get to 50% RH at 75 degrees. That's hard to do with standard A/C equipment. And equipment failures can result in wild humidity swings in a hurry. I covered some of this in my Wood Floors and Summer Moisture webinar. I'll cover more in an upcoming Winter Moisture webinar.

Dubai was probably the cleanest city I have been in. The architecture was beautiful. Getting around was easy and inexpensive, but you could spend a lot of money there if you wanted to. The indoor ski slope was pretty neat. And if you think the Mall of America is big, you should see the Mall of the Emirates.
Can You Guess Where This Is?
By Craig DeWitt

Well, Johannes, ya didn't even give people time to think about my last post showing some teak on the deck of a boat with some caulking between the boards. The flooring (or decking) was left unfinished, and in some spots not sanded very well or with torn grain. And on this boat, you spend the whole time barefooted, so some of us got a few splinters. The caulk appears to have been trimmed flush with a razor blade, which would have been a lot of knee time.  Has anyone done this system in a residential setting?

Here's a different scenario for you that I observed that same week: Outside dew points vary from 54 degrees F to 84 F within a week's time. (That's nicely dry air to sopping wet air. For comparison, Miami's dew point ranged from 62 F to 78 F this summer.) During this same week, outside temperatures ranged from 84 F to 107 F, and relative humidity levels ranged from 84% to 17%. Now you need to install floors that can survive this ventilation air. (And you must have ventilation air.) To maintain 35-55% RH indoors, you could use an air conditioner, swamp cooler, dehumidifier and/or humidifier, and some good controls to run the appropriate equipment, essentially depending on which way the wind is blowing. Can you guess where this is?
Carolina(s) On My Mind
By Howard Brickman

I hope that my loyal fans will forgive the temporary lapse in blogging. Hurricane Irene blew through town, taking with her our electricity for almost a week. On the plus side, I got to break out my “Survivorman” skills and lived to tell the tale. Wood has many other uses besides wood flooring. With my handy new Rocket Stove I was able to cut up the fallen branches and heat water for coffee and tea and also cook some one-pot meals.

By the time my power was restored, I was off to Charleston, S.C., to attend a wood floor class organized by Selva Lee Tucker featuring faculty from North Carolina State University. I must say: The class was yet another home run by Lee. With 10 years of instigating wood floor technical training under his belt, Lee has a knack for seamlessly combining hard-core practical and scientific knowledge.

The four-day class was instructed by two North Carolina State wood science professors and a wood floor guy from the Boston area. (Guess who the latter was?) The fee was $495, and those in the know can appreciate what an incredible value that is. It was a sell-out crowd, with over 50 attendees flying in from all over the U.S.

This was the sixth collaboration between Lee and NC State Wood Science faculty, several of which I have attended. Two of NC State’s finest taught fundamentals regarding the effects of moisture on the building envelope. An all-encompassing body of information was presented regarding the effect of temperature on relative humidity, how moisture moves through building components, and how fungi develop when exposed to moisture.

Dr. Phil Mitchell, wood products extension specialist and associate professor, has extensive experience working at major universities (Mississippi State, North Carolina State), and international wood products manufacturers (Weyerhaeuser). Dr. Phil is an acknowledged authority on the wood-moisture relationship with regard to academic as well as practical applications.

Dr. David C. Tilotta, associate professor and housing extension specialist, has a great deal of experience with contamination of buildings from chemicals and water, with extensive research and teaching background at the University of North Dakota and North Carolina State University. Dr. Dave introduced a software program from Oak Ridge National Laboratories that models temperature and moisture movement in exterior wall, floor, and roof systems.

On a personal note, do you remember how intimidated you were by your professors in college? This couldn’t have been further from the case with these two fun-guys who taught about fungi (pun intended). Tilotta and Mitchell are two of the best-natured and engaging college professors, and they took some fairly complex material and made the concepts much easier to digest (another fungi pun). The presentations were excellent, and the ease with which they answered questions worked to support true understanding. I left wishing that they had been my professors when I was an undergraduate (back when dinosaurs roamed the earth).

It has been exciting to see a major university put some effort into supporting the wood floor industry. Those of you out there who need studies, research, or laboratory testing should have the folks at the NC State Wood Products Extension Department on speed-dial. Dr. Phil’s email is

Last year, I had the opportunity to attend a three-day Wood I.D. class at the NC State Wood Anatomy Lab led by two of the leading wood anatomists in North America. The class was my personal favorite, and I’m hoping that it will become an annual event or at least every other year. I could see myself making a pilgrimage to attend. Even after 33 years in the wood flooring industry, I’m always pleasantly surprised to take away new insights about my specialty.

Stay tuned for my next blog: a step-by-step checklist to minimize installer liability when there are problems on the job.
Water & Wood: The Ultimate Test
By Craig DeWitt

Here's a photo I took of a wood floor last week:

Boat floor.jpg

Does anyone want to venture a guess as to what the black stuff is between the boards?  I'll give you a hint: The floor is on the deck of a boat.

It looks like a nice way of detailing the floor that will handle water well. But from what I can tell, the floor is only about 8 months old. I'd love to see it again in a couple years. And I don't think it would work on a floor where finish would be applied. I don't even know if this floor can be oiled.

Covered areas of the boat’s floor are parquet glued to plywood and finished with a glossy top coat. Here's a cross section view of a hatch cover in the floor:

Boat wood floor interior.jpg

We've put water all over this floor for days, with no apparent effect. Again, the floor is only 8 months old or so, and it would be interesting to see how it holds up to salt and fresh water over time.

A Lightning Strike & a Sloped Floor
By Craig DeWitt

This inspection didn't involve a hardwood floor, but it could have. It did have what I would call a "pre-existing condition."

The homeowner had been away from her 30-year-old house for a couple weeks. When she came home, she noticed some cracks in the ceiling and walls of her house, and a slope to her living room floor. The neighbors indicated that lightning had hit a tree between their houses, so she was concerned that the lightning created the cracks and sloped floor.

I have seen a lightning strike damage a house before. The lightning followed a root that went under a slab, vaporizing water in and near the root, which lifted the slab and foundation wall in the steam blast.

The slab floor in this current house was elevated on fill dirt. So a serious shake could have cause the slab to settle. And it did have a significant slope to about 12 feet of one end. After moving a bunch of furniture, I noticed that the chair rail was level, but the baseboard followed the slope of the slab. You might be able to make out the difference in the photo:

Craig DeWitt sloped floor.jpg

Now, baseboard following the same plane as the slab indicates that the baseboard was installed against a sloped slab. So, the sloped slab occurred long ago. (The homeowner indicated no remodeling in the 15 years while she has owned the house.) The slope was not related to a lightning strike, and the homeowner can't believe the floor had been sloped the whole time she owned it. But the evidence says it was. And it could have been a hardwood floor instead of carpeting. So watch for those pre-existing conditions.