Hardwood Floors August/September 2018

By Bobby Parks

FIGURE 1: A vented crawlspace with a foam protected floor compared to an unprotected floor.

• How permeable is the interior oor system? • How humid is the outdoor air? is varies greatly with geography and is probably the most prevalent factor. • How cold do the occupants like to keep their home? e colder the home, the worse the problems will be and the sooner it will show itself. HVAC PROFESSIONALS — THE MOISTURE FROM WITHIN And then there is the A/C guy. Many years ago, building code professionals realized the importance of the Manual J load calculations and ge ing the HVAC systems sized properly. e tighter and be er insulated we build our buildings, the more critical it is to get this part right. Of course, the A/C guy o en thinks “bigger is be er” (guess it’s just a man thing). As a

one area where it could be covered with 2” of the closed cell foam. In another area (but under the same room above), I intentionally le a “holiday” and inserted a second data logger. I also have a data logger in the room above monitoring the temperature and humidity above the test area. As you can see, in just the rst month of summer in Louisiana, the oor with the closed cell foam is consistently maintaining 10-11 percent relative moisture content (which is excellent for this part of the country). On the other hand, the section of ooring le exposed has already risen above 27 percent and can be expected to continue to rise, reaching its peak in September before the seasonal change will help to reverse the drying potential. My conclusion: in a vented crawl space, we must incorporate both thermal protection and exterior vapor protection or the moisture can wreak havoc, depending on the following three factors:

the magazine of the national wood flooring association

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