Crawl Space Management


I recently inspected another crawl space for a friend, in response to an outrageous quote from a local company to fix his “problems with mold, water infiltration and poor air circulation.” This company used numerous scare tactics in their report to promote the conversion of his crawl space from the current “vented” system, to a “conditioned” crawl space – all for a mere $10,000 or so. Most of these expensive solutions are unnecessary to solve the typical crawl space problems.

I do think that the old “vented” crawl space is probably not the best method to use going forward. However, I also think that the “conditioned” crawl spaces being heavily promoted today are probably overkill. A middle of the road solution is to use a “closed” crawl system that still utilizes insulation in the floor system, in conjunction with a sheet of plastic on the ground, no vents in the outside foundation walls, and a few strategically placed air supplies run off your first floor A/C system. All this only costs about $500 more than a vented crawl. A fully conditioned crawl usually costs $5,000 – $8,000 more. Additionally, most existing houses can be retro-fitted fairly easily without incurring significant costs.

The basic problem with vented crawl spaces is that warm, humid air becomes trapped under your house in the summer time, giving rise to potential mold growth. By closing off the outside vents you prevent the humid air from getting under the house, but you leave yourself with a need to circulate the remaining air. You could simply install a couple fans and a dehumidifier from Lowes, all running off an extension chord, and that would be sufficient for most houses. In fact, this is exactly what I do during the construction process prior to being able to turn on the A/C sytem. However, this requires routine monitoring to ensure that everything is functioning properly and most people don’t like to go under the house. Therefore, the optimal permanent solution is to actually put air supplies in the crawl space so that you are blowing cool air into the crawl. This not only circulates the air, it also functions as a dehumidifier. Most of the time, this simple system will make a huge difference in the conditions under your house as well as helping to minimize bugs and spiders. The air being pumped under the house is minimal in relation to the benefits derived.

I have been using this system for several years now and have made a point of checking the results from time to time in most of those houses to see how the system works. In every case, it has performed better than expected.

Next time you hear someone complain about crawl space problems, have them e-mail me and I will forward them as much information as they want on how to deal with the issue in a cost effective manner. If you have specific questions that I have not addressed feel free to do the same.