Crawlspace Encapsulations

Crawlspace Encapsulation

The subject of “how to keep a crawlspace dry” seems to be the question of the day.

As a home inspector (and project manager of extensive remodels), I have some thoughts that I think might be worth sharing. Here in middle Tennessee, there is clearly a humidity problem and that problem shows up in the crawlspace of nearly every home I inspect. It causes a myriad of issues that can cause significant damage and, in some cases, serious health issues. Unfortunately, newer homes are not exempt from the problem and the same “fix” is just as important with the new as it is with the old. I have seen 10 year old homes that are in worse condition than most 50 year old homes.

Over the years, many professionals have attempted to “fix the problem” but have failed miserably. From thin plastic vapor barriers with open or closed vents to vent fans that bring 95% humidity right into the crawl, contractors have mostly tried inexpensive simple fixes for a rather complex problem. Until recently.

Today, more and more contractors and businesses have begun the process of fully encapsulating the crawlspace which basically eliminates the destructive issues associated with high humidity and can literally SAVE a home. The catch is: IT MUST BE DONE CORRECTLY!

Here is the process I prefer and believe best protects your investment:

1. The existing fungal growth (mold) needs to be remediated. Not just sprayed or “bombed,” but sprayed with an anti-fungal solution and then cleaned, meaning every joist must be wiped down and the crawlspace throughly scrubbed. Only then should the encapsulation process begin.

2. The next step is to wrap every pier with a 12mil plastic and seal the seams with a very high tack sealing tape. I like to see the top edge sealed with a quality silicone or “Solar Seal.” After the piers are covered, the process of covering the floors and walls can begin. Once again, it’s imperative to seal every seam to avoid any possibility of moisture movement up from the crawlspace floor. This process is technically an encapsulation, but you can’t stop there and expect sufficient results.

3. You need the addition of a dehumidifier which will drastically lower the humidity to eliminate the ability for mold to grow. AND… it needs to be a high quality dehu that can run 24/7/365, if need be. The optimal setting would be 45-50% at the highest. My personal preference are dehumidifiers manufactured by AprilAire. I have one in my own home, and it has worked flawlessly.

4.The new building codes are requiring that the crawlspace and living space breathe together. This means that you need an HVAC supply and return in the crawlspace. It doesn’t have to be a large supply and return, just big enough to have good air transfer throughout the building envelope. The whole structure will benefit from the drier air.

In addition, the HVAC system will be more efficient, and you may find that there are health benefits also.

BTW… This doesn’t have to cost you an arm and a leg (unless you go with one of the big companies). There are a number of smaller reputable businesses out there that can do it all for a reasonable price. So take a serious look at a full encapsulation. Over the long run, it will prevent serious issues that can cause catastrophic damage to your home.

Rex Home Inspection.