Dirt Crawlspaces Make People Sick

When you vent crawlspaces you bring in hot, humid air and cause moisture and mold problems. Moisture moves to the cold surfaces. Venting crawlspaces made sense only when you had no air conditioning and no insulation and no crawlspace walls. - RLC Engineering Clemson, SC

From thermal, moisture, structural, occupant health, financial and operational standpoints, sealed crawlspace foundations perform better in my opinion than vented crawlspaces. Essentially all other building science experts around the country also hold this opinion.(Reference: Energy and Environment Building Association) - Craig Dewitt, PhD

Thousands of homes each year, in the Southeast, are built with vented dirt crawlspaces and yet virtually all building science experts agree that vented dirt crawlspaces are a bad idea.

The word “dirt” is the problem. The unsealed dirt allows mold, moisture, wood rot, radon, and soil gases to make your crawlspace and home unhealthy. The foundation vents actually add more moisture to the crawlspace and cost you about 15% more on your power bill.

Mold is always in the dirt. Moisture and evaporation causes the mold to grow and allows ideal conditions for mold growth and eventual wood decay in the subfloor. In short the house actually becomes sick, which means people in the house can get sick.

Your house may be your biggest investment, but ask yourself this question
“Which is more important, your home or the health of everyone living in your home?”

How does the unsealed dirt crawlspace do it’s damage?

Water in the crawlspace is not the main problem. Moisture in the dirt, from the foundation vents, and the water table underneath the house causes evaporation which increases the relative humidity. Now you add mold and other contaminants from the dirt floor of the crawlslpace and you have created the toxic stew. Mold now has the three things it needs to grow – the food source (the wood floor), moisture, and adequate temperature.

If this problem is not corrected, the wood floor will eventually begin to rot. In terms of health, however, the mold is your real enemy..

The areas in RED indicate the regions that will experience extreme benefits from a Sealed Crawl Space over a traditional vented crawl space. Sealed Crawl Spaces are highly recommended for areas covered by the BLUE portions. Areas on this map shaded in GREEN will also benefit from a Sealed Crawl Space.

Foundation vents

The only reason crawlspaces have foundation vents is because of the dirt under the house. Think about it, if you had a fully finished basement with sofas and a big screen TV, there would be no foundation vents, because the builder knows that the vents would allow mold and moisture inside and contaminate the entire basement. There is no dirt floor because the concrete slab separates the dirt from the basement and it works just fine and protects the home. Foundation vents are a dead give a way that there is dirt in the crawlspace. Dirt means vents, no dirt means no vents. The dirt is the problem.

In the summer, outside hot humid air comes into the crawlspace thru the vents. When it is raining the situation is even worse. Most crawlspaces have air conditioning ducts allowing the hot humid air and the evaporation from the dirt of the crawlspace to hit dew point near the cool air ducts and condensation results. This condition now allows mold from the dirt below an ideal environment to begin growing on the subfloor and wood supports of the house. Eventually wood rot can ruin the subflooring and joists.

There are three types of mold groups; primary, secondary, and tertiary. As mold gets established, the more toxic ones often begin to set in. The wood floor allows air and toxic mold to move right into the house, but even worse all air conditioning ducts leak and blow soil gases and mold evenly throughout the house.

Why would anyone ever build a house over dirt in the first place? It is cheaper than a concrete floor. The damage to the house and people living in the house is never worth a cheap dirt crawlspace. In fact, every dirt crawlspace needs to be completely sealed or encapsulated to prevent all of these problems permanently.

Stack Effect

Does air just happen to move from the crawlspace in to the house? Actually all buildings operate off of the same principle called the “Stack Effect”. That means that normal air flow moves from the bottom and sides to the top. 40 -50% of the air in the house at any given time is from the crawlspace. Obviously, this allows mold and other contaminants to move right into the house.

Some of the Negative Effects of a dirt crawlspace:

• Toxic Mold
• Bugs, dust mites, and rodents
• Odors in upholstery and carpets
• Swollen doors and windows
• Cupping wood floors
• 15% increase in power bills (approximate)
• Health risks from allergies to cancer

Crawlspace Encapsulation is the only real solution to the dirt crawlspace and could be the most important decision you ever made with home ownership. Our first priority at PureAir Systems is insulation removal and wood treatment of the subfloor and joists and any other wood structures. The wood is at first properly cleaned and then we apply our permanent adhesive mold block. This protects the wood against mold and wood decay with a 25 year warranty.

Our first priority at PureAir Systems is insulation removal and wood treatment of the subfloor and joists and any other wood structures. The wood is at first properly cleaned and then we apply our permanent adhesive mold block. This protects the wood against mold and wood decay with a 25 year warranty.

BEFORE Insulation removed, mold treatment with 25 year guarantee all prior to Encapsulation	AFTER Crawlspace wood mold treatment with Encapsulation

Next we remove debris from the dirt floor and treat it with an anti-microbial solution. At this time a super sump pump can be added if necessary. Once the dirt is prepared we encapsulate it with the PureAir white crawlspace liner to all piers, foundation walls, etc. so that the crawlspace is sealed better than a concrete slab. We use exclusive nail hangers on the walls and then seal all the edges with liquid adhesive mastic and seam tape.

When everything is finished we seal up the crawlspace vents from the inside. As the system operates, duct leakage in the crawlspace will condition the crawlspace area, keeping it dry. In rare cases a dehumidifier can be added.