Solving Mildew/Mold in a North, VA home by Encapsulating the Crawl Space

Challenge

This homeowner contacted us because they were noticing mold or mildew growth in the closets of their home. This indicated to us that there was a significant moisture concern in the home. Approximately 50% of the air in a home comes from the crawl space. We began our inspection in the crawl space, looking for signs of moisture infiltration and microbial growth.

In the crawl space, we found mold/mildew growth on the floor joists and the paper backing of the fiberglass insulation. Insulation was falling from the floor joists, exposing the subfloor and resulting in energy loss and cold floors in the winter. The existing 6 mil vapor barrier was torn and unsealed allowing water vapor from the earth to rise into the crawl space and raise the relative humidity. Hot, humid, outside air has been flooding into the crawl space adding to the high relative humidity and warm temperatures, along with organic material, this is all mold needs to grow. Since homes are built naturally leaky, the warm, damp air is rising into the home and impacting the indoor environment and air quality, resulting in the moisture and microbial concerns in the home.

Solution

For this homeowner, we suggested encapsulating the crawl space to prevent outside air infiltration and control the relative humidity in the crawl space. This will help prevent microbial growth from occurring again and will help to reduce the humidity and moisture inside the home.

The first step of this project was to remove the damaged, dirty, moldy insulation, vapor barrier, and any debris. Then, we treated the wood substructure with Shockwave Antimicrobial. Shockwave is a hospital grade anti-microbial that is applied to affected surfaces and kills the mold.

Next, we installed a heavy-duty 10-mil vapor barrier that is durable enough to withstand service persons coming in and out of the crawl space as needed. The liner is wrapped and sealed around all piers and sealed to the crawl space walls 6-8 inches above outside grade. This allows any moisture that works its way through the wall to be directed beneath the liner to the earth instead of into the crawl space.

All vents, the rim and band, and sill plate are sealed to stop outside air from continuing to pour into the crawl space. Closed Cell Spray Foam is then applied to the crawl space walls leaving a 2” viewing strip at the top of the block wall. The viewing strip is a VA building code requirement for Termite Companies to perform their inspections.

We then installed a Friction Fit interior crawl space door that also provides an R-10 of insulation. This door can be installed behind an existing exterior crawl space door and both air seals and insulates, which is otherwise a very large hole for air to pour in.

We recommended the homeowner install a dehumidifier to ensure that the relative humidity is being controlled when it spikes over 55%, at 60% the potential for microbial growth occurs. However, at this time the homeowner opted not to install a dehumidifier.

We provided them with a Hygrometer which allows our homeowners to monitor the temperature and relative humidity of their crawl space from inside their home. This allows them to keep an eye on things so if there is ever a concern, we can catch it before there are problems in the crawl space.

This solution is helping our homeowner achieve their goal of maintaining a healthier indoor air quality and protecting themselves and their home from humidity and microbial growth as well as helping to reduce energy bills in the home.