Spray Foam Insulation in a Carrollton, VA Crawl Space
Challenge
This Carrollton, VA homeowner reached out to us because they were interested in replacing the fiberglass batt insulation in their crawl space with spray foam. They were interested in not only making the home more energy-efficient but also making it more comfortable.
At our inspection, we found that moisture and humidity had been a concern in this crawl space. There were mildew and mold growth on the joists and damage to the fiberglass insulation. As moisture and humidity collect in the crawl space, materials such as batt insulation and the floor joists absorb this moisture. The fibers of the insulation have begun to pull apart from one another due to the water it is holding. This results in the stalactite effect, or “dripping” insulation. The moisture in the insulation is also being held against the metal rods holding the insulation in place. These rods eventually rust and break, because the insulation has become so heavy from the retained water it sags and falls.
The vapor barrier in this crawl space was laid over most of the ground but was not sealed to itself, piers or the walls. The unsealed barrier allows moisture to rise from the ground and into the crawl space environment. We also found mineral deposits on the liner indicating that some puddling had occurred on top of the barrier.
We also found that the open vents in the crawl space were very low to the outside grade. This indicated that not only are they letting in hot, humid air, but they potentially could be allowing bulk water intrusion.
Solution
The first step in this crawl space is to clean out the existing vapor barrier, insulation, and any debris. The homeowner opted to complete this step themselves. Our team then applied Shockwave antimicrobial to the wood surfaces in the crawl space. Shockwave is a hospital-grade antimicrobial designed to kill microbial growth.
The homeowner had little traffic and equipment in their crawl space, so they opted to have us install a 10-mil CleanSpace Light vapor barrier. This barrier is durable enough to withstand any necessary crawl space inspections. We overlapped and sealed all seams, attached and sealed the liner to the foundation walls, 6 inches above outside grade, and wrapped and sealed all piers. This sealed the crawl space from rising water vapor from the earth.
We then sealed the rim and band, sill plate, and all vents with foam. This is a key step in air sealing the crawl space and preventing outside air and humidity from entering the space. We then applied Closed Cell Spray Foam to the crawl space walls at an R-10, leaving a 2-inch viewing strip at the top of the block wall. The viewing strip is a requirement of the VA Building Code and allows for termite companies to do their annual inspections.
At this time, the homeowner opted out of installing a dehumidifier and instead had a pressurization fan installed with a passive return to circulate air. We installed a Hygrometer to allow the homeowner to continue to monitor the relative humidity and temperature in the crawl space. The Hygrometer will allow them to watch the climate changes in the crawl space and indicate if and when a dehumidifier will be necessary to control the relative humidity. We do not want the relative humidity to increase over 60%, because at that point the potential for microbial growth occurs.
These steps will give the homeowner a more controlled space under their home and the tools they need to help prevent microbial growth from occurring again. Sealing and insulating the crawl space provides the added benefits of improved indoor air quality, lower energy bills, and warmer floors in the winter.
