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Effectively Handling Vapor Intrusion in a Building or Home

One of the major environmental risks facing homeowners is vapor intrusion. The process of vapor intrusion is caused by contaminated soil or groundwater that lies beneath a house's foundation. The contaminants located beneath a home can slowly migrate into the structure, which can have a negative affect the overall indoor air quality. Any type of opening in the foundation or walls of a basement is a potential source of vapor intrusion in a house. There are several different pollutants that can affect homes via vapor intrusion, including volatile organic compounds (VOCs), radon and mercury.

The accumulation of these compounds in a home due to vapor intrusion presents several potential hazards. Short term exposure to high levels of contaminants can cause health problems, breathing difficulties and even pose a safety hazard in the case of explosive compounds. High levels of pollutants can also produce foul odors in the home, which are most noticeable on the lower floor or in the basement. Long term exposure to low levels of contamination from vapor intrusion is believed to potentially cause chronic health conditions. Accumulation of airborne pollutants due to vapor intrusion requires swift and effective treatment to ensure the highest air quality indoors.

One of the most effective mitigation methods for vapor intrusion problems is sub-slab-depressurization. This process allows an exit point for the pollution entering from vapor intrusion. A vent pipe is installed through the basement floor, or the slab foundation in an above grade home. Most often, a four inch PVC pipe is installed through the concrete slab and a small area of the soil or substrate beneath the house is removed to produce a chamber under the hole.

Once the vent pipe is installed in the floor, additional PVC tubing is used to direct the flow of air to the highest point in the home, typically in the attic. A strong fan is attached to the end of the tubing, which creates suction to draw the harmful vapors outdoors and counteract the vapor intrusion. The size of fan that is required is determined by the type of soil the house is built on and the total length from the vent pipe to the fan. The exhaust of the fan is routed outside, above the roof and away from any operable windows to prevent the risk of the contaminants entering back into the home.

After the installation of a sub-slab-depressurization arrangement, cracks and gaps in the foundation should also be addressed to fully minimize the impact of vapor intrusion. Most basements have some cracks due to settling and holes from the entry of utility lines. These areas should be carefully sealed in order to provide the most effective reduction in vapor intrusion.

Vapor intrusion is a serious problem for a homeowner, and must be treated carefully to assure the highest air quality possible. Utilizing sub-slab-depressurization is a practical and efficient way of handling vapor intrusion. This venting method produces the best results out of the available options for treating vapor intrusion. When properly installed, this system drastically reduces the effects of vapor intrusion and improves the indoor air quality.

Vapor Intrusion Abatement Specialists