We often get calls from homeowners saying they want to retest because they have “covered the sump pump” and the radon should be lower now. The sump pit can be a contributing source of Radon in a home. That is true. The problem arises when homeowners think they can “fix” this by covering the sump pit with a sheet of plywood or heavy plastic sealed with duct tape. In fact, a sump pit will need to be sealed but with a “Radon Resistant” cover installed by a Radon Mitigator. This is only part of the whole radon fix however. Typically, sealing the pit will only reduce radon levels partially. Radon has the ability to enter the basement of a home through foundation cracks and seams too small to be seen. The only way to prevent unhealthy levels of radon from entering a home that has tested high is by removing the radon from under the foundation or slab with a mitigation system.

We have had folks call and ask if “capping the PVC pipe installed in the basement for a mitigation system” will stop the radon from entering. I have tested several homes over the past few months that fall into this category. Yes, if you cap the pipe, the radon will be reduced. Unfortunately, it will not be reduce significantly. It has been our experience that you can expect about a 10 to 20% reduction. This is not enough in most cases to bring values below the 4.0 pCi/L action level set by EPA.

Another so called “fix” is painting the basement or applying a so called sealant to the basement floor and walls. Paint will not seal out radon. Sealants sold for this purpose are warned against by the State of Maine Radiation Control Program. You can read their full statement about sealants on their website, www.maine.gov/dhhs/eng/rad/hp_radon.htm.

We often speak with prospective buyers scheduling home inspections. Many times when we inquire if they want the radon in air test, they will inform us that they were told they did not need the test “because the home they are buying is on a slab.” This is a very dangerous myth. When a home is on a slab, the radon has nowhere to go but directly into the living space. We always recommend that homes built on a slab be tested just like a home on a full foundation or crawl space.