Blog/Opinion: Are You Radon Savvy?

Radon is a radioactive gas that is often found in the soil. It can get into a house by diffusing through the solid materials making up the foundation. It can also enter a house if there is an air-pressure difference to pull it indoors through random cracks or holes in the foundation. As with above-ground moisture and pollutant transport, air-pressure differences move significantly more radon indoors than diffusion—often one-hundred times more.

 

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It’s also possible for the raw materials making up a foundation to release radon directly into the interior of a house. However, radon in building materials seems relatively rare in the U.S. It is more prevalent in Europe. A variety of radon-reduction techniques can be found in various publications available through the EPA. Radon reduction usually involves one or more of the following mitigation strategies, each of which has several variations:

• Sealing cracks and pathways that air-pressure differences push or pull radon through.
• Manipulating air-pressures in, or under, a house so radon won’t be pulled through the cracks and pathways that can’t be sealed.
• Increasing the ventilation rate in the house to dilute the concentration of radon that does enter the living space.
  

It’s very difficult to predict if a particular house will have a radon problem—you must actually perform a test and measure the radon level in the indoor air. At that point, the house can be evaluated to determine which mitigation measures will work the best. If you’re planning to build a new house, you can’t perform such a test until the house is complete so, during the design phase, it makes a great deal of sense to plan for some simple radon mitigation—whether you think you’ll need it or not. It rarely costs much to do so and, if you end up with a high indoor radon level, it makes it very easy to remedy the situation. If you don’t end up with a high radon concentration in the completed house, you really haven’t invested much money. Most people consider the minor expense to be cheap insurance.

 

If it is done while a house is being built, roughing in a sub-slab radon depressurization system might add no more than $300-500 to the cost of a house—if a builder is familiar with the installation of these systems.

 

The mechanisms that allow radon to enter a house can also cause other VOCs to enter as well, such as metabolic gases from soil microbes, termiticides, lawn chemicals, chemicals found in hazardous landfills, contaminated ground water, and hydrocarbon spills.

 

Sealing Cracks

 

There are many possible pathways for radon (and other soil gases) to follow to get into the living space. Covering exposed earth in basements and crawls spaces will help block radon’s entry. One of the best materials to use is a continuous layer of concrete—as long as it is crack-free. Plastic barriers can do the job if they are well-sealed at all seams and around the perimeter with mastic.

 

Sump pump pits should be fitted with a sealed cover because radon can get into drain tiles and enter a basement through a sump pit. Sealing cracks and openings in floors and walls, or where plumbing or electrical lines enter a basement below grade, is also helpful. Radon can get inside concrete-block walls, so sealing the open cores at the top of a concrete-block wall can prevent its escape into the basement.

 

Manipulating Air Pressures

 

A number of factors can lead to a depressurized house (e.g. leaky ducts, chimneys, exhaust fans, etc.), all of which can contribute to radon being pulled indoors. By installing a dedicated make-up-air supply for air to enter, rather than allowing it to enter through the random cracks, depressurization can be minimized. Sealing leaky ducts can also help a great deal.

 

Of course, ventilation is another way to reduce radon levels.

 

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(Note: The views expressed in this blog post are those of the author, and do not necessarily represent those of The Healthy House Institute, LLC.)

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