Radon Mitigation and New Construction Homes

Bob Wahl
Bob Wahl
Published on January 19, 2018

January is radon awareness month! Radon is a dangerous radioactive gas that can cause lung cancer. This is the final part of our 4-part series on radon with Tom and Cherie from St. Louis Radon Test and Mitigation Services and today we talk about radon mitigation and new construction homes.

Is there a way to test for radon before building? Can a radon mitigation system be installed as the home is being built? Who is responsible for the cost? Find out all this plus links to the previous three shows in this series on radon.

Can you test for radon before starting construction?

Unfortunately, you can’t effectively test the soil of a property to determine whether or not there’s going to be a radon problem. The radioactive elements like uranium that release radon do not cover an area like a giant blanket. There will be different pieces of these radioactive materials at different depths in the soil. The source must be strong enough to emit a substantial amount of gas and the source must have to have passageways through the ground leading from the source to the home. The home would also have to have a sufficient vacuum to suck up the gases into the living area. Because of all these factors, radon testing must be performed after the home is built.

How is radon testing on a new construction home done?

A new construction home is usually tested 2-3 weeks before closing. Typically, it’s up to the buyer to pay. Then the test and mitigation service will work with the builder to get access to the home. For an accurate result, they will place a continuous radon monitor in on Friday and pick it up Monday to test over the weekend, ensuring there are no workers or contractors going in and out.

If the results of the radon test are higher than 4.0 pCi/L, a radon mitigation system must be installed. There is usually a prearrangement between the builder and the buyer. Some builders will allow for the testing and will pay for the cost of the mitigation work, some builders will pay for a portion of the cost of the radon mitigation, or other builders will not pay for any of the cost at all. This will all have been agreed up front and most of the work will occur immediately after the closing of the home.

Can a radon mitigation system be installed during construction?

Commercial properties and apartment complexes will put in a system as they build without waiting for testing, but this is not common in Missouri when it comes to single family homes. Most builders want to avoid the extra costs, but if the radon mitigation system could be installed as part of the construction, the architect could better plan for its location. The electrician could install and electrical outlet in case a radon fan needed. The roofers could seal the vent at the top. This passive system alone would lower levels. Once the home is tested, they could determine whether or not a radon fan would be needed.

What is the cost?

We covered the cost in Part 3. If you missed it, the cost of installing a radon mitigation system will depend on the size and design of the home. Most radon system will run up to $1000, and usually fall within $750-$800.

Read Part I – What is Radon? 

Read Part 2 – Testing for Radon

Read Part 3 – The Installation Process of a Radon Mitigation System

Contact St. Louis Radon


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