How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured and modular homes

Can I test vacant land for radon before building a house?

Wednesday, June 20, 2018

Not really. The average radon level of outdoor air is 0.4 pico-curies per liter of air (pCi/L), which is 10% of the level at which the Environmental Protection Agency (EPA) recommends remediation action. Some areas exceed the average, but we don’t know of any that even begin to approach the EPA’s threshold of 4.0 pCi/L. So air testing is impractical.

    While it is physically possible to test the soil and get a reading, high radon levels happen inside a home because of the accumulation of radon gas that rises out of the ground under all of the enclosed space. Soil testing requires four to eight tests at different locations around the future footprint of the home, which can get expensive. The test locations could miss a significant pathway and the site prep for the home may change the pathway characteristics under the home. Radon gas comes in through the small cracks in the floor and openings at pipe penetrations that are present in all homes, and the enclosure allows the gas to accumulate.

    You can test for radon in a home immediately after it is built. The natural settlement that occurs during the first two years will make small openings in the floor slab that may—or may not—increase the radon level somewhat after the initial settlement.

    One thing you can do is determine the odds that a home will have high radon once constructed by checking a Florida Department of Health radon data page at their website at:

    They have tabulated the percentage of homes in each zip code that have been radon-tested and exceed the level at which the EPA recommends remediation. So, for example, 33.9% of the homes in zip code 32607 have tested over 4.0 pCi/L, or about 1 in 3 homes. This statistic is not a predictor of whether a particular home will test high, only the overall likelihood. Also, some zip codes have not had enough testing for the Department of Health to publish a statistic.

    Another option is to install a “passive” radon system when the home is built, leaving open the possibility of adding a fan to the exhaust piping if testing after construction comes in high, to make it an “active” system. Doing a passive radon mitigation system while the house is under construction also enables all of the piping to be concealed, except where it penetrates the roof.

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Here’s links to a collection of our blog posts about “RADON":

What radon level is dangerous?

 Is a radon mitigation fan required to be on a dedicated circuit breaker/fuse in the electric panel?

What happens to a radon test result if the windows were opened, the test device moved, or there was any other evidence of tampering during the test? 

Where do I find the Florida laws regarding radon?

Can I test vacant land for radon before building a house? 

Is radon mitigation possible for a condominium?

Do radon mitigation systems require maintenance?

What is the average life expectancy of a radon mitigation system?  

Do older houses have higher radon levels than new houses? 

Can the seller tamper with a homebuyer's radon test to change the results?

How long does it take to get the results of a radon test? 

What is the danger of radon in well water?

What are the symptoms of radon poisoning? 

Does Florida have radon?

Where does radon come from? 

For how many years does an old radon test result remain valid?

Should homeowners get a pre-listing radon test before selling their home?

What are a homebuyer's options when the radon test comes back high (4.0 pico-curies/liter or more)? 

Do granite countertops emit radon?

How can I tell if a house has a radon mitigation system? 

Can a mobile/manufactured home have a high radon problem?

Do I need to test for radon when buying a condominium? 

What does a radon mitigation contractor do to lower the radon level in a home?

How can not testing for radon be an expensive mistake for homebuyers? 

Will the radon test come back sky-high in a house that has been empty and closed-up for months? 

What is radon? Should I be concerned about it?

Should I buy a house with a high radon level? 

What is the average radon level of indoor and outdoor air in America?

What is the operating cost of a radon mitigation system? 

• Should I buy a house with a radon mitigation system?

• Does the buyer or seller of a home pay for radon mitigation when the radon test comes back high? 

• What is the probability of having high radon in a Florida house?

• How quickly do I need to reduce a high radon level in my house? 

Does a home inspector check for radon?

What are the problems with underground return air ducts? 

• What is the probability of having high radon in a Florida house?

• What factors can change radon test levels up or down?

    Visit our RADON page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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