Radon Advice (Fairfax: houses, buy, construction)

[movingSomewhereThisSummer]

My wife and I are looking into a house. I asked about the radon system that is installed. The owner answered with the following:

The radon mitigation system is a fan-based, sub-slab depressurization system. The pipes were installed during the construction of the house. The fan, in the attic, was added in February 2006. There were 3 radon tests conducted in 2005/2006 with the first 2 conducted prior to the fan being added. Copies of the tests are available but the results were 7.0 & 7.4 pCi/L. After the fan was installed another identical test was conducted and the result was 0.8 pCi/L. Also, 3 sides of the basement slab were caulked. The 4th side was not caulked due to there not being any gap along that side. 2 photos are attached...1 of the radon tube in the basement and another of the fan in the attic.

Should we consider this house safe?

[saganista]

That's something you'll have to decide for yourself. Much of NoVa is susceptible to radon seepage from natural materials that have existed in the substrata for millions of years. Fairfax is a high risk area, Loudon and PW are only a little lower. Across the river, Montgomery County is a high-risk area with PG just a little lower. On the pCi/L scale, a rating of 4.0 is the sort of break point. 7.0 and 7.4 would be high but not absurd, given that numbers of 30.0 and higher are also found. Remediation, by exactly the means described, is on average 90% effective and the effect is generally durable so long as the remediation system is functional. Overall, you would likely be in better shape as far as radon goes by moving into this house with a remediation system than the house next door without one. A rating of 0.8 is essentially trivial, and it is not likely to have changed much since. Still, radon testing is relatively cheap. If it were me and I liked the hosue otherwise, I'd buy it, test it in five years, and then each ten thereafter. But, as I said, this is really a matter for you to decide.

[mdcrim]

All of the houses on my entire street (including my house) have radon remediation systems. Some areas of NOVA are susceptible to the radon seepage, hence the need for the remediation systems. If you're worried, just put in the offer with your normal inspections to include a radon inspection.