We bought a house recently and our radon test came up as being high enough to install a radon system. I had 2 quotes. One company suggested that first I fill in the gap between the basement wall and the floor with concrete that is goes all around because there is a French drain installed. Then re-test for radon and my issue might be solved without needing a radon system.
Other company said not to fill that gap. I am hesitant as well. I don’t like the gap between the basement wall and the basement floor either but would it be wise to fill it up when it is there b/c of the French drain. Would we need to access that area again? Would the French drain not work properly because of we filled it up?
Any advice?
Replies
What are the details of your perimeter drain along the inside of the basement wall? was it put in because of water running down the basement walls? If so, this problem is not likely to have gone away.
If this was installed because of a high water table, and there is not any flow through the wall, you might be able to cover the drain, and some cover might be a good part of a radon mitigation system. with the gas detected, I would want it mitigated in any case. that stuff is not good for you.
I don't know much about why they installed the French drain. The info I have is that there was seepage- no idea if down the basement walls or a high water table. I have no idea who did the work- no permit pulled. Maybe to be on the safe side, I don't fill in that gap? I added a couple of pics
Looks to me like that gap was left on purpose. Very deliberate. Hints that the issue was water running down the wall.
You also do not know if the perimeter drain was installed allowing a path for gasses to freely flow from under the slab or wall or not. Is there a sump this drains into, or does it drain someplace else?
Could be the drain is made of gravel and slotted pipe, or it may be a drain only open to that gap.
So the inspector couldn't tell if it was connected to the sump pump. We don't know where it is connected and where it drains.. Someone suggested that we test the radon upstairs and if there is no radon upstairs then it might not matter.. as this is an old house and radon probably seeps everywhere and since we are living in the basement, it should be ok for now.
Since radon is the leading cause of lung cancer among non-smokers, you will want to at least provide good ventilation while you are living in the basement.
If you or anyone in your family smokes, it is even worse.
Can’t help, except to link to this similar discussion. https://www.greenbuildingadvisor.com/question/french-drain-w-radon-concerns
Thank you. I read the comments on that discussion. A lot if was very advanced for me. But still some good information. Thanks.