Originally Posted by
Ariakas
I would say 200 is on the high side. I have a finished basement when I installed my radon mitigation system, I went with Great West Radon. I had to move some furniture so they can pull the carpet up in the far corners of the basement, they drill a hole and made sure the sub slab depressure was good with the fan they supplied. Ideally you should seal all cracks in basement but obviously not possible with finished basement, they sealed the cracks that's visible. My radon measured around 400 in basement, it gets worse in winter since windows are closed. I did the mitigation last Oct, I've been measuring since the mitigation and long term average is 10. I've seen days where my 1 day reading is 0. Another benefit is the basement is dryer in the winter and feels warmer as air is continuous sucked out from underneath the slab.