Radon for Real Estate Case Study
We had to reduce the radon levels in a house for a real estate transaction that was approximately 40 times greater than the action level at a level of 80. The home inspector tested two areas of the house following the protocol to test every 2,000 square feet. He tested the theater room (88.4) and the bunk room (79.3). The tests for this large house had a footprint of 4,500 feet on the main level and 4,500 in the basement.
Normally a radon mitigation systems are designed to accommodate 2,000 square feet. The builder has stated he installed a passive system with a single exhaust through a 4” ABS drain waste vent pipe. This was woefully inadequate.
We proposed a phased approach. First, we would install a standard high volume fan. If necessary we would install two external fans attached to copper downspouts. A copper downspout is approximately ten times more expensive than aluminum.
After the first phase was installed phase the levels were reduced from 80 to 20 pCi/L. Still not at the EPA average of 4 which is the action levels for houses. We then install a higher suction fan but this fan was too noisy. If you reduce the size of the exhaust pipe and do not compensate with lower suction the systems will get noisier.
We installed a second system near the bedroom. This reduced the theater room to 1.1 and the bunk room to 5.2. We had to put a second suction point near the bunk room. The levels in the theater room were 0.9 and the bunk room 1.1. The additional suction points added more suction, kept the house quieter and was effective.
If you use 4” drain tile there is a limit to its effectiveness. You need to do this to eliminate the noise of the fans.