How to fix high radon levels in a house
Fixing high radon usually requires hiring a professional to seal sump pits or bare earth and install a suction fan that vents the gas outside. Homeowners often try DIY fixes like caulking basement cracks or opening windows, but these methods fail to stop levels from spiking after heavy rain. The permanent fix costs thousands of dollars and can be difficult to install if a basement is filled with clutter.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from November 2026.
- This comes up 23.2× more often in r/HomeImprovement than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
How to fix high radon levels in a house
- 1Opening windows on multiple floors to temporarily lower radon levels with fresh air.Did this help you?
- 2Sealing concrete floor cracks and installing a sealed sump pump cover.Did this help you?
- 3Buying an electronic radon detector to monitor levels continuously.Did this help you?
- 4Hiring professional mitigation services to install vent pipes and fans.Did this help you?
- 5Buying a continuous digital monitor to track fluctuations instead of relying on a one-time test.Did this help you?
- 6Avoiding the basement or opening a window for fresh air when the monitor shows high levels.Did this help you?
- 7Attempting DIY mitigation by sealing the sump pit and caulking cracks in the basement floor.Did this help you?
- 8Paying a professional mitigation company to install an external fan and ventilation system.Did this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Their basement is filled to the brim with boxes and junk and everything. Can we fix the radon problem without moving stuff out?”source ↗
“Going through something similar in PA. Moved into a house 3 years ago. Didn’t test until this week. Basement was at 81 and upstairs living space 49. Tossed open windows on both floors.”source ↗
“I have moved into a house that does not have any history of testing or the ventilation system hooked up and I was curious if anyone has tested their home after symptoms or how they went about deciding to test and then the steps to fix the problem.”source ↗
“House I moved into was consistently testing over 300bqm. I got it mitigated about a year later, contractor sealed the sump pit with a bolted down cover, fixed a large diameter pipe to it with radon fan half way up, and out the side of the house.”source ↗
“Moved into a house and had a radon test done, was a little high, like 3.4. Had my home office in the basement for like 5 years before I decided to get a long term radon tester, turns out that the levels spike to 11 after rains and stay elevated for some time before falling back down to the 3-4 range. Better yet, when the level spikes in the basement it gets to 5 or 6 on the main floor. Tried to mitigate myself by sealing the sump pit and getting the radon caulk to caulk the cracks in the basement floor, it didn’t help. What ultimately helped was paying a couple thousand dollars to have a mitigation company come in and hook up the fan/vent.”source ↗
“We did an initial test that was sent in to a company, but after that decided to just get a high quality radon monitor and leave it in our basement full time. We did end up getting mitigation which involved covering up the bare earth under one part of the home, and then the installation of a system the sucked air up out of the basement and put it above the house.”source ↗
Where this came up
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