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Philadelphia

Epoxy and radon: the honest answer.

We coat basement floors for a living, so you might expect us to claim a coating solves radon. It doesn't. Here's what it contributes, what it can't do, and what to do first.

What the EPA actually says

Radon is a soil gas. It enters homes through cracks, joints, and openings in the slab and foundation. EPA guidance lists sealing those entry points as a standard component of radon reduction, and in the same breath says sealants and coatings alone have not proven to be a reliable standalone fix. Both halves of that sentence matter, and a contractor who quotes you only the first half is selling, not informing.

What a coated floor contributes

Our prep and system do genuine sealing work. Cracks get routed open, filled with rigid epoxy or polyurea, and sanded flush. The finished floor is a thick, continuous, non-porous membrane bonded across the whole slab. Fewer open paths through the concrete means fewer routes for soil gas through the floor. Treat that as a bonus on a floor you wanted anyway, not as mitigation.

What it doesn't touch: the sump pit, the floor-to-wall joint behind finished walls, the foundation walls themselves, and the pressure difference that drives gas into the house in the first place. That last one is why mitigation systems exist: they change the pressure under the slab so the gas never pushes in.

What to do first

• Test. Pennsylvania sits among the highest-radon states in the country, and the only way to know your number is a test kit or a monitor. They're cheap and the state lists certified testers.
• If the number is high, mitigate. A certified radon contractor installs the system. That's their trade, and we don't pretend it's ours.
• Coat the floor for floor reasons. The sealing benefit comes along free, and a mitigated basement with a coated floor is about as buttoned-up as a Philly basement gets.

The contractor who says "test your basement either way" is worth more to you than the one with the overclaim. We'd rather be the first guy.