Can asbestos block radon that’s outside? It is in my basement floor

No. Asbestos in your basement floor does not block radon coming from the soil outside or under the slab. Radon is a gas. It moves through tiny cracks, the floor wall joint, and any opening in the slab, and an old asbestos floor tile or sheet does nothing to stop it. The fix for radon is an active sub-slab mitigation system, and that runs $900 to $6,000, and most homes land around $1,950 to $2,250.

Let us walk through why.

Two different problems in one floor

You have two separate things going on. First, you may have asbestos in the floor material. Old vinyl tiles, the black mastic under them, and some sheet flooring used asbestos for decades. Second, you have radon coming up from the ground. These are not connected. One is a material in your floor. The other is a gas pushing up through the dirt beneath your house.

People mix them up because both live in the basement and both feel scary. But asbestos sitting flat on your floor is not a seal. Radon does not care about a layer of tile. It finds the gaps.

Where radon actually gets in

Radon comes from natural uranium in soil and rock. New Hampshire and Maine have plenty of it in our granite ground. The gas seeps up and your house pulls it inside, because warm air rising in the home creates suction at the bottom. That suction tugs soil gas right through:

• Cracks in the slab
• The floor wall joint where the floor meets the wall
• Gaps around pipes and the sump pit
• Bare dirt in a crawl space or fieldstone area

An asbestos tile floor has all of these paths around it and under it. It is not airtight. So it cannot block the gas.

What actually stops radon

The real fix is an active sub-slab depressurization system. We core a hole in the slab, run a pipe down into the gravel or soil under the floor, and put a quiet fan in line. That fan pulls the radon out from beneath the slab and vents it up and out above the roof, before it ever reaches your living space. For a dirt or fieldstone crawl, we use sub-membrane depressurization, where a sealed barrier goes over the soil and the fan pulls from under it. We install both kinds. Branden runs our radon work, and yes, the crew calls him B-Radon.

A radon system costs $900 to $6,000, and most homes land around $1,950 to $2,250. If you want a measured reading first, a radon test is $50, credited toward the job if you move ahead. Our radon mitigation carries a 10-year warranty. We do not put a radon-level number in writing unless it is spelled out in your agreement, because soil and weather move those readings around.

The asbestos part, plainly

If your floor has asbestos and it is intact and not crumbling, it is usually fine left alone or sealed over. Disturbing it is what releases fibers. We are a basement and foundation crew, not an asbestos abatement company, so if tiles need to come up we will tell you to bring in a licensed abatement contractor for that piece. We can plan the radon work around an intact floor in most homes, since the core hole is small and contained. [verify] on any case where the floor is already broken or flaking.

You do not need to rip out the whole floor to deal with radon. That is worth saying. The system works with your slab in place.

When to actually worry

EPA sets the radon action level at 4.0 pCi/L. They say to consider fixing between 2 and 4 (EPA). Above 4.0, you want a system. The only way to know your number is a test. A guess based on what your floor is made of is not a reading.

If you also have water issues down there, that is a separate job from radon. Water that pools at the foundation usually comes from disturbed backfill, the looser soil put back when your house was built. It drains slowly and holds water against the wall. That is what our Forever Dry System is for, and it is basement only. Radon and water can both be true at once, and we can look at both in one visit.

Get a real answer for your house

Call us at 603-610-1770 or book your free inspection. We will tell you what you have, radon, water, structure, or all three, and what each fix runs. Quote inside 24 hours. Free inspection, free estimate!

See our radon mitigation page, our crawl space services, and the 603 guarantee.

Related questions

Does sealing my basement floor get rid of radon? Sealing cracks helps a little, but it is not a real fix on its own. EPA notes sealing alone rarely brings radon down enough. You need an active sub-slab system to actually pull the gas out. A system runs $900 to $6,000, and most homes land around $1,950 to $2,250.

Do I need a radon test before mitigation? A test tells you your number and gives you a before reading. It is $50, credited toward the job if you move ahead. EPA action level is 4.0 pCi/L. If you are clearly high and want it handled, some homeowners go straight to mitigation, but a test is the clean way to start.

Can radon come up through a crawl space dirt floor? Yes, and a dirt or fieldstone crawl is one of the biggest radon paths. We use sub-membrane depressurization there, a sealed barrier over the soil with a fan pulling beneath it. See crawl space services.

Will a radon system stop my basement from being damp? No. A radon fan moves gas, not water. Damp from groundwater needs the Forever Dry System, full-perimeter drainage with a sump and dehumidifier. Different problem, different fix.