Actions to Reduce Radon
Reducing Radon Levels
For radon reduction work, you should always consider the use of contractors who are
certified (and trained) in a Radon Proficiency Program. We maintain a list
of contractors who are certified for radon mitigation by the
of Radon Scientists and Technologists (AARST),
(exit DHS) or the National Radon Safety Board, www.nrsb.org.(exit
DHS) For independent consulting on radon mitigation, call one of the
Radon Information Centers.
Sealing: Virtually all radon in Wisconsin comes from the soil
beneath houses. Radon at 300 to 1,000 pCi/L or more is in the gasses in the soil
under basement floors everywhere. Gaps and openings to soil through basement floors and
walls should be sealed with gas-tight materials. The caulk type with the best adhesion to
concrete is polyurethane (not silicone). However, experience by researchers has shown that
sealing cracks and openings in basements will result in reductions of radon by more than
50% in only about 20% of the houses in which it is applied. Since it can be
inexpensive and is part of the next method, it is worth a try, but one shouldn't expect it
will necessarily have a major effect. It might reduce radon levels significantly if the
area of openings that are sealed adds up to several square inches. Hairline cracks are not
Soil Depressurization is usually highly effective, reducing radon
to below 2
pCi/L. Air is withdrawn from beneath the basement floor with a
continuously-running fan in a 3 or 4-inch diameter pipe which exhausts at
roof level. This reduces the air pressure below the floor, so air in the
basement flows down to the depressurized zone, through small cracks and
openings that could not be sealed, instead of soil gases containing radon
flowing up into the basement through those openings. The State of
Wisconsin has distributed to all public libraries in Wisconsin copies of an
eleven-minute videotape, Radon Reduction: Sub-Slab Depressurization, showing
a system installed and how it works.
for a proficiency-listed contractor to install a system is usually around $1,200, and can
range from $800 to $2,000. Sub-slab depressurization is not a do-it-yourself project
unless you have considerable contractor skills.
For more information on reducing radon, consult the Radon Information Centers,
and with Certified Radon Mitigation Contractors.
Mitigation System Standards
get the radon as low as reasonably possible, maximize durability, and
minimize operating costs for homeowners, regulating states have adopted
standards for mitigation systems. The US EPA document,
Radon Mitigation Standards, (PDF, 1 MB) has been the model. In it, some of the most important
features for good mitigation systems are described in Sections14.2 (vent
pipe) (PDF, 212 KB), 14.3 (fan
installation) (PDF, 141 KB), and 14.5
(sealing) (PDF, 226 KB).
What does a radon mitigation system look like?
There are several online videos that will give you an idea of what is
typically done during the installation of a radon mitigation system:
(exit DHS) featured a
short segment that gives an overview on how to install a mitigation
- A brief animated video
(requiring Shockwave)(exit DHS) is at the State of Pennsylvania's radon
- Some radon mitigation supply
sources have pictures at their sites.
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December 18, 2013