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A Homeowner's Guide to Reducing Indoor Radon Gas or Radon in Water
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
This article explains the impact of radon gas contamination levels in air or water on real estate sales and property values. This article series includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Radon Mitigation Systems: How to Perform Radon Remediation to Remove Harmful Levels of Indoor Radon
See RADON HAZARD TESTS & MITIGATION for details about radon in buildings, its health effects, how to measure radon, the effect of radon contamination on real estate values and home sales, and a guide on how to remove radon from buildings. Also see ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY for our full list of environmental hazard identification and remedy related to buildings. As reported in Best Practices Guide to Residential Construction:
The EPA and the U.S. Geological
Survey have rated every county in the United States as Zone 1 to 3 for radon risk. Links to state maps with county by-
county risk levels can be found at www.epa.gov/
radon/zonemap.html.
The EPA recommends that all homes
in Zone 1 counties be built with radon-resistant features,
which can be easily upgraded to a radon remediation system
if needed.
Since homes in Zones 2 and 3 can also have
high levels, it is best to check with your state radon office
to see if they are aware of any local “hot spots.”
The techniques for radon-resistant building vary for
different foundation types and site conditions, but all contain
the six basic elements described below.
Following
these steps creates a passive soil depressurization system, which sufficiently lowers radon levels in about 50% of
homes requiring mitigation.
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If radon levels need to be lowered
further, the system can be easily converted to an active
system by adding an inline fan, which can meet the
target levels in nearly all cases (see Figure at above left, showing a typical radon mitigation system installation). The goal
of radon remediation is to lower the average indoor radon gas level to less
than 4 pCi/L, and preferably 2 pCi/L.
- Radon Gas permeable layer. This is usually a 4-inch layer of
clean, course gravel installed beneath the slab for
drainage, but which also allows the gas to move freely
beneath the house. In areas where native soils are
sufficiently permeable to build on, a loop of perforated
pipe inside the footings is an option, and may also
serve as a drain tile.
The perforated pipe should be
about 12 inches in from the foundation wall and 1 inch
below the slab, with a minimum diameter of 3 inches
for slabs under 2,000 sq ft and 4 inches for slabs up to
4,000 sq ft. Where subgrade soils are compacted or
frozen, another option is to use geotextile drainage
mats to create a gas-permeable layer on top of the
subgrade but beneath the slab.
- Plastic sheeting to Stop Radon Gas Penetration. Lay minimum 6-mil polyethylene
sheeting (or 3-mil cross-laminated sheeting) on top of
the gas permeable layer. This helps keep soil gases
from entering the home and also keeps concrete from
clogging the gravel layer. Overlap seams by at least
12 inches, and repair any punctures or tears with tape
or a patch of sheeting material.
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A post mitigation radon test of 2 to 7 days should be
done within 30 days of system installation. For an accurate
reading, all windows and doors must be closed
12 hours before and during the test, except for normal use
for entry and exit.
-- Adapted with permission from Best Practices Guide to Residential Construction.
See Radon Enviro-Scare for a full discussion of the normal cycle of public fear that accompanies the discovery and publicity of various environmental hazards, including radon gas and see Enviro-Scare, the Cycle of Public Fear for our article about consumer environmental safety worry cycles that change over time.
For a Thorough Background in Radon Hazards, Radon Mitigation, & the History of Radon Concerns in the U.S. also see these articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
- "Radon's Threat Can Be Subdued", part 1 - William Turner, Terry Brennan, Solar Age Magazine Radon and its progeny are the slipperiest pollutants in the indoor environment, but there are simple ways to keep radon and its relations at bay.
- "Radon's Threat Can Be Subdued", part 2 - what is radon, where does radon come from, how does radon get indoors, and why is radon a problem in buildings.
- "Radon's Threat Can Be Subdued", part 3 - standards for airborne radon levels in buildings and recommended levels of radon for action, how radon is best detected, and radon action plan.
- "Radon's Threat Can Be Subdued", part 4 - radon prevention advice for new construction, radon in well water - how it is removed, sources of information about radon gas and radon contamination.
- "Defeating Radon" part 1- Terry Brennan, Bill Turner, Solar Age Magazine - How does radon get into buildings, how do I know if a building has a radon gas problem, how can I solve radon problems in existing homes, and what can I do to prevent radon from entering new homes. Part 1: where Radon comes from, how to diagnose radon
- "Defeating Radon" part 2- Guide to keeping radon out of new houses - design details
- "Defeating Radon" part 3- Key spots to seal, to stop radon gas leaks into buildings
- "Defeating Radon" part 4- Data on radon levels in buildings before & after radon mitigation treatment
- "Defeating Radon" part 5- Air filtering, testing after radon mitigation, where to buy radon tests
Also see "Radon Basics", Q&A article, Solar Age, April 1984, includes advice for radon-resistant construction for an underground house built of concrete
Frequently Asked Questions (FAQs)
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- RTCA, the Radon Testing Corporation of America, is in Elmsford, NY - 800-457-2366
- "Radon Basics", Q&A article, Solar Age, April 1984, includes advice for radon-resistant construction for an underground house built of concrete
- "Radon Basics-PDF", Q&A article, Solar Age, April 1984, includes advice for radon-resistant construction for an underground house built of concrete
- Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.
Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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