If the Radon level
is above is 4 pCi/L or more fix your home. There are several methods, ways to
mitigate, and lower the radon levels in your home. Some techniques prevent radon
from entering your home while others reduce radon levels after it has entered.
Your house type will affect the kind of radon mitigation system that will work
best. Houses are generally categorized according to their foundation design such
as basement, slab-on grade (concrete poured at ground level), or crawlspace (a
shallow unfinished space under the first floor). Some houses have more than one
foundation design feature. In these situations a combination of radon reduction
techniques may be needed to reduce radon levels.
In Basement and
Slab-on-Grade Houses, radon is usually reduced by one of four types of soil
suction: sub-slab suction, drain tile suction, sump hole suction, or block wall
suction (also called sub-slab depressurization) is the most common and usually
the most reliable radon reduction method. One or more suction pipes are inserted
through the fl oor slab into the crushed rock or soil underneath through the
house thru the roof. They also may be inserted below the concrete slab from
outside the house. The number and location of suction pipes that are needed
depends on how easily air can move in the crushed rock or soil under the slab,
and on the strength of the radon source. Often, only a single suction point is
needed. A radon vent fan connected to the suction pipe(s) draws the radon gas
from below the house and releases it into the outdoor air while simultaneously
creating a negative pressure (vacuum) beneath the slab. Common fan locations
include unconditioned house and garage spaces, including attics, and the
exterior of the house.
suction is the same as active sub-slab suction except it relies on natural
pressure differentials and air currents instead of a fan to draw radon up from
below the house. Passive sub-slab suction is usually associated with radon
resistant features installed in newly constructed homes. Passive sub-slab
suction is generally not as effective in reducing high radon levels as active
Some houses have
drain tiles or perforated pipe to direct water away from the foundation of the
house. Suction on these tiles or pipes is often effective in reducing radon
levels. One variation of sub-slab and drain tile suction is sump hole suction.
Often, when a house with a basement has a sump pump to remove unwanted water,
the sump can be capped so that it can continue to drain water and serve as the
location for a radon suction pipe. Block wall suction can be used in basement
houses with hollow block foundation walls. This method removes radon and
depressurizes the block wall, similar to sub-slab suction. This method is often
used in combination with sub-slab suction.
method to reduce radon levels in crawlspace houses involves covering the earth
floor with a high density plastic sheet. A vent pipe and fan are used to draw
the radon from under the sheet and vent it to the outdoors. This form of soil
suction is called sub-membrane suction, and when properly applied is the most
effective way to reduce radon levels in crawlspace houses.
less-favorable option is active crawlspace depressurization which involves
drawing air directly from the crawlspace using a fan. This technique generally
does not work as well as sub-membrane suction and requires special attention to
combustion appliance back-drafting and sealing the crawlspace from other
portions of the house.
In some cases,
radon levels can be lowered by ventilating the crawlspace passively (without the
use of a fan). Crawlspace ventilation may lower indoor radon levels both by
reducing the home’s suction on the soil and by diluting the radon beneath the
house. Passive ventilation in a crawlspace is achieved by opening vents, or
installing additional vents. In colder climates, for either passive or active
crawlspace ventilation, water pipes, sewer lines and appliances in the
crawlspace may need to be insulated against the cold. These ventilation options
could result in increased energy costs due to loss of conditioned air from the
reduction techniques that can be used in any type of house include: sealing,
house/room pressurization, heat recovery ventilation, and natural ventilation:
and other openings in the foundation is a basic part of most approaches to radon
reduction. Sealing the cracks limits the flow of radon into your home thereby
making other radon reduction techniques more effective and cost-effi cient. It
also reduces the loss of conditioned air. The EPA does not recommend the use of
sealing alone to reduce radon because, by itself, sealing has not been shown to
lower radon levels significantly or consistently. It is difficult to identify
and permanently seal the places where radon is entering. Normal settling of your
house opens new entry routes and reopens old ones.
pressurization uses a fan to blow air into the basement or living area from
either upstairs or outdoors. It attempts to create enough pressure at the lowest
level indoors (in a basement for example) to prevent radon from entering into
the house. The effectiveness of this technique is limited by house construction,
climate, other appliances in the house, and occupant lifestyle. In order to
maintain enough pressure to keep radon out, the doors and windows at the lowest
level must be left closed, except for normal entry and exit. This approach
generally results in more outdoor air being introduced into the home, which can
cause moisture intrusion and energy penalties. Consequently, this technique
should only be considered after the other, more common techniques have not
sufficiently reduced radon.
Ventilator (HRV), also called an air-to-air heat exchanger, can be installed to
increase ventilation which will help reduce the radon levels in your home. An
HRV will increase ventilation by introducing outdoor air while using the heated
or cooled air being exhausted to warm or cool the incoming air. HRVs can be
designed to ventilate all or part of your home, although they are more effective
in reducing radon levels when used to ventilate only the basement. If properly
balanced and maintained, they ensure a constant degree of ventilation throughout
the year. HRVs can also improve air quality in houses that have other indoor
pollutants. There could be significant increases in the heating and cooling
costs with an HRV, but not as great as ventilation without heat recovery.
ventilation occurs in all houses. By opening windows, doors, and vents on the
lower floors you increase the ventilation in your house. This increase in
ventilation mixes outdoor air with the indoor air and can result in reduced
radon levels. However, once windows, doors and vents are closed, radon
concentrations often return to previous values within about 12 hours. Natural
ventilation in any type of house should normally be regarded as only a temporary
radon reduction approach because of the following disadvantages, loss of
conditioned air and related discomfort, increased costs of heating or air
conditioning and security concerns.Lowering high radon levels requires technical
knowledge and special skills.
Lowering high radon levels requires
technical knowledge and special skills. You should use a contractor who is
trained to fix radon problems. A qualified
contractor can study the radon problem in your home and help you pick the right
treatment method. If you are considering fixing your home’s radon
problem yourself, you should first contact your "State Radon Office" for guidance and
Note: This diagram is a composite view of several mitigation options. The typical mitigation system usually has only one pipe penetration through the basement floor; the pipe may also be installed on the outside of the house.
Radon resistant techniques work. When installed properly and
completely, these simple and inexpensive passive techniques can help to reduce
radon levels. In addition, installing these when constructing a house makes it
easier and less costly to activate the system to reduce levels further, if the
passive techniques don’t reduced levels below 4 pCi/L. Radon-resistant
techniques may also help to lower moisture levels and other soil gases.
In a new home, the cost to install passive
radon-resistant features during construction is usually between $350 and $500.
In some areas, the cost may be as low as $100. A qualified mitigator will charge
about $300 to add a vent fan to a passive system, making it an active system and
further reducing radon levels.
Radon-resistant techniques (features) may vary for different
foundations and site requirements. If your new house was built (or will be
built) to be radon-resistant, it will include these basic elements:
This layer is placed beneath the slab or fl ooring system to allow
the soil gas to move freely underneath the house. In many cases, the material
used is a 4-inch layer of clean gravel. This gas permeable layer is used only in
homes with basement and slab-on-grade foundations, and not in homes with
Plastic sheeting is placed on top of the gas-permeable layer and under the slab
to help prevent the soil gas from entering the home. In crawl spaces, the
sheeting (with seams sealed) is placed directly over the crawlspace floor.
Sealing and Caulking:
All below-grade openings in the foundation and walls are sealed to reduce soil
gas entry into the home.
Vent Pipe: A 3 or
4-inch PVC pipe (or other gas-tight pipe) runs from the gas-permeable layer
through the house thru the roof, to vent radon and other soil gases to the
Junction Boxes: An
electrical junction box is included in the attic to make the wiring and
installation of a vent fan easier if you decide to activate the system. An alarm
is installed along with the vent fan to indicate when it is not operating
built to be radon-resistant, every new home should be tested
for radon after occupancy. If you have a test result
of 4 pCi/L or more, add a vent fan to the passive system to make it an active
system and further reduce radon levels.
RADON in WATER
If you’ve tested
and have a radon in water problem, it can be easily fixed. Your home’s water supply can be
treated in one of two ways:
treatment for the whole
house can effectively remove radon from the water before it enters your home’s water distribution
system. Point-of-entry treatment usually employs either granular activated carbon
(GAC) filters or aeration systems. While GAC filters usually cost less than
aeration systems, filters can collect radioactivity and may require a special method of
treatment devices remove
radon from your water at the tap, but only treat a small portion of the water
you use, e.g., the water you
drink. Point-of-use devices are not effective in reducing the risk from breathing radon released
into the air from all water used in the home.
INSTALLATION and OPERATING COSTS
typical cost ranges provided by the EPA as of Dec. 2006. Many factors can affect
this so only use them as a guideline, your actual costs may vary. The fan electricity and house
heating/cooling loss cost range is based on certain assumptions regarding
climate, your house size, and the cost of electricity and
fuel. Costs for cosmetic treatments to the house may
increase the typical installation costs.
INSTALLATION CHECK and FUTURE MAINTENANCE
test your home again after it is fixed to be sure that radon levels have been
reduced. Most soil suction radon reduction systems include a monitor that will
indicate whether the system is operating properly. In addition, it’s a good idea
to retest your home regularly or use an "Electronic Digital Detector" to be sure radon levels remain low.
Below is a list of
basic installation requirements that your contractor should meet when installing a radon reduction
system in your home. It is important to verify with your contractor that the radon mitigation
standards are properly met
to ensure that your radon reduction system will be effective:
systems must be clearly labeled. This will avoid
accidental changes to the
system which could disrupt its function.
The exhaust pipe(s) of soil suction systems must vent above the surface of the roof
and 10 feet or more above
the ground, and at least 10 feet away from windows, doors, or other openings that could allow
the radon to reenter the house (if the exhaust pipes do not vent at least 2 feet
above these openings).
The exhaust fan must
not be located in or below a livable area. For instance, it should be in an unoccupied attic of the
house or outside — not in a basement!
If installing an exhaust fan outside, the contractor must install a fan that meets local building codes for exterior
Electrical connections of all active radon reduction systems
must be installed according to local electrical
A warning device must be installed to alert you if an active system stops
working properly. Examples
of system failure warning devices are: a liquid gauge, a sound alarm, a light indicator, and a dial
(needle display) gauge. The warning device must
be placed where it can be seen or heard easily. Your contractor should
check that the warning
device works. Later on, if your monitor shows that the system is not
working properly, call a
contractor to have it checked.
post-mitigation radon test should be done within 30 days of system installation,
but no sooner than 24 hours
after your system is in operation with the fan on, if it has one. The contractor may perform a
post-mitigation test to check his work and the initial effectiveness of the system;
however, it is recommend that you also get an independent follow-up radon measurement.
Having an independent tester perform the test, or conducting the measurement
yourself, will eliminate any potential conflict of interest.
Make sure your contractor completely
explains your radon reduction system, demonstrates how it operates, and
explains how to maintain it. Ask for written operating and maintenance instructions
and copies of any warranties.
Similar to a
furnace or chimney, radon reduction systems need some occasional maintenance.
You should look at your warning device on a regular basis to make sure the
system is working correctly. Fans may last for five years or more (manufacturer
warranties tend not to exceed five years) and may then need to be repaired or
replaced. Remember, the fan should NEVER be turned off; it must run continuously
for the system to work correctly.
The filter in an
HRV requires periodic cleaning and should be changed twice a year. Also, the
vent that brings fresh air in from the outside needs to be inspected for leaves
and debris. The ventilator should be checked annually to make sure the air flow
remains properly balanced. HRVs used for radon control should run all the