to Look for in a Radon Reduction System
In selecting a radon reduction method for your home,
you and your contractor should consider several things,
including: how high your initial radon level is, the
costs of installation and system operation, your house
size and your foundation type.
and Operating Costs
For most homes, radon reduction measures are no more
expensive than having a new hot water heater installed
or having the house painted. The cost of a contractor
fixing a home generally ranges from $500 to $2500, depending
on the characteristics of the house and choice of radon
Most types of radon reduction systems
cause some loss of heated or air conditioned air, which
could increase your utility bills. How much your utility
bills will be affected depends on the climate you live
in, what kind of reduction system you select, and how
your house is built. Systems that use fans are more
effective in reducing radon levels; however, they will
increase your electric bill. The table below lists the
installation and average operating costs for different
radon reduction systems and describes the best use of
Radon Reduction System May Affect Your Home
In order to minimize the effect of installing a radon
reduction system in your house, ask your contractor
before any work starts how the system can be made to
blend with its surroundings. For instance: radon vent
pipes may be encased with materials that match the exterior
of your house, or the pipes may be routed up through
There are several methods that a contractor can use
to lower radon levels in your home. Some techniques
prevent radon from entering your home while others reduce
radon levels after it has entered. EPA generally recommends
methods which prevent the entry of radon. Soil suction,
for example, prevents radon from entering your home
by drawing the radon from below the house and venting
it through a pipe, or pipes, to the air above the house
where it is quickly diluted.
Any information that you may have
about the construction of your house could help your
contractor choose the best system. Your contractor will
perform a visual inspection of your house and design
a system that considers specific features of your house.
If this inspection fails to provide enough information,
the contractor will need to perform diagnostic tests
to help develop the best radon reduction system for
your home. For instance, your contractor can use a "smoke
gun" to find the source and direction of air movement.
A contractor can learn air flow sources and directions
by watching a small amount of smoke that he or she shot
into holes, drains, sumps, or along cracks. The sources
of air flow show possible radon routes.
Another type of diagnostic test is
a "soil communication test." This test uses
a vacuum cleaner and a smoke gun to determine how easily
air can move from one point to another under the foundation.
By inserting a vacuum cleaner hose in one small hole
and using a smoke gun in a second small hole, a contractor
can see if the smoke is pulled down into the second
hole by the force of the vacuum cleaner's suction. Watching
the smoke during a soil communication test helps a contractor
decide if certain radon reduction systems would work
well in your house.
Whether diagnostic tests are needed
is decided by details specific to your house, such as
the foundation design, what kind of material is under
your house, and by the contractor's experience with
similar houses and similar radon test results.
Your house type will affect the kind of radon reduction
system that will work best. Houses are generally categorized
according to their foundation design. For example: 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. For instance, it is common to have a basement
under part of the house and to have a slab-on-grade
or crawlspace under the rest of the house. In these
situations a combination of radon reduction techniques
may be needed to reduce radon levels to below 4 pCi/L.
Radon reduction systems can be grouped
by house foundation design. Find your type of foundation
design above and read about which radon reduction systems
may be best for your house.
and Slab-on-Grade Houses
In houses that have a basement or a slab-on-grade foundation,
radon is usually reduced by one of four types of soil
suction: subslab suction, drain tile suction, sump hole
suction, or block wall suction.
Active Subslab suction (also called
subslab depressurization) is the most common and usually
the most reliable radon reduction method. Suction pipes
are inserted through the floor slab into the crushed
rock or soil underneath. 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.
A contractor usually gets this information from visual
inspection, from diagnostic tests, and/or from experience.
Acting like a vacuum cleaner, a fan connected to the
pipes draws the radon gas from below the house and then
releases it into the outdoor air. Passive subslab suction
is the same as active subslab suction except it relies
on air currents instead of a fan to draw radon up from
below the house. Passive subslab suction is generally
not as effective in reducing high radon levels as active
Some houses have drain tiles to direct
water away from the foundation of the house. Suction
on these drain tiles is often effective in reducing
radon levels if the drain tiles form a complete loop
around the foundation.
One variation of subslab 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
Block wall suction can be used in
basement houses with hollow block foundation walls.
This method removes radon from the hollow spaces within
the basement's concrete block wall. It is often used
together with subslab suction.
In houses with crawlspaces, radon levels can sometimes
be lowered by ventilating the crawlspace passively (without
the use of a fan) or actively (with the use of a fan).
Crawlspace ventilation lowers indoor radon levels both
by reducing the home's suction on the soil and by diluting
the radon beneath the house. Natural ventilation in
a crawlspace is achieved by opening vents, or installing
additional vents. Active ventilation uses a fan to blow
air through the crawlspace instead of relying on natural
air circulation. In colder climates, for either natural
or active crawlspace ventilation, water pipes in the
crawlspace need to be insulated against the cold.
Another effective method to reduce
radon levels in crawl space houses involves covering
the earth floor with a heavy 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 depressurization.
Types of Radon Reduction Methods
Other radon reduction techniques that can be used in
any type of house include: sealing, house pressurization,
natural ventilation, and heat recovery ventilation.
Most of these methods are considered to be either temporary
measures, or only partial solutions to be used in combination
with other measures.
Sealing cracks and other openings
in the foundation is a basic part of most approaches
to radon reduction. Sealing does two things, it limits
the flow of radon into your home and it reduces the
loss of conditioned air, thereby making other radon
reduction techniques more effective and cost-efficient.
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.
House 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 not be left opened, except for normal entry and
Some natural 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 radon with
outside air and can result in reduced radon levels.
In addition, ventilating your house can help to lower
indoor radon levels by reducing the vacuum effect. Natural
ventilation in any type of house, (aside from ventilation
of a crawlspace), should normally be regarded as a temporary
radon reduction approach because of the following disadvantages:
loss of conditioned air and related discomfort, greatly
increased costs of conditioning additional outside air,
and security concerns.
A heat recovery ventilator (HRV),
also called an air-to-air heat exchanger, can be installed
to increase ventilation. An HRV will increase house
ventilation 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 also can improve air quality
in houses that have other indoor pollutants. There could
be significant increase in the heating and cooling costs
with an HRV, but not as great as ventilation without
heat recovery (see "Installation and Operating
Cost Table" below).
Your Radon Reduction System
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 (although manufacturer warranties tend
not to exceed three years) and may then need to be repaired
or replaced. Replacing a fan will cost around $250 including
parts and labor. By testing at least every two years,
you will confirm that your radon level is staying low
and that your fan is still performing well.
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. Replacement
filters for an HRV are easily changed and are priced
between $5 and $15. Ask your contractor where filters
can be purchased. 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
by a heating, ventilating, and air-conditioning professional
to make sure the air flow remains properly balanced.
HRVs used for radon control should run all the time.
Remodeling Your Home After
Radon Levels Have Been Lowered
If you decide to make major structural changes to your
home after you have had a radon reduction system installed
(such as converting an unfinished basement area into
living space), ask your radon contractor whether these
changes could void any warranties. After you remodel,
retest in the lowest lived-in area to make sure the
construction did not reduce the effectiveness of the
radon reduction system. If you are adding a new foundation
for an addition to your house, address the radon problem