How Radon is Mitigated
We guarantee your radon level will be reduced to below
4pCi/L according to EPA standards.
Mitigation Systems
There are two most common types of mitigation systems. They are sub-slab
depressurization and sub-membrane depressurization systems. A
sub-slab system pulls the air from underneath the concrete floor in
the basement area. A hole is made through the floor, along an
outside wall preferably, and then a ventilation pipe is sealed into
the hole and routed to the exterior. A fan is installed in the pipe
to create a constant vacuum to draw the air/gas from under the slab.
A sub-membrane system is used in crawl spaces and under sub-floors.
A plastic membrane is used to seal the soil area and the vent system
then draws the air/gas out from under the plastic membrane.
Depending on the type of system and the quantity of materials needed
the cost can vary. The most basic of sub-slab depressurization
systems begin at $1200.
With either system,
only the highest quality materials are used
during the installation, assuring many years of worry free service.
Our lead installation tech has installed hundreds of systems and is
experienced in seeking out options as to where, and how, to install
and rout a system for optimum performance as well as being
aesthetically pleasing.
How Radon is Mitigated
You will never find a level of ZERO in any radon test. Even outdoor
air typically has 0.2 to 0.7 pCi/l of radon. However, when a home or
building is found to have radon levels that can be considered
hazardous, action can be taken to reduce it to acceptable levels.
There are several methods that can be used to permanently correct
this problem.
The most common approach is what is known as “Active Soil
Depressurization” or “ASD.” This method involves drawing the soil
gasses (including radon) from the soils that are directly adjacent
to the structure. In order for this method to be effective, a sealed
barrier between the home and the soil must be available to divert
the radon out-gassing away from the home.
In a home with a basement, the concrete slab acts as a barrier
between the home and the soil. In this case, a PVC pipe penetrates
the slab through an existing opening (such as a sealed-off sump
basin) or through a hole in the slab that is created with a coring
drill. There is usually a small void between the slab and the soil
which allows soil gasses (including radon) to collect, become
pressurized, and eventually drawn into the home. Once the radon pipe
is inserted into this void area and a suction fan is installed, the
radon is drawn into the system and released outdoors. This method is
known as sub-slab depressurization and is the most common type of
ASD systems.
Other forms of ASD work in a similar manner. For example, homes
without basements may use the hollow cavities within the
block-wall(s) or drain-tile pipes(s) to collect the radon gas and
draw it outside before it can enter the home. Homes with exposed
dirt or gravel crawl space areas can be mitigated by the use of a
plastic membrane installed over the exposed area. Then the pipe and
fan system draw the air (and radon) out from under the plastic
membrane and release it outdoors.
99% of all radon problems can be corrected by use of Active Soil
Depressurization. This is the preferred method of radon mitigation
since it primarily involves extracting air from beneath the home’s
foundation (which is the air from soil, or “dirty” air.) Since these
systems are designed to avoid the loss of “conditioned” (heated or
cooled) air from the home, they have very little impact on the
efficiency of the home. There are other advantages to having an ASD
system in your home. The systems draw moisture out from under the
home before it can enter (like a pre-emptive dehumidifier), and have
also been shown to reduce mold spore growth, and eliminate airborne
bacteria (which develops in the moist soil beneath the home.
Other methods of reducing radon usually involve exchanging the
inside air with outside air. This is known as “dilution.” Although
dilution can be an effective way of reducing a home’s radon level,
it is not practical because of the cost involved in heating and
cooling inside air. Imagine the impact on your heating bill if you
left windows open in the wintertime.
The most important thing to realize is that a radon problem can be
corrected in any home. A home with a radon mitigation system will
consistently have radon levels well below the average American home
regardless of how high the radon levels were prior to mitigation.
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 during the initial phase of the
installation to help develop the best radon reduction system for
your home. For instance, your contractor can use chemical smoke 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. A
contractor may have concerns about backdrafting of combustion
appliances when considering radon mitigation options, and may
recommend that the homeowner have the appliance(s) checked by a
qualified inspector.
Another type of diagnostic test is a "soil communication test."
This test uses a vacuum cleaner and chemical smoke 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
chemical smoke 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.
House Foundation Types
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.