Radon Measurement Services
There are several methods 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 that prevent the entry of radon. Soil
suction,for example, prevents radon from entering your home by drawing the radon from below the home and venting it through a pipe,
or pipes, to the air above the home where it is quickly diluted.
Any information that you may have about the construction of your home
could help your contractor choose the best system. Your contractor will perform a visual inspection of your home and design a system
that considers specific features of your home. If this inspection fails to provide enough information, the contractor may 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 appliances 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
Whether diagnostic tests are needed is decided by details specific to your home, such as the foundation design, what
kind of material is under your home, and by the contractor’s experience with similar homes and similar radon test results.
Your home type will affect the kind of radon reduction system that will work best. Homes 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 homes have more than one foundation design feature. Florida homes typically are built with a slab-on-grade construction
or in some older homes crawlspace foundation.
In homes that have a slab-on-grade foundation,
radon is usually reduced by subslab suction. Active subslab suction — also called subslab depressurization —is the most common and
usually the most reliable radon reduction method. One or more 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 home. 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 contractor usually gets this information from visual inspection, from diagnostic
tests or from experience. A radon vent fan connected to the suction pipes draws the radon gas from below the home and releases it
into the outdoor air while simultaneously creating a negative pressure or vacuum beneath the slab. Common fan locations include unconditioned
home and garage spaces, including attics and the exterior of the home.
Passive subslab suction is the same as active subslab
suction except it relies on natural pressure differentials and air currents instead of a fan to draw radon up from below the home.
Passive subslab suction is usually associated with radon-resistant features installed in newly constructed homes. Passive subslab
suctionis generally not as effective in reducing high radon levels as active subslab suction.
An effective method
to reduce radon levels in crawlspace homes 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 submembrane suction,
and when properly applied is the most effective way to reduce radon levels in crawlspace homes.Another 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 submembrane suction and requires special attention to combustion appliance backdrafting and sealing the crawlspace
from other portions of the home. It also may result in increased energy costs due to loss of conditioned air from the home.
cases, radon levels can be lowered by ventilating the crawlspace passively, or actively, with 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 home. Passive
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.
Similar to a furnace or chimney, radon reduction
systems need occasional maintenance. If you have a fan powered (or active) system, you should look at your warning device, usually
a manometer, 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. Replacing a fan will cost around $350 to
$650, including parts and labor. It is a good idea to retest your home at least every two years to be sure radon levels remain low.
the fan should NEVER be turned off; it must run continuously for the system to work correctly.