Mitigation Methods
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 which 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 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 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 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 your home.
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.
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 which 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 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 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 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 your home.
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.
Foundation Types
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 crawl space, a shallow unfinished space under the first floor.
Some homes have more than one foundation design feature. For instance, it is common to have a basement under part of the home and to have a slab-on-grade or crawlspace under the rest of the home. In these situations a combination of radon reduction techniques may be needed to reduce radon levels to below 4 pCi/L.
The EPA recommends the following techniques as the most effective methods for reducing radon gas:
For more information on Radon Mitigation Methods, please visit the following link: Radon Reduction Techniques
Some homes have more than one foundation design feature. For instance, it is common to have a basement under part of the home and to have a slab-on-grade or crawlspace under the rest of the home. In these situations a combination of radon reduction techniques may be needed to reduce radon levels to below 4 pCi/L.
The EPA recommends the following techniques as the most effective methods for reducing radon gas:
- Sub Slab Depressurization - Inside Routing
- Sub Slab Depressurization - Exterior Routing
- Drain Tile Depressurization - Drain to Daylight
- Drain Tile Depressurization - Internal
For more information on Radon Mitigation Methods, please visit the following link: Radon Reduction Techniques
Crawl Spaces
Crawl Spaces in a building or house can be an issue to contend with when planning radon mitigation. Some crawl spaces are cemented over during construction or even after. Others are left open, exposing gravel and sand fill, or simply the natural occurring dirt mix found during excavation. These open crawl spaces are the ones that can be problematic in the end result to radon mitigations. Crawl spaces typically fall outside of the main house or building drain-tile system, and footing area. They have their own footing area, and hence, separate earth gas penetration that "can" cause a potential separate high radon area from the basement area.
At A1RS, we feel that pre-testing the basement and main area of the house is important… as well as testing the open crawl space(s) and areas over these crawl spaces. This “baselines” all data before any mitigation work is done, and allows post-mitigation testing comparisons to be made. As typical basement mitigation pulls on sub-slab areas typically 3'-6' deeper than standard crawl space areas, about 80% of “typical” sub-slab depressurization style mitigations cure the basement… and crawl space areas of high radon levels. The other 20% still pose high radon entrance points, and are only cured my covering the open earth air-tight, and running a lateral from the main mitigation piping to the crawl space and through the air-tight membrane.
The best way to quote radon mitigations containing open earth areas is to provide step-by-step mitigation pricing relative to testing and results. Since 80% of open earth areas don’t need to be covered and mitigated to get all livable spaces in the house or building to safe levels, it shouldn’t be necessary to cover and mitigate these areas until they prove to still be high in radon after initial post-mitigation testing. It should be noted that there are no EPA/ASTM protocols directed at the “need” to cover open-earth crawl spaces. There are protocols on how to cover and mitigate crawl spaces if they prove to remain high after the initial sub-slab mitigation.
14.5.7
In combination basement/crawlspace foundations, where the crawlspace has been confirmed as a source of radon entry, access doors and other openings between the basement and the adjacent crawlspace shall be closed and sealed. Access doors required by code shall be fitted with air tight gaskets and a means of positive closure, but shall not be permanently sealed. In cases where both the basement and the adjacent crawlspace areas are being mitigated with active SSD and SMD systems, sealing of the openings between those areas is not required. Pulled from the EPA Radon mitigation standards (RMS) manual
Crawl Spaces in a building or house can be an issue to contend with when planning radon mitigation. Some crawl spaces are cemented over during construction or even after. Others are left open, exposing gravel and sand fill, or simply the natural occurring dirt mix found during excavation. These open crawl spaces are the ones that can be problematic in the end result to radon mitigations. Crawl spaces typically fall outside of the main house or building drain-tile system, and footing area. They have their own footing area, and hence, separate earth gas penetration that "can" cause a potential separate high radon area from the basement area.
At A1RS, we feel that pre-testing the basement and main area of the house is important… as well as testing the open crawl space(s) and areas over these crawl spaces. This “baselines” all data before any mitigation work is done, and allows post-mitigation testing comparisons to be made. As typical basement mitigation pulls on sub-slab areas typically 3'-6' deeper than standard crawl space areas, about 80% of “typical” sub-slab depressurization style mitigations cure the basement… and crawl space areas of high radon levels. The other 20% still pose high radon entrance points, and are only cured my covering the open earth air-tight, and running a lateral from the main mitigation piping to the crawl space and through the air-tight membrane.
The best way to quote radon mitigations containing open earth areas is to provide step-by-step mitigation pricing relative to testing and results. Since 80% of open earth areas don’t need to be covered and mitigated to get all livable spaces in the house or building to safe levels, it shouldn’t be necessary to cover and mitigate these areas until they prove to still be high in radon after initial post-mitigation testing. It should be noted that there are no EPA/ASTM protocols directed at the “need” to cover open-earth crawl spaces. There are protocols on how to cover and mitigate crawl spaces if they prove to remain high after the initial sub-slab mitigation.
14.5.7
In combination basement/crawlspace foundations, where the crawlspace has been confirmed as a source of radon entry, access doors and other openings between the basement and the adjacent crawlspace shall be closed and sealed. Access doors required by code shall be fitted with air tight gaskets and a means of positive closure, but shall not be permanently sealed. In cases where both the basement and the adjacent crawlspace areas are being mitigated with active SSD and SMD systems, sealing of the openings between those areas is not required. Pulled from the EPA Radon mitigation standards (RMS) manual
EPA Moisture Study and Radon Mitigation Systems
For years, those involved with radon mitigation in buildings have reported that operation of
active soil depressurization (ASD) radon control systems appears to reduce moisture levels in the
basements of some houses (Turk and Harrison 1987; Brodhead 1996). These systems inhibit
advective radon entry by reversing the air pressure gradient between the soil and house
substructure. Reductions in musty and moldy odors, drying and shrinkage of materials in the
basement and less dampness in the basement have all been reported.
The development and exacerbation of asthma, along with other respiratory ailments, has been
related to damp indoor environments and dampness-dependent exposures to fungi and house dust
mites (Fisk et al 2007; IOM 2000; IOM 2004; Mannino et al 1998). Mudarri and Fisk (2007)
estimate that approximately 21% of all asthma cases in the U.S are attributable to dampness and mold exposure in homes. Other studies have specifically shown an association between damp basements and respiratory health symptoms (Brunekreef et al 1989; Dales et al 1991; Spengler et al 1994), and respiratory symptoms in children with dampness in housing (Jaakola et al 1993; Williamson et al 1997). Because of this link between dampness in houses and respiratory problems, the ability to control indoor moisture as well as radon and other soil gas pollutants has important public health ramifications.
The U.S. EPA Environmental Protection Agency (U.S. EPA) Indoor Environments Division
conducted a literature review, but found little, relevant, published information on systematic
studies of ASD-caused moisture changes in buildings. Although there can be many sources of
dampness in basements, it has been speculated that ASD systems interfere with air movement
that can carry moisture into basements (and other substructures), and with capillarity and
diffusion from the soil. Therefore, the U.S. EPA funded an exploratory project through Auburn
University to investigate this phenomenon and to determine if ASD may be a beneficial multipollutant control technique. This approach may also be more energy efficient than the use of dehumidifiers. Preliminary results on this project have been reported earlier (Turk et al 2007),
but expanded findings of this work are presented here: EPA Study
For years, those involved with radon mitigation in buildings have reported that operation of
active soil depressurization (ASD) radon control systems appears to reduce moisture levels in the
basements of some houses (Turk and Harrison 1987; Brodhead 1996). These systems inhibit
advective radon entry by reversing the air pressure gradient between the soil and house
substructure. Reductions in musty and moldy odors, drying and shrinkage of materials in the
basement and less dampness in the basement have all been reported.
The development and exacerbation of asthma, along with other respiratory ailments, has been
related to damp indoor environments and dampness-dependent exposures to fungi and house dust
mites (Fisk et al 2007; IOM 2000; IOM 2004; Mannino et al 1998). Mudarri and Fisk (2007)
estimate that approximately 21% of all asthma cases in the U.S are attributable to dampness and mold exposure in homes. Other studies have specifically shown an association between damp basements and respiratory health symptoms (Brunekreef et al 1989; Dales et al 1991; Spengler et al 1994), and respiratory symptoms in children with dampness in housing (Jaakola et al 1993; Williamson et al 1997). Because of this link between dampness in houses and respiratory problems, the ability to control indoor moisture as well as radon and other soil gas pollutants has important public health ramifications.
The U.S. EPA Environmental Protection Agency (U.S. EPA) Indoor Environments Division
conducted a literature review, but found little, relevant, published information on systematic
studies of ASD-caused moisture changes in buildings. Although there can be many sources of
dampness in basements, it has been speculated that ASD systems interfere with air movement
that can carry moisture into basements (and other substructures), and with capillarity and
diffusion from the soil. Therefore, the U.S. EPA funded an exploratory project through Auburn
University to investigate this phenomenon and to determine if ASD may be a beneficial multipollutant control technique. This approach may also be more energy efficient than the use of dehumidifiers. Preliminary results on this project have been reported earlier (Turk et al 2007),
but expanded findings of this work are presented here: EPA Study