EPA-Home Buyers & Sellers Guide to Radon-2018
CDPHE: Colorado Radon Fact Sheet
January is Radon Awareness Month. When it comes to your real estate transaction, both Sellers & Buyers need to be aware of disclosure laws, the risks of radon & remediation options. Radon is a naturally occurring radioactive gas that comes from the breakdown or uranium in the soil. Radon odorless, colorless, tasteless &can enter your home from the soil beneath it.
Breathing radon gas for prolonged periods of time can present a significant health risk for you and your family. High radon levels have been found in all 50 states and in all parts of Colorado. Radon is the leading cause of lung cancer among non-smokers in the United States and is responsible for approximately 500 lung cancer deaths annually in Colorado.
The U.S. EPA and the U.S. Geological Survey have raised the radon potential in Colorado and have established Colorado as a Zone 1 state. Zone 1 states have the highest risk for elevated radon and should consider radon mitigation of the upmost importance. About half of Colorado homes have radon levels higher than the U.S. Environmental Protection Agency recommended action level of 4 picocuries per liter (pCi/L):
As a home buyer, testing for radon is recommended during the Inspection Phase of a purchase transaction. Radon can be detected with a simple test, typically performed by your general home inspector. In addition, the Environmental Conditions portion of the Colorado Seller’s Property Disclosure Form specifically lists radon as a hazard that must be disclosed by a Seller if it is known by the seller to exist or ever have existed. This is true even if previous test results were less than 4.0 pCi/L.
- Sellers should provide copies of any test results.
- Existence of a radon mitigation system must be disclosed. (It is presumed that radon existed previously, and that if the system were to fail, the radon level would return to its original level.)
Radon mitigation (also known as remediation or abatement) is a process to reduce or remove radon gas levels from a building. There are multiple radon mitigation techniques. Proper and high-quality radon mitigation accomplishes two things:
- It reduces the concentration of radon gas in your home, venting it safely outside the structure.
- Correctly installed radon mitigation systems remove the radon gas from under the foundation of a structure before it can come in.
How do Radon Systems Work?
Some radon reduction systems can reduce radon levels in your home by up to 99 percent. Most homes can be fixed for about the same cost as other common home repairs. Your costs may vary depending on the size and design of your home, the radon levels present and which radon reduction methods are needed. Hundreds of thousands of people have successfully reduced radon levels in their homes.
While the exact type of radon mitigation system you’ll need may depend on the structure of your home, certain techniques are used for almost every type of radon mitigation procedure. These include both passive and active radon systems: Sub-slab depressurization systems; Sub-membrane depressurization (SMD) for dirt crawl spaces; and in some rare occasions, air exchangers. Sealing of large cracks and openings in basement slabs are also part of most radon mitigation procedures. These systems are designed to be unobtrusive and interfere as little as possible with the decor of your home.
The most common method of radon mitigation is a “sub-slab depressurization” (SSD) system, which uses a fan and PVC pipe to draw air from below the basement floor or slab on grade and then vent it harmlessly above the roof, where it dissipates very quickly.
Sub-Membrane Depressurization for Crawl Spaces
If your home has an exposed dirt crawlspace, the dirt will normally be encapsulated with a special plastic membrane that is sealed to the perimeter foundation walls of the crawl space. The membrane is also sealed around support columns and any plumbing stacks that go into the dirt floor of the crawl space. A “collection pipe” (a length of perforated PVC or ADS pipe) is sealed under the membrane and “teed” into the piping connected to the fan and vent stack. The system draws air from under the sealed membrane and removes most of the moisture coming from the soil. This is also a popular method for dehumidifying damp, musty crawl spaces and for mold mitigation.
The sealing of holes, cracks, and sump covers near the suction point is done as part of the mitigation process, to prevent the loss of vacuum pressure near the vent pipe.
This sealing is only part of a broader radon mitigation process. Painting or caulking over cracks and openings in an attempt to “do it yourself” will not significantly reduce radon levels.
Some homes have unusual conditions under the floor or have large crawl spaces that are inaccessible or impossible to effectively encapsulate. In these cases, an air-to-air heat exchanger (also known as a Heat Recovery or Energy Recovery Ventilator, HRV or ERV) can be used to effectively reduce radon levels in structures that have radon levels less than 12 pCi/L.
An HRV is a machine that exchanges the air from inside and outside the structure, via two sets of flexible ducts: one blowing air into the house and one blowing air out of the house. The fresh air coming into the house is tempered slightly so as not to cause a substantial energy penalty. The HRV/ERV reduces the radon through the process of dilution by exhausting the stale indoor air out, while bringing in fresh outdoor air that averages 0.4 pCi/L.
Radon Vent Fans
Radon vent fans are specialized devices — sealed units that will not leak or allow the radon flowing through them to escape. There are certain requirements that must be followed for fan installation:
- Radon vent fans need to be fitted to account for the pressure difference and air-flow dynamics needed to reach radon reduction objectives. The type of fan is determined by the sub-slab conditions, the size of the slab and the extent of the radon problem.
- For depressurization systems, vent fans cannot be installed in basements, or crawl spaces. National ASTM radon mitigation standards do not permit the fans to be located in the conditioned envelope of the house.
- Radon fans are permitted in unfinished attics, garages (not below conditioned spaces) or on the outside of the building.
- Finally, radon systems need to be screened at the exhaust discharge point (end of the vent stack) to prevent animals or large debris from going into the pipe and fan.
Why Call a Radon Mitigation Expert?
Radon mitigation calls for professional expertise. Do-it-yourself techniques will not significantly reduce radon levels in your home. Shoddy or cheap work may fail to reduce radon levels, which is why it’s important to work with experienced professionals who are both licensed and insured, and who have the experience required to get the work done quickly and to the highest standards. Your Realtor will be able to refer you to radon remediation companies for a professional estimate once you have radon test results in hand.