Radon Mitigation Systems
Radon mitigation is any process or system used to reduce radon concentrations in buildings. The goal of the radon mitigation system is to reduce the indoor radon level as low as reasonably achievable. All systems should reduce radon below the EPA action level of 4 pCi/L (picocuries of radon per liter of air). A quality radon mitigation system may reduce year-round levels to below 2 pCi/L.
A home's foundation type helps determine the radon mitigation system that will work best. A radon mitigation professional should determine the type of mitigation system to install and may conduct some diagnostic testing. Radon mitigation systems use a fan to continuously pull air from the soil and exhaust it outdoors through a pipe. The pipe can either run inside or outside the home and discharges outside, away from the windows and openings. In addition, cracks and openings in the foundation are sealed. Sealing limits the flow of radon and makes the radon mitigation system more efficient.
The PBS series "Ask this Old House" visited a home in Minneapolis to install a radon mitigation system. The episode covers how radon systems are properly designed and installed. This video gives the viewer a good sense of what to expect from a radon mitigation professional and radon mitigation system.
Three of the most common types of radon mitigation systems
- Sub-slab suction - Pulls radon directly beneath the home's foundation and vents it outside.
- Drain tile suction - Pipe penetrates into the drain tile and vents the soil gases outside. Covers are placed on the sump baskets.
- Sub-membrane - Used in crawl spaces, a plastic sheet covers exposed dirt on the floor, extends up onto the wall and is sealed. A radon pipe penetrates the plastic sheeting, pulls the soil gas from the crawl space, and vents it outside.
Radon mitigation system components
Radon fan is located in an unconditioned space, like an attic or outside, to prevent radon leaking back into the home. The fan cannot be in or below a livable space. The fan is plugged into an electrical junction box or hard wired.
Radon system tag is placed on the system by a licensed radon professional once the system is complete.
Two Fan monitors (an active notification monitor and a U-tube monitor) are devices installed to indicate the fan is working.
Radon pipe vent discharge must be at least 10 feet above ground, 10 feet away from windows, openings, doors, openings to adjacent buildings (if the exhaust pipe(s) does not vent at least 2 feet above these openings), and above the edge of the roof.
A printable version of the diagram can be found at Radon Mitigation System Diagram (PDF)
Cost of a radon mitigation system
The cost can depend on many factors including the type of radon system to be installed and how your home was built. In general, costs can range from $1,500 to $2,500. Financial assistance may be available to help pay for a radon mitigation system and depends on household income, geographic location, and funding availability.
Finding a professional to install a radon mitigation system
Minnesota requires radon mitigation professionals to be licensed. Find a Radon Mitigation Professional.
10 step guide to the radon mitigation process
- Radon test reveals the home has a radon problem.
- Contact licensed radon mitigation professionals to request bids.
- Professional does a walk-through of the home to identify the mitigation system to install.
- Review key questions with professional, and request a proposal.
- Review bids and select a professional.
- Professional may perform diagnostic testing to ensure the proper fan size and correct installation.
- Professional seals cracks and openings in the basement.
- Professional installs the radon mitigation system.
- Professional provides a full explanation of how the system operates to the homeowner.
- Retest the home to ensure the system has reduced radon levels.
Other key features of a system
- Radon reduction systems must be clearly labeled. This will avoid accidental changes to the system which could disrupt its function.
- A post-mitigation radon test should be done no sooner than 24 hours after your system is in operation with the fan on and last at least 48 hours.
- Attached written operating and maintenance instructions and copies of any warranties.