Radon Mitigation Systems

Radon mitigation is any process or system used to reduce radon concentrations in the breathing zones of occupied buildings. The goal of a radon mitigation system is to reduce the indoor radon levels to below the EPA action level of 4 pCi/L. A quality radon reduction (mitigation) system is often able to reduce the annual average radon level to below 2 pCi/L. In general, costs can range from approximately $800-$2500, with the average reduction system costing approximately $1500.

Financial Assistance for Installing Radon Mitigation Systems

The Minnesota Housing Finance Agency (MHFA) offers a financing program, The Fix-Up Fund, for homeowners looking to make improvements on the their homes. Fix-Up Fund financing can make radon mitigation more affordable for eligible homeowners through low-interest fixed rate loans. If a mitigation system does not meet the minimum loan requirement, it can easily be paired with other home improvements to further increase the affordability of your projects. For more information visit the MHFA fix-up fund website.

Foundations

Diagram of multiple foundation types

Any home can have a radon problem, no matter what type of foundation it has.

  • Basement: provides a large surface area in contact with soil material. Radon can enter through cracks in the concrete, or through floor-to-wall joints or control joints. Since many Minnesota homes use their basements as living space, exposure to radon can be further increased. But radon can enter a home regardless of whether or not there is a basement.
  • Slab-On-Grade: Slabs built on grade can have many openings that allow radon to enter, just as in a basement.
  • Crawl Space: Homes with crawl spaces can also have elevated radon levels. The vacuum effect can draw radon gas from a crawl space into the home.
  • Manufactured Homes: Unless these buildings are placed on supports without skirting around them, interior air pressure vacuums can cause radon to enter manufactured homes, as well.

Suction System

The are four types of soil suction systems: sub-slab, drain tile, sub-membrane and block wall.

diagram of sub slab radon mitigation system
  • Active sub-slab suction: (also called the sub-slab depressurization, or SSD) is the most common and usually the most reliable system because it draws radon-filled air from beneath the house and vents it outside.
  • Passive sub-slab suction: is the same as active sub-slab suction, except not as effective. It relies on air currents instead of a fan to draw radon up from below the house.
  • Drain tile suction system: caps are placed on the sump pump baskets. The pump continues to drain unwanted water.
  • Block wall suction: systems are used in homes with hollow block foundations by using a system similar to the sub-slab suction, where radon is removed from the wall by depressurization.

10 Step Process

  1. Homeowner's radon test reveals the home has a radon problem.
  2. Homeowner contacts certified mitigators to request bids.
  3. Contractor does a walk-through of the home to identify problems then outlines the mitigation system they recommend.
  4. Homeowner reviews key questions with each contractor requesting a proposal bid and references.
  5. Homeowner evaluates and compares contractor recommendations, bids and contracts, selecting the contractor and scheduling the work.
  6. Contractor may perform diagnostic testing to ensure proper size and installation methods are applied.
  7. Contractor seals required areas, e.g., large cracks, crawl spaces, sumps, etc.
  8. Contractor installs the mitigation system, i.e., suction pit or ventilation, pipe routing, etc. Electrical hook-up completed by licensed electrician, not a licensed contractor.
  9. Contractor provides full explanation of system's operation to homeowner.
  10. Homeowner or contractor test the home to ensure the system is reducing radon to the desired level.

Other methods to Reduce radon levels

Other radon reduction techniques may be considered to reduce the radon gas levels that are circulating within the home. Many of these methods are used only as temporary measures, or in combination with other measures, like the ventilation or suction system.

  • Ventilation: can sometimes lower indoor radon levels in crawl spaces by reducing the home's suction on the soil and by diluting the radon beneath the house. Passive ventilation is achieved by opening or installing vents. Active ventilation uses a fan to blow air through the crawl space. To be effective, ventilation is often used with sub-membrane depressurization, which covers the dirt of the crawl space floor with a plastic sheet. A pipe then draws the radon air from under the sheet to the outside.
  • Sealing: cracks and openings in the foundation is a basic step in radon mitigation. Sealing will limit the flow of radon, making other mitigation techniques more efficient. This is a temporary measure because normal settling of a home opens new entry routes and reopens old ones.
  • Pressurization: uses a fan to blow air into the lower level of the home, creating enough pressure to prevent radon entering. To maintain enough pressure, doors and windows at the lowest level must not be left open.
  • Heat recovery ventilator (HRV): (also called an air-to-air heat exchanger) is used to increase ventilation in all or part of a home. The HRV introduces outdoor air by using the heated or cooled exhausted air to warm or cool the incoming air.
Updated Wednesday, 01-Aug-2012 09:07:20 CDT