Radon resistant new construction

Radon-Resistant New Construction

When new homes are built, they can be constructed with radon resistant features. Adding these features during the construction process is much less expensive than adding radon-resistant features later on. According to the United States Environmental Protection Agency, the cost of Radon Resistant New Construction is usually between $250 and $750. The cost could be less than $250 if the builder already uses some of the same techniques used for moisture control. The cost of installing a radon mitigation system post construction is between $1200 and $2000.

Homeowners who have radon resistant features in their house should still test their home for radon every 2 years. Test kits can be purchased at Linn County Public Health or at local hardware stores.

Finding a Builder Who Uses Radon-Resistant Techniques

All homes and additions to existing homes in unincorporated Linn County must be built using radon-resistant techniques. For many, finding a builder can be difficult, but finding one who uses radon-resistant techniques can be easy. The EPA provides a Directory of Builders who are using this technique which can be found by clickinghere. Once you have chosen your builder, use this EPA checklist to be sure that Radon-Resistant features have been installed in your home.

How does Radon Resistant New Construction work?

How do I know if my fan is working?

If you have an active radon system typically you will have what is called a U-tube manometer that measures fan operation. The level of liquid in the manometer should not be at an equal level on both sides. If the level is uneven, this means that the fan is operating correctly.

Courtesy: VSI

Linn County Public Health Radon Study

Linn County Public Health (LCPH) conducted a radon evaluation project in 2013 to determine radon levels in new construction homes. LCPH obtained a list of building permits issued between 2008 and 2012 in unincorporated Linn County, Cedar Rapids, and Marion. A letter was sent to the addresses for participation. The evaluation project was under the supervision of staff who has received formalized training on radon mitigation and measurement. LCPH staff placed two short-term charcoal radon test kits on the lowest lived-in level of the home and according to testing instructions. Two kits were placed within four inches of each other as a quality control technique; the relative percent difference between the test kits was calculated to determine the validity of the kits and to quickly verify radon levels.

During the evaluation LCPH assessed the average radon levels, the type of radon system, and condition of the sump pit. The gravel base, vapor barrier, cracks and crevices in the concrete foundation were not assessed. All of these factors can influence radon levels within the home.

Evaluation Results

LCPH evaluated whether the homes had an active mitigation system, a passive system, or no radon reduction system (Figure 1). The visual assessment was conducted with the understanding that LCPH could only assess the conditions that existed at that time. Radon systems were assigned to one of the three following categories based on function:

1. Active Radon System: 3” or 4” PVC pipe that extends from below the building foundation to the exterior of the home with a powered vent fan actively pulling air below the foundation.

2. Passive Radon System: 3” or 4” PVC pipe that extends from below the building foundation to the exterior of the home, but which does not have a powered vent fan.

3. No Radon System: No evidence of a functional venting system to remove radon gas.

LCPH evaluated only what was visible in the basement or slab-on-grade and from the outside of the home, but did not observe the entire system or if the fan was operating. The determination of passive or active system was made on the observation of a pipe in the basement, a pipe coming out of the roof, and whether a manometer (present in active systems) was observed.

LCPH also assessed the condition of the sump pit. Radon enters your home through cracks and crevices, and unsealed sump pits provide a direct pathway for soil gases to enter the home and build up. Of the 97 homes with complete data, more than 50% had an unsealed sump pit. Homes with a sealed sump pit and no sump pit were considered functionally the same, and therefore lumped into one category (Figure 2).

Sealed Sump Pit: Described as no visible gaps, cracks, or crevices that will allow air flow from below the building foundation into the living environment. Gaps, cracks, and crevices are hermetically sealed with gaskets, silicone caulking, or equivalent.

Unsealed Sump Pit: Allows air to flow into the living environment from below the building foundation. An unsealed sump pit may be missing gaskets or a lid. May see PVC pipe terminate outside of the lid.

Of these data, LCPH compared the average radon levels by the type of radon system and sump pit. Of the 97 homes included in this evaluation, 96 were included in Figure 3. One home was excluded because radon screen levels were significantly higher (22.2 pCi/L) compared to other homes range of 0.3 to 13.2 pCi/L.

(Sealed sump lid example)

Summary of Figure 3

No Radon Removal System: 48% of homes without radon removal systems had average radon levels above the EPA action level of 4.0 pCi/L. However, average radon levels were slightly lower in homes with a sealed sump pit or no sump pit.

Passive Radon System: Homes with a passive radon system and either a sealed sump pit or no sump pit had lower average radon levels compared to those with unsealed sump pits. Average radon levels in homes with a passive radon system and an unsealed sump pit were near the EPA action level. However, 24% of homes with a passive radon system had radon levels above the EPA action level of 4.0 pCi/L.

Active Radon System: Homes with an active radon removal system and sealed sump pit had average radon levels closer to expected ambient air radon levels and none were above the EPA action level (4.00pCi/L).

Radon Evaluation Conclusions:

• Homes with an unsealed sump pit are more likely to have higher radon levels than homes with a sealed sump pit.

• Homes without a radon removal system are more likely to have higher radon levels than homes with a passive or active radon system.

• The majority of homes in Linn County do not have radon removal systems.

• More homes are likely to have an unsealed sump pit instead of a sealed or no sump pit.

Additional Information can be found by clicking on the links below:






Are you a contractor looking to get certified in Radon Resistant New Construction? Click on the links below for more information about techniques and certification.