Building Radon Out: A Guide to Radon-Resistant New Home Construction

You’re building a new home – this is the perfect opportunity to prevent radon risks right from the start through smart construction. Radon-resistant new home design stops this radioactive gas from ever accumulating to hazardous levels in your household air. Use these essential radon-resistant features and techniques recommended by the EPA when building your new dream home.

The Health Risks of Radon Exposure

Radon is an odorless, radioactive gas formed from natural underground uranium decay. It seeps into homes through small foundation cracks and openings. As radon accumulates in indoor air, it further decays into radioactive particles that lodge in our lungs when inhaled, damaging cells and eventually causing lung cancer.

Radon is the second leading cause of lung cancer deaths in the U.S. after smoking. About 21,000 lung cancer deaths occur per year in the U.S. due to radon according to EPA estimates. The only way to protect your family from radon is through preventative measures like these radon-resistant construction techniques.

Radon-Resistant Basics

The goal of radon-resistant new home design is preventing radon gas from entering the home from surrounding soils. This is achieved through:

  • Installing a vapor barrier under concrete slabs
  • Sealing and caulking foundation walls and all openings
  • Adding a layer of gravel beneath slabs and plastic sheeting
  • Proper placement and slope of perforated pipes in the ground
  • Finishing crawl spaces according to radon-resistant standards

When built right from the start using these protective measures, radon mitigation systems can often be avoided in new homes.

Required Radon-Resistant Techniques

At a minimum, all new homes should include these radon-resistant installation standards:

  • Gravel Layer – 4 inches of clean gravel placed under concrete slab foundations. A 2-inch upper layer of gravel is compacted to make a more uniform base for slabs. Gravel extends 12 inches horizontally from the edge of the slab.
  • Plastic Sheeting – Minimum 6 mil polyethylene plastic sheeting laid above gravel layer to serve as gas/moisture barrier before pouring concrete foundation. Sheeting seams are overlapped 12 inches and taped.
  • Sealing – All foundation wall, floor, joint, and opening interfaces are caulked and sealed to limit potential radon entry routes. Quality sealants like urethane or silicone are used.
  • Vent Pipe – A 3- or 4-inch PVC vent pipe run horizontally through foundation connected to a vertical riser to roof serves as route for radon dilution.

Optional Enhanced Radon-Resistant Features

Other recommended radon-resistant techniques that further reduce risks include:

  • Adding a vapor barrier above gravel layer below slabs
  • Using solid concrete block walls instead of brick or stone
  • Installing a drain tile system connected to sump pump
  • Increasing gravel layer depth to 6 inches
  • Adding concrete floor sealant coating
  • Using adhesive-backed sheeting attachment
  • Having an electrical box linked to vent pipes for potential powered fan
  • Using passive sub slab ventilation by linked interior and exterior pipes

Radon-Resistant Standards for Crawl Spaces

The EPA has separate radon-resistant protocols for homes built over crawl spaces:

  • Crawlspace vents to exterior around entire space perimeter
  • 6 mil polyethylene sheeting on crawlspace floor with seams overlapped 12 inches
  • Sheeting runs up crawlspace walls at least 6 inches and is sealed to sill plates
  • Sealing all cracks and openings in foundation walls and joints
  • A 3- or 4-inch vent pipe runs from crawlspace through roof

Plan Ahead for Radon-Free Homes

The small investments made in radon-resistant techniques during new home construction can prevent dangerous radon exposure and save thousands on future mitigation costs. Follow these best practices for your new build. Consult county inspectors to ensure proper materials and radon-resistant installations that align with local codes.

Scroll to Top