Quality Assurance & Quality Control
Introduction to Radon Mitigation
Worker Health & Safety
2 of 3

RRNC Requirements

Labeling of Visible Pipes

  • All exposed and visible interior radon vent pipes must be conspicuously identified with at least one label on each floor and in accessible attics.
  • The label must read “Radon Reduction System”.

Combination Foundations

  • Combination basement/crawlspace or slab-on-grade/crawlspace foundations must have separate radon vent pipes installed in each type of foundation area or be connected with a continuous drain tile loop.
  • Vent pipes must connect to a single vent that must terminate:
  • at least 12 inches above the highest roof in a location
  • at least 2 feet above any window or other opening into the conditioned spaces of the building and
  • 10 feet from any window or other opening in adjoining or adjacent buildings.

Joints in Air Ducts & Plenums

  • Joints in air ducts and plenums in unconditioned spaces must meet the requirements of Section M1601 of the 2012 International Residential Code for One-and Two-Family Dwellings (copyrighted 2011 by the International Code Council, Inc.).
  • Thermal envelope air infiltration requirements must comply with the energy conservation provisions in Chapter 11 of the 2012 International Residential Code for One-and Two-Family Dwellings (copyrighted 2011 by the International Code Council, Inc.).
  • Fire stopping must be in conformance with the most recent general building code enacted by the city or meet the requirements contained in Section R302.11 of the 2012 International Residential Code for One-and Two-Family Dwellings (copyrighted 2011 by the International Code Council, Inc.).

Subfloor Preparation

  • A layer of gas-permeable material should be placed under all concrete slabs and other floor systems that directly contact the ground and are within the walls of the living spaces of the buildings, to facilitate future installation of a sub-slab depressurization system, if needed.
  • The gas permeable layer should consist of one of the following:
  • A uniform layer of clean aggregate, a minimum of 4 inches thick.
  • The aggregate should consist of material that will pass through a 2-inch sieve and be retained by a ¼ inch sieve.
  • A uniform layer of sand (native or fill), a minimum of 4 inches thick, overlain by a layer or strips of geo-textile drainage matting designed to allow the lateral flow of soil gases.
  • Other materials, systems or floor designs with demonstrated capability to permit depressurization across the entire subfloor area.

Blocking Potential Entry Routes – Drains, Floor Openings, etc.

  • Floor openings around bathtubs, showers, water closets, pipes, wires or other objects that penetrate concrete slabs or other floor assemblies should be filled with a polyurethane caulk or equivalent sealant applied in accordance with the manufacturer’s recommendations.
  • Condensate drains should be trapped or routed through non-perforated pipe to daylight.
  • All concrete control joints, isolation joints, construction joints and any other joints in concrete slabs or between slabs and foundation walls should be sealed with a caulk or sealant.
  • Gaps and joints should be cleared of loose material and filled with polyurethane caulk or other elastomeric sealant applied in accordance with the manufacturer’s recommendations.

Sump Pits

  • Although not a best practice, sump pits may be used as a primary suction point in sub-slab depressurization.
  • Sumps used as a floor drain should have a lid equipped with a trapped inlet.
  • Sump pits open to soil or serving as the termination point for sub-slab or exterior drain tile loops should be covered with a gasketed or otherwise sealed lid.

Hollow Block Masonry

  • Proactive New Construction Design Requirements:
  • Hollow block masonry foundation walls must be constructed with either a continuous course of solid masonry, one course of masonry grouted solid, or a solid concrete beam at or above finished ground surface to prevent passage of air from the interior of the wall into the living space.
  • Where a brick veneer or other masonry ledge is installed, the course immediately below that ledge must be sealed.
  • Joints, cracks or other openings around all penetrations of both exterior and interior surfaces of masonry block or wood foundation walls below the ground surface must be filled with polyurethane caulk or equivalent sealant.
  • Penetrations of concrete walls must be filled.
  • Void spaces to the hollow block masonry foundation walls should be filled/sealed to prevent the passage of radon gas.

Vented Crawlspaces

  • Sometimes crawlspaces must be provided with vents to the exterior of the building.
  • The minimum net area of ventilation openings must comply with Section R408 of the 2012 International Residential Code for One- and Two-Family Dwellings (copyrighted 2011 by the International Code Council, Inc.).
  • Air-handling units in crawlspaces must be sealed to prevent air from being drawn into the unit.
    • Units with gasketed seams or units that are otherwise sealed by the manufacturer to prevent leakage are exempted from this requirement.
  • Ductwork passing through or beneath a slab must be of seamless material unless the air-handling system is designed to maintain continuous positive pressure within the ducting.
    • Joints in the ductwork must be sealed to prevent air leakage. Ductwork located in crawlspaces must have all seams and joints sealed by closure systems in accordance with Section M1601.4.1 of the 2012 International Residential Code for One- and Two-Family Dwellings (copyrighted 2011 by the International Code Council, Inc.).
  • Openings around all penetrations through floors above crawlspaces must be caulked or otherwise filled to prevent air leakage.
  • Access doors and other openings or penetrations between basements and adjoining crawlspaces must be closed, gasketed or otherwise filled to prevent air leakage.