Requirements for Soil Gas Control and Radon Testing

Posted on Friday January 13, 2017

MIDLAND PENETANGUISHENE BUILDING SERVICES                               

 

REMINDER-REQUIREMENTS FOR SOIL GAS CONTROL

This is a reminder of the requirements for soil gas control as per Division C, Part 9, Section 9.13.4.2. and SB-9 of the Ontario Building Code. These requirements are for all floors-on-ground except in garages and unenclosed portions of buildings.  The responsibility is on the builder and/or contractor and/or owner to comply with one of the options listed below.

Option #1: Install Soil Gas Pipe, Mandatory Radon Testing

  • Install a minimum of 100mm of coarse clean granular material containing not more than 10% of material that will pass a 4mm sieve below all floors-on-ground.
  • Provide for possible installation of a sub-floor depressurization on all floors-on-ground by installing a minimum 4” diameter pipe (PVC or ABS) vertically through the floor, at or near its centre, such that its bottom end opens into the granular fill below the slab and its top end will permit connection to depressurization equipment if required.
  • The granular fill near the centre of the floor-on-ground, where the pipe is installed, shall not be less than 150mm deep for a radius of not less than 300mm centred on the pipe.
  • The upper end of the pipe shall be provided with a removable seal.
  • The pipe shall be clearly labelled to indicate that it is intended only for the removal of soil gas from below the floor-on-ground.
  • After the building is complete, testing for radon shall be conducted according to HC Pub. 4171, “Guide for Radon Measurements in Residential Dwellings (Homes), 2008 to determine the radon concentration in the building.  A copy of the test results shall be provided by the owner of the building to the Town of Midland or Penetanguishene Building Department. The testing shall include basement concentration measurements.
  • Where the average annual radon concentration as determined from the testing exceeds 200 Bq/cubic metre in the normal occupancy area, a subfloor depressurization system shall be installed to reduce the radon concentration to a level below 200 Bq/cubic metre in the normal occupancy area.
    • Where a subfloor depressurization system is installed, makeup air shall be provided as specified in Article 9.32.3.8. of Division B of the OBC and measures shall be taken to ensure that any resultant decrease in soil temperature will not adversely affect the foundation.

Option #2:  Soil Gas Barrier, Voluntary Radon Testing

  • Install a minimum of 100mm of coarse clean granular material containing not more than 10% of material that will pass a 4mm sieve below all floors-on-ground.
  • In the case of a concrete block foundation wall, the first course of block shall not contain voids.
  • Any floor-on-ground shall be sealed to the foundation walls with a bead of flexible sealant.
  • Any floor-on-ground shall have a soil gas barrier installed below the floor-on-ground or applied on top of the floor-on-ground if a separate floor is installed over the floor-on-ground.
  • The soil gas barrier shall consist of 6 mil poly.  Joints shall be lapped a minimum of 300mm.
  • All penetrations of the soil gas barrier shall be sealed.
  • Radon testing is voluntary.

Option#3: Installation of a Subfloor Depressurization System

  • Install a subfloor depressurization system, makeup air shall be provided as specified in Article 9.32.3.8. of Division B of the OBC and measures shall be taken to ensure that any resultant decrease in soil temperature will not adversely affect the foundation.
  • Radon testing is voluntary.