Radon Gas Mitigation Program

Although radon gas exists everywhere, there is good news: The City is proactively addressing radon gas in new buildings and additions through the Radon Gas Mitigation Program.

This program applies to all building permits applied for after August 31, 2015.

The City’s Radon Gas Mitigation Program aims to:

  • Create an effective radon gas mitigation program,
  • Proactively address potential exposure to radon gas, and
  • Reduce potential health risks to building occupants.

What is radon gas?

Radon is a colourless, odourless and tasteless radioactive gas that forms when uranium in soil, rock and water breaks down. Radon gas seeps into homes and buildings through cracks and holes in floors and foundations.

According to Health Canada, long-term exposure to radon is linked to roughly 16 per cent of lung cancer deaths in Canada and is the second leading cause of lung cancer after smoking. Canada’s radon guideline is 200 becquerels per cubic metre (Bq/m3).

Radon gas in Guelph

According to the results from residential surveys completed by Health Canada, 18 per cent of the 131 randomly tested buildings within the City of Guelph exceed Canada’s recommended guideline for radon gas.

For more information

Nicholas Rosenberg, Technical Services Specialist
Building Services
519-837-5615 extension 2285
nicholas.rosenberg@guelph.ca

New homes

As part of the Radon Gas Mitigation Program, all new low-rise residential dwellings will require radon gas mitigation measures in compliance with the Ontario Building Code.

The program requires a builder to implement one of the following three radon gas mitigation options when constructing a new low-rise residential dwelling:

Option #1

  • rough-in soil gas pipe, and
  • mandatory radon gas testing

Option #2

  • soil gas barrier on the foundation walls,
  • soil gas barrier under the basement floor slab, and

Option #3

  • soil gas barrier on the foundation walls,
  • active sub-slab depressurization system, and

Building permit drawings shall clearly indicate details associated with the chosen option.

Radon gas testing

Based on the radon gas mitigation option chosen by the home builder, a home may be subject to mandatory radon gas testing.

All radon gas testing will consist of long-term tests (minimum 91 days) completed during the winter season, when windows and doors are generally closed, and must be carried out by a Canadian National Radon Proficiency Program (C-NRPP) certified professional.

Although all new homes aren’t subject to mandatory testing, Health Canada recommends that all buildings be tested for radon gas.

Test results

Where mandatory radon gas testing results come back over 200 becquerels per cubic metre (Bq/m3), the builder will be responsible for remediation work.

Information for new home owners

As a new home owner, your home will be built in compliance with one of the three radon gas mitigation options in the Ontario Building Code.

All new homes in Ontario come with a new home warranty that is provided by your builder and backed by Tarion. This warranty also covers excessive radon gas levels in new homes.

Residential additions

As part of the Radon Gas Mitigation Program, all low-rise residential additions that exceed 20 metres square (m²) will require radon gas mitigation measures to be implemented in compliance with the Ontario Building Code.

The program requires one of the following three radon gas mitigation options to be implemented when constructing a residential addition that exceeds 20 m²:

Option #1

  • rough-in soil gas pipe, and
  • mandatory radon gas testing

Option #2

  • soil gas barrier on the foundation walls, and
  • soil gas barrier under the basement floor slab

Option #3

  • soil gas barrier on the foundation walls, and
  • active sub-slab depressurization system

Building permit drawings shall clearly indicate details associated with the chosen option.

Compliance with option #1 may carry certain risks. Depending on the age and characteristics of the existing building the results of a radon test can vary greatly, which could have a negative effect on the overall level of radon gas in the building. For this reason, compliance with option #2 or #3 may be more desirable for residential additions.

Radon gas testing

Based on the radon gas mitigation option chosen by the applicant, an addition may be subject to mandatory long-term radon gas testing.

All initial radon gas testing will consist of long-term tests (minimum 91 days) completed during the winter season, when windows and doors are generally closed. All radon gas testing shall be carried out by a Canadian National Radon Proficiency Program (C-NRPP) certified professional.

Although all additions won’t be subject to mandatory testing, Health Canada recommends that all buildings be tested for radon gas.

Test results

Where mandatory radon gas testing results come back over 200 Bq/m3, the builder will be responsible for remediation work and follow-up testing.

New industrial, commercial, institutional and multi-residential buildings

As part of the Radon Gas Mitigation Program, all new buildings and all industrial, commercial, institutional and non-low-rise multi-residential additions that exceed 50 metres square (m²) in building area shall be designed and constructed in accordance with the radon mitigation requirements in the Ontario Building Code. These requirements include:

    1. Sealing of walls (e.g. bituminous damproofing), roofs (e.g. suitable waterproofing membrane) and floors (e.g. 6 mil polyethylene sheet) that are in contact with the soil, including connections and any penetrations through them,
    2. Pipe rough-in only of an active soil depressurization system,
    3. Mandatory long-term testing (min. 91 days during winter months), and
    4. Installation of a full active soil depressurization system if concentration levels measured by long-term testing exceed 200 Bq/m3.

Program overview

A full overview of the Radon Mitigation Program from design through to occupancy is outlined in a comprehensive flow diagram. The diagram details the building permit application process, required site inspections, submission of documentation, testing, and permit close-out. We encourage you to refer to this diagram throughout the project.

To provide further guidance, a letter with supporting attachments was issued to Architects, Professional Engineers, ICI Contractors and other stakeholders on November 4, 2015.

To obtain a copy of the flow diagram and letter, please contact Patrick Andres, Technical Lead Resource Conservation at 519-837-5615 extension 3478 or patrick.andres@guelph.ca

Building permit applications

All permit applications for new buildings, and for additions that exceed 50 m², will need to include a complete copy the City of Guelph Radon Mitigation Certification Form. The notes provided on the back of this form indicate the design professionals that are permitted to take responsibility for the radon mitigation measures.

Building permit drawings must clearly indicate all aspects of the required radon mitigation measures.

If applicable, designers intending to submit with alternative design solutions must include all relevant documentation with the permit application. This includes a signed letter stating that the Level of Performance delivered will meet or exceed that required in the Ontario Building Code and/or EPA/625/R-92/016 document and shall list the standard and/or guideline that was used. Designers will be notified if a formal “Application for an Alternative Solution” is required after the permit application has been reviewed.

Inspections

Prior to the start of construction, Contractors are encouraged to schedule an initial meeting with the Resource Conservation Inspector by calling 519-837-5614. The Inspector will meet with the Contractor onsite to discuss the radon mitigation measures that are proposed for the project, outline the overall inspection and testing process, and review when to book inspections.

The Radon Gas Mitigation Program requires up to five City inspections for each project. The construction milestones and inspection process is outlined in the flow diagram highlighted under the “Program Overview” section of this page. Inspection requests are made by calling 519-837-5614.

After all radon mitigation measures have been installed, the individual(s) taking responsibility is required to submit a General Review letter to the City inspector confirming that the installation complies with the design. A copy of the HVAC airflow balancing report is also required after HVAC systems have been balanced.

Radon gas testing

After construction is complete, a long-term radon concentration test (minimum 91 days) must be completed during the heating season as recommended by Health Canada, when windows and doors are generally closed. All testing must be carried out by a C-NRPP certified “Radon Measurement Professional” and must follow all applicable sections in Health Canada Publication 4175, “Guide for Radon Measurements in Public Buildings”.

Before the building permit can be closed, a radon analysis certificate showing that the radon concentration level does not exceed 200 Bq/m3 must be submitted to the Inspector.

For a complete directory of C-NRPP certified professionals, please visit the Canadian – National Radon Proficiency Program website.

Additional information

For additional information regarding the Radon Gas Mitigation Program as it applies to industrial, commercial, institutional & non-low-rise multi-unit residential buildings, please contact Patrick Andres, Technical Lead Resource Conservation at 519-837-5615 extension 3478 or patrick.andres@guelph.ca.

Existing buildings

Including houses, apartment buildings, schools, malls and offices

Regardless of the age or location of a building, Health Canada recommends that all homes and other buildings be tested for radon gas. Remedial measures should be undertaken when the average annual radon concentration level exceeds 200 Bq/m3.

It is recommended that radon testing be carried out by a certified Radon Measurement Professional, and radon mitigation be carried out by a certified Radon Mitigation Professional. Find a certified radon professional.

If you have questions or concerns about the health effects of radon gas, or to learn more about testing and mitigation options, contact Wellington-Dufferin-Guelph Public Health or Health Canada.

The Ontario Building Code regulates new construction only and does not contain retrofit requirements for radon gas. The program is only able to address radon gas mitigation in new construction.

For more information

Wellington-Dufferin-Guelph Public Health
1-800-265-7293 extension 4753
info@wdgpublichealth.ca
wdgpublichealth.ca/?q=adultradon

Health Canada
613-946-6384 or 613-948-3232
radon@hc-sc.gc.ca
healthcanada.gc.ca/radon