Q. What is the Canadian guideline for radon in indoor air?

A. the Canadian guideline for radon 
indoor air provides Canadians with guidance on when remedial action should be taken to reduce radon levels. The Canadian Guideline is as follows:

"Remedial measures should be undertaken in a dwelling whenever the average annual radon concentration exceeds 200 Becquerels per cubic meter (200 Bq/m³) in the normal occupancy area. The construction of new dwellings should employ techniques that will minimize radon entry and will facilitate post-construction radon removal, should this subsequently prove necessary."

The Builders Code states: Application and Scope

1)    This Subsection applies to

a)    wall, roof, and floor assemblies separating conditioned space from the ground, and

b)    the rough-in to allow the future protection of conditioned space that is separated from the ground by a wall, roof or floor assembly.

2)    This Subsection addresses the leakage of soil gas from the ground into the building Protection from Soil Gas Ingress

2)    Unless the space between the air barrier system and the ground is designed to be accessible for the future installation of a sub-floor depressurization system, dwelling units and buildings containing residential occupancies shall be provided with the rough-in for a radon extraction system conforming to Article Providing Rough-in for a Sub-floor Depressurization System

3)  (b)(i) its bottom end opens into the granular layer required Clause (a) at or near the center of the floor and not less than 100mm of granular material projects beyond the terminus of the pipe measured along its axis (see A- and (3)(b)(i) in Appendix A)

3)  (b)(ii) its top end permits connection to depressurization equipment and is provided with an airtight cap, and

3) (b)(iii) the pipe is clearly labelled near the cap and, if applicable, every 1.8m and at every change in direction to indicate that it is intended only for the removal of radon from below the floor-on-ground.

Soil Gas Control and Radon – NBC Part 5, Part 6 and Part 9

The new Health Canada guideline of 200Bq/m3 for indoor radon concentration has been referenced in the Appendix. Parts 5 and 6 now require that engineers and designers consider radon protection in their designs. Air barrier requirements were moved from 9.13 and placed with other air barrier requirements in 9.25. These prescriptive requirements were added:

·        Polyethylene solid gas barrier is required under slab;

·        Slab perimeter must be sealed to wall;

·        All penetrations through the slab must be sealed;

·        Sump pit cover to be airtight;

·        Granular fill required under the slab;

·        A rough-in for radon extraction to either performance or prescriptive requirements must be installed.