The National Model Code Committee on Indoor Environment met to review Proposed Change Form (PCF) 2160, “Active Side Wall Radon Stack,” recommended by the Radon Task Group for inclusion in the 2030 NBC. Codes Canada staff emphasized the urgency of advancing the PCF for spring public review to enable early adoption by provinces and territories alongside the 2025 passive stack requirement.

The National Research Council (NRC) presented supporting research, while Codes Canada outlined PCF 2160’s technical requirements would deliver equivalent performance to a passive stack, specifying airflow between 14 l/s and 28 l/s. NRC’s research addressed prior concerns about depressurization risks from radon mitigation fans.

CHBA suggested revisiting the “Smart Regulation” criteria for new code requirements introduced to the NMCC in June 2025 prior to review of the proposed change, but time constraints prevented discussion. Members raised observations and concerns, notably CHBA’s question on whether radon mitigation contractors commonly measure flow rates within a range. CHBA warned this limitation could challenge builders aiming to reduce radon below Health Canada’s action level of 200 Bq/m³, especially if adjusting flow rates above 28 l/s would result in non-compliance with the Code. This could also present challenges for harmonization of the radon requirements. A Yukon representative noted flow rate measurements have been standard there since 2009, though national practices remain unclear.  A radon mitigation contractor representing the Canadian Association of Radon Scientists and Technologists (CARST) raised a number of concerns with the PCF, including the potential for oversized fans being installed. One of the meeting participants also pointed out that the 14-28 l/s range differs from AARST guidelines in the United States based on the area of a floor slab.

Many questions could not be addressed due to time constraints and the Committee lost quorum in overtime. The chair advised that Codes Canada will follow up with NMCC members to determine consensus on PCF 2160. CHBA is not a voting (consensus) member.

The agenda package can be downloaded from the link below.

For any questions, please contact Jack.Mantyla@chba.ca