ASK AN EXPERT
Exposed
mass timber
I want to expose as much of the mass timber structure as possible in my upcoming project. I have limited experience designing with mass timber. How can I easily evaluate how much of the wood I can expose, and how much has to be protected?
In encapsulated mass timber construction (EMTC), the National Building Code of Canada (NBCC) permits a defined amount of mass timber that is permitted to be exposed, while overall fire performance is maintained through a combination of encapsulation, minimum member dimensions, and other prescriptive requirements. Determining how much wood can be exposed therefore depends on how these factors come together within a given compartment.
To support this early-stage evaluation, the Canadian Wood Council has developed the Exposed Mass Timber Calculator. This free web-based tool allows users to input key characteristics of a proposed suite or fire compartment and evaluate those inputs against the applicable requirements of the 2025 National Building Code of Canada.
Based on this information, the tool indicates whether a given configuration aligns with the requirements of the NBCC, helping to identify potential constraints related to encapsulation and allowable exposure. It can be a useful way to explore design options and better understand how exposed and encapsulated elements can be balanced within permitted limits.
How can one determine the Fire Resistance Rating (FRR) and Sound Transmission Coefficient (STC) ratings for wood stud shear walls that include plywood on one or both sides and are finished with gypsum? To achieve a 1-hour rating, is it possible to use an existing tested gypsum assembly to meet both FRR and STC requirements and simply add plywood without affecting the ratings? Is there a better way to determine the FRR and STC ratings in this scenario?
The calculator is intended as a screening and learning aid to support early decision-making. It does not replace detailed code analysis or professional judgment, and final design should always be confirmed through the NBCC and applicable standards.
Access the Exposed Mass Timber Calculator here
ASK AN EXPERT
Non-combustible stair and elevator cores in
6-storey wood buildings
I understand that the requirement for
non-combustible stair and elevator cores in
6-storey wood buildings has changed in Ontario. Where can I find guidance on the most recent changes affecting wood construction in the province?
Recent updates to the Ontario Building Code have introduced important changes affecting mid-rise wood construction, including provisions that now permit combustible construction for elements such as exit stair shafts. These changes, which came into effect with the 2024 Ontario Building Code (O. Reg. 163/24), reflect broader alignment with the 2020 National Building Code of Canada and introduce greater flexibility for 5- and 6-storey wood buildings.
To help navigate these updates, the Guide to Mid-Rise Wood Construction in the Ontario Building Code (Second Edition) provides a practical overview of current code pathways and requirements. Originally developed when mid-rise combustible construction was first introduced, this updated edition reflects the latest code changes, including revised references and new technical resources.
The guide is intended to support architects, engineers, developers, and other construction professionals in interpreting and applying OBC provisions, while also directing readers to additional best-practice resources. As a concise reference, it can help project teams better understand how recent regulatory changes, including those affecting exit construction, may influence design decisions.
For those working on mid-rise wood buildings in Ontario, the guide is available as a free online resource and serves as a useful starting point for understanding the current code framework. The Guide focuses on new construction and is intended to be used in conjunction with the Ontario Building Code.
How can one determine the Fire Resistance Rating (FRR) and Sound Transmission Coefficient (STC) ratings for wood stud shear walls that include plywood on one or both sides and are finished with gypsum? To achieve a 1-hour rating, is it possible to use an existing tested gypsum assembly to meet both FRR and STC requirements and simply add plywood without affecting the ratings? Is there a better way to determine the FRR and STC ratings in this scenario?
Download a copy of the guide here
ASK AN EXPERT
Exposed
mass timber
I want to expose as much of the mass timber structure as possible in my upcoming project. I have limited experience designing with mass timber. How can I easily evaluate how much of the wood I can expose, and how much has to be protected?
In encapsulated mass timber construction (EMTC), the National Building Code of Canada (NBCC) permits a defined amount of mass timber that is permitted to be exposed, while overall fire performance is maintained through a combination of encapsulation, minimum member dimensions, and other prescriptive requirements. Determining how much wood can be exposed therefore depends on how these factors come together within a given compartment.
To support this early-stage evaluation, the Canadian Wood Council has developed the Exposed Mass Timber Calculator. This free web-based tool allows users to input key characteristics of a proposed suite or fire compartment and evaluate those inputs against the applicable requirements of the 2025 National Building Code of Canada.
Based on this information, the tool indicates whether a given configuration aligns with the requirements of the NBCC, helping to identify potential constraints related to encapsulation and allowable exposure. It can be a useful way to explore design options and better understand how exposed and encapsulated elements can be balanced within permitted limits.
The calculator is intended as a screening and learning aid to support early decision-making. It does not replace detailed code analysis or professional judgment, and final design should always be confirmed through the NBCC and applicable standards.
Ensuring appropriate long-term protection, such as using membranes, sealants and other permanent protective systems, is crucial in safeguarding the durability and reliability of the connection.
Access the Exposed Mass Timber Calculator here
ASK AN EXPERT
Non-combustible stair and elevator cores in
6-storey wood buildings
I understand that the requirement for
non-combustible stair and elevator cores in
6-storey wood buildings has changed in Ontario. Where can I find guidance on the most recent changes affecting wood construction in the province?
Recent updates to the Ontario Building Code have introduced important changes affecting mid-rise wood construction, including provisions that now permit combustible construction for elements such as exit stair shafts. These changes, which came into effect with the 2024 Ontario Building Code (O. Reg. 163/24), reflect broader alignment with the 2020 National Building Code of Canada and introduce greater flexibility for 5- and 6-storey wood buildings.
To help navigate these updates, the Guide to Mid-Rise Wood Construction in the Ontario Building Code (Second Edition) provides a practical overview of current code pathways and requirements. Originally developed when mid-rise combustible construction was first introduced, this updated edition reflects the latest code changes, including revised references and new technical resources.
The guide is intended to support architects, engineers, developers, and other construction professionals in interpreting and applying OBC provisions, while also directing readers to additional best-practice resources. As a concise reference, it can help project teams better understand how recent regulatory changes, including those affecting exit construction, may influence design decisions.
For those working on mid-rise wood buildings in Ontario, the guide is available as a free online resource and serves as a useful starting point for understanding the current code framework. The Guide focuses on new construction and is intended to be used in conjunction with the Ontario Building Code.
Download a copy of the guide here