Significant technical changes – 2025 National Model Codes

Large farm buildings

• Revises the application of the OP objective (fire and structural protection of buildings) to permit the application of the OP3 sub-objective (protection of adjacent buildings from fire) to large farm buildings.
• Introduces technical requirements in Part 2 for the spatial separation and exposure protection of large farm buildings, which generally refer to Subsection 3.2.3. and provide certain exemptions.

Protective coverings over foamed plastic insulation

Adds a compliance path for the testing of assemblies incorporating protective coverings over thermosetting foamed plastic insulation by referencing a new standard test method in Part 3 and, through reference, Part 9 as well.

Encapsulated mass timber construction (EMTC)

• Increases the maximum physical height for EMTC buildings to 50 m, while maintaining the maximum of 12 storeys,
• Permits increased exposure of mass timber elements in finished buildings and adds a new encapsulation option.

Limiting distances and areas of unprotected openings

Updates Tables 3.2.3.1.-C to -E with values calculated directly from the original equation, and introduces the equation in an explanatory Note, which indicates that linear interpolation may be used to determine values between the entries in Tables 3.2.3.1.-B to -E.

Adaptable and visitable dwelling units

• Expands the accessibility objective to apply to all types of dwelling units, with flexibility provided for provinces and territories to adjust the application of requirements to suit local needs.
• Adds new Subsection 3.8.4. for adaptable dwelling units, which introduces requirements for the reinforcement of stud walls around water closets, showers and bathtubs to allow for the future installation of grab bars.
• Introduces requirements for low-cost adaptability features to accommodate occupants’ changing needs, including a wider entrance and reachable controls (such as light switches and electrical outlets).
• Adds new Subsection 3.8.5. for visitable dwelling units, which applies to designated units in multi-unit residential buildings.
• Requires visitable units to have both the new adaptability features and additional visitability features, including wider paths of travel and a washroom with sufficient space to manoeuvre a mobility aid on the entrance level.

Update to design approach

• Revises specified wind and snow loads in Part 4 to reflect “uniform risk” by reducing load factors for wind and snow to 1.0 and by using 1/500 annual probability wind loads and 1/1000 annual probability snow loads.
• Revises the snow load formula by adjusting the wind exposure factor (C_w) and the accumulation factor (C_a) to account for differences in the winter average temperature (T_ws) and winter average wind speed (V_ws) across Canada, and by introducing a thermal factor (C_T) to account for a reduction in snow depth due to heat loss through the roof and aligns Part 9 with the changes to wind and snow loading in Part 4.

Structural and non-structural elements not part of the seismic force resisting system

Resolves ambiguity in the provisions for structural and non-structural elements that are not part of the designated seismic force resisting system (SFRS).

Wind resistance of vegetated roof assemblies

Introduces requirements for the determination of acceptable wind loads for the design of vegetated roof assemblies.

Radon and soil gas mitigation

• Introduces a requirement to provide a passive vertical radon stack in dwelling units and home-type care occupancies where a floor assembly separates a conditioned space from the ground.
• Requires the overlapping seams of air barriers under concrete slabs to be sealed, and clarifies the type and thickness of ballast to be applied over exposed air barriers in heated crawl spaces.

Lateral loads

Updates the seismic design parameter used in Part 9 from S_a(0.2) to S_max, adds new prescriptive framing types options for braced wall panels, and extends requirements for bracing to resist lateral loads to locations with low seismic and wind loads.

Wall studs

Revises Table 9.23.10.1., Size and Spacing of Studs, to clarify that 38 mm × 140 mm studs spaced at 400 mm can be used in exterior walls supporting a roof or a roof plus one floor.

Protection from precipitation of rough opening sills

Clarifies the requirements for protection from precipitation of rough opening sills for windows and doors to improve alignment with established building science principles and standards.

Thermal characteristics of fenestration and doors

Places an upper limit on the solar heat gain coefficient for fenestration and doors that depends on the fenestration and door area to gross wall area ratio (FDWR) and the climate zone of the building location.

Energy use intensity path

Introduces an optional energy use intensity path in which compliance with the energy performance tiers is demonstrated by meeting an annual energy consumption target, an annual gross space heat loss target, and a design cooling load budget and that recognizes the inherent energy savings of smaller and more compact housing forms.

Points-based prescriptive trade-off path

• Revises the optional energy conservation measures, and corresponding points, available in the prescriptive trade-off path for demonstrating compliance with the energy performance tiers, including updates related to drain-water heat-recovery units, oil- and gas-fired furnaces, air-source heat pumps, heat/energy recovery ventilators, the building envelope, airtightness, and fenestration and doors.
• Sets the minimum sums of energy conservation points required for compliance with Energy Performance Tiers 3, 4 and 5.

Prescriptive compliance for Energy Performance Tiers 1 and 5

Provides an optional simple set of prescriptive energy efficiency requirements for demonstrating compliance with Energy Performance Tiers 1 and 5.

Operational greenhouse gas emissions

Introduces both performance and prescriptive requirements, within a framework of gradually increasing reduction levels, to establish limits for operational greenhouse gas emissions resulting from the supply and consumption of energy used by the building, as determined at the time of design.

Alteration of existing buildings

• Introduces a new Part that applies to the alteration of existing buildings to clarify the application of requirements to improve the energy performance of HVAC and service water heating systems, above-ground opaque and below-grade assemblies, fenestration, doors and skylights, and the airtightness of air barrier systems in existing Part 9 buildings subjected to alteration.
• Introduces the defined terms “existing building” and “heritage building.”

Updates to climatic data

Updates the climatic design data in Table C-2 by taking into consideration projected future changes over a 50-year time horizon.

Large farm buildings

Revises the application of the OP objective (fire protection of buildings and facilities) to permit the application of the OP3 sub-objective (protection of adjacent buildings or facilities from fire) to large farm buildings and attributes the OP3 sub-objective to specific existing requirements in Part 4 related to spatial separation.

Aboveground storage tanks

Removes the capacity restriction for aboveground storage tanks from the reference to CSA B139 Series:24, “Installation code for oil-burning equipment”.

Dangerous goods for use in laboratories

• Clarifies the maximum quantities of dangerous goods that are permitted to be available for use during normal operations in a laboratory, which include quantities that are in use for experiments.
• Introduces maximum quantities of dangerous goods classified as compressed gases that are permitted to be kept in the open area of a laboratory to harmonize with NFPA 55-2020, “Compressed Gases and Cryogenic Fluids Code.”

Encapsulated mass timber construction (EMTC)

• Permits increased exposure of mass timber elements during construction to align with related changes in the NBC.
• Introduces additional measures to reduce the risk of fire spread between storeys of EMTC buildings during construction, including performance and prescriptive options.

Defined terms

Introduces the defined terms “washroom,” “public washroom,” “private washroom” and “macerating toilet system,” and revises the defined terms “public use” and “private use.”

Condensate drainage

• Introduces the defined term “condensate drainage system,” and revises the defined terms “clear-water waste” and “drainage system” to address condensate drainage.
• Introduces requirements for condensate drainage systems.

Storm and sanitary drainage systems

• Clarifies the requirements for the storm drainage systems of roofs with certain configurations , including the use of scuppers or emergency roof drains, and provides additional options for the design of the storm drainage systems.
• Requires storm and sanitary drainage systems to be labeled according to their application to allow contractors and municipal plumbing inspectors to differentiate between them.

Wall carriers for water closets

Introduces a reference to ASME A112.6.1M-1997, “Floor-Affixed Supports for Off-The-Floor Plumbing Fixtures for Public Use,” to establish minimum requirements for wall carriers for water closets.

Oil separators

Introduces a reference to CAN/ULC-S656-14, “Standard for Oil-Water Separators” to establish minimum requirements for oil separators (also referred to as “oil interceptors”).

Protection of potable water

• Adds references to NSF/ANSI/CAN 61-2020, “Drinking Water System Components - Health Effects,” to address the protection of potable water from chemical contamination.
• Introduces a reference to CSA B214:21, "Installation code for hydronic heating systems," to address the protection of potable water used as a hydronic fluid in an open-loop heating system.

Mechanical couplings

Introduces a reference to ANSI/AWWA C227-17, “Bolted, Split-Sleeve Couplings,” to establish minimum requirements for plain-end-type mechanical couplings for pressure applications.

Neutralization tanks

Removes dilution as an option for treating corrosive or acid waste, while retaining neutralization, to align the NPC with local sewer use bylaws.

Thermal bridging

• Updates the thermal bridging requirements in Part 3 and adds a reference to CSA Z5010:21, “Thermal bridging calculation methodology,” to provide guidelines for thermal simulation.
• Requires that thermal bridging due to fasteners and other point elements that penetrate the insulation layer be accounted for in the calculation of thermal resistance of the assembly.

Application of Part 4

Clarifies that Part 4 applies to lighting components and systems that are in the building, connected to the building’s electrical service, or located on the building site.

Energy modeling software

• Requires the energy modeling software used to demonstrate code compliance pass the acceptance criteria set out in ASHRAE 140-2023, “Method of Test for Evaluating Building Performance Simulation Software.”
• Introduces requirements for exceptional calculation methods, and for related documentation, for building components that cannot be modeled by the energy modeling software.

Energy use intensity compliance path

Introduces an optional energy use intensity compliance path for multi-unit residential buildings, schools and office buildings, in which the annual energy consumption of the proposed building is compared with a building energy target based on the energy use intensity of the building archetype and that recognizes the inherent energy savings of smaller and more compact architectural forms.

Operational greenhouse gas emissions

Introduces performance requirements within a framework of gradually increasing reduction levels to establish limits for operational greenhouse gas emissions resulting from the supply and consumption of energy used by the building, as determined at the time of design.

Alteration of existing buildings

• Introduces a new Part that applies to the alteration of existing buildings to clarify the application of requirements for the energy performance of the building envelope and of HVAC, service water, lighting and electrical power systems in existing buildings subjected to alteration.
• Introduces the defined terms “existing building” and “heritage building.”

Updates to climatic data

Updates the climatic data in Table C-1 to include projected future values of July design temperatures and hourly wind pressures that incorporate the effects of climate change.