What's changing?

Requirement for a passive vertical radon stack in dwelling units to reduce radon exposure.

(This change is more than just the passive radon stack)

  • 9.13.4.1. Application and Scope
    • (a) & (b) – introduction of “conditioned space”
    • (c) – new sentence - a passive vertical radon stack for a conditioned space that has a wall, roof or floor assembly that is in contact with the ground.
    • 9.13.4.2. Protection from Soil Gas Ingress
      • (1) – modified - introducing specific reference to that provided by 0.15 mm polyethylene sheet conforming to CAN/CGSB-51.34, “Polyethylene sheet for use in building construction– Material specification.”
      • (2) – modified – except for sentence (4), dwelling units and home-type care occupancies where a floor assembly separates a conditioned space from the ground shall be provided with a passive vertical radon stack, and
      • (4) – new – outlines entrance at grade with direct access to a stairway (exemptions).
    • 9.13.4.3. Rough-in for a Subfloor Depressurization System
      • (3)(b) – modified- clarifies the continuity requirements and adds explicit performance‑based language and more prescriptive detailing expectations for a passive vertical stack.
    • 9.13.4.4. Passive Vertical Radon Stack (NEW)

Yukon builders will be required to show the radon system(s) on the permit application drawings and must coordinate routing, sealing, and rough‑in placement to meet the new national radon performance requirements.

Snow Loads

  • 9.4.2.2. Specified Snow loads (Modified)
  • The NBC 2025 has modified the snow and rain load factors from the 1-in-50-year to a 1-in-1 000 annual probability ground snow and rain loads.

Why the change?

Data shows increasing variability and more extreme precipitation events, especially rain‑on‑snow.

  • The 50‑year basis was no longer representative of future risk.
  • The 1‑in‑1 000 basis provides:
    • Higher reliability for roof structural safety
    • Better resilience for long‑life buildings
    • Reduced risk of catastrophic roof failures under extreme snow + rain events

Affects to Part 9 Housing

  • Prescriptive tables in 9.4.2 will show higher required specified snow loads for many climatic zones.
  • Truss manufacturers will update their standard tables.
  • Authorities Having Jurisdictions (AHJs) may see more engineered roof designs in high‑snow regions.

Yukon builders have already flagged snow load changes as a major adoption issue.

Communities with historically high snow loads (e.g., Whitehorse, Dawson, Watson Lake) may see:

  • Noticeable increases in required roof capacity
  • More engineered solutions for additions, carports, and accessory structures
  • Greater scrutiny of rain‑on‑snow combinations during permit review

Wind Loads

9.4.2.3. Reference Hourly Wind Pressure (NEW)

  • The NBC 2025 has introduced Article 9.4.2.3 outlining the reference hourly wind pressures (1/500-year “uniform risk” hazard level) to be used for Part 9 structural design. These values are the climatic wind pressures that drive:
    • Braced wall panel requirements
    • Sheathing thickness and fastening
    • Anchorage of roofs and walls
    • Overall lateral load resistance for small buildings

Yukon builders will see stronger wind pressures, more braced wall panels, tighter fastening schedules, and updated engineered components. Exposed sites will feel the biggest impact.

9.4.2.6. Seismic Design Parameter (Modified)

(See Note A-9.4.2.6.)

1) Except as provided in Sentence(2) and unless otherwise indicated, the value of the seismic design parameter, Smax, at a location listed in Table C-3 of Appendix C shall

Be taken as Smax for unknown Site Class.(SeeNoteA-9.4.2.6.(1).)

2) Where the Site Class is determined in accordance with Sentence 4.1.8.4.(3),the value of the seismic design parameter, Smax, at a location listed in Table C-3 of Appendix C, is permitted to be taken as Smax for the determined Site Class.(SeeNoteA-9.4.2.6.(2).)

9.31.6.2. Equipment and Installation (Modified)

3) Where the building is in a location where the seismic design parameter, Smax, for Site Class C is greater than 0.37, service water heaters shall be secured to the structure to prevent overturning. (See Note A-9.31.6.2.(3).)

Table C-2 Climatic Design Data for Selected Locations in Canada (Modified)

Table C-3 Seismic Design Parameter, Smax, for Selected Locations in Canada (Modified)

Yukon builders will see changes to seismic bracing for lateral loads (structural bracing), insulated concrete forms, hot water tanks and heating or cooling equipment. These changes will mainly affect new builds in Aishihik, Dawson, Snag and Destruction Bay.

This framework offers provinces and territories a pathway to reduce emissions over time by choosing the performance level that best suits their needs - Section 9.36. Energy Efficiency.

9.36.1.1. Scope (Modified)

1) This Section is concerned with the energy used by buildings, and GHG emissions resulting from the supply and consumption of that energy, as a result of

a) the design and construction of the building envelope, and

b) the design and construction or specification of systems and equipment for

i) heating, ventilating or air-conditioning, and

ii) service water heating.

(See Note A-9.36.1.1.(1).)

9.36.1.2. Definitions (New)

9) For the purposes of this Section, the term “house” shall mean all houses, with or without a secondary suite, that

a) have HVAC systems that serve only the house, only the secondary suite, or both the house and the secondary suite,

b) have service water heating systems that serve only the house, only the secondary suite, or both the house and the secondary suite, and

c) do not share common spaces intended for occupancy with other dwelling units or houses, except for a secondary suite.

Yukon building industry partners are encouraged to also review modification within Articles 9.36.1.3 Compliance, 9.36.1.4. Application, and 9.36.8. Tiered Energy Compliance: Energy Use Intensity Path as well as our engagement page - Which energy tier should the Yukon select?

Introduction of energy efficiency requirements for the alteration of existing buildings and a framework to enforce code requirements in retrofits.

  • Within Volume 02 – Division B – the NBC 2025 has introduced Part 10 Alteration of Existing Buildings to create a national, consistent, enforceable framework for renovations, alterations, retrofits, and conversions of existing buildings — supporting housing supply, climate adaptation, and harmonization across Canada.
  • Section 10.9 Energy Efficiency of Housing and Small Buildings introduces national, enforceable energy‑efficiency rules for alterations of existing housing and small buildings.
    • Renovations must not reduce performance, and many must upgrade envelope, mechanical, and airtightness to modern standards.

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.

9.27.2.3. First and Second Planes of Protection (Modified)

1) c) the protection provided by the first and second planes of protection shall be

maintained

i) at the rough opening sills of windows and doors,

ii) at wall penetrations for components and services such as ventilation ducts, piping, wiring and electrical outlets, and

iii) at the interface with other wall assemblies.

9.27.3 Second Plane of Protection

(Modified)

3) The second plane of protection shall be maintained

a) at the rough opening sills of windows and doors in conformance with Sentence (4),

b) at wall penetrations for components and services such as ventilation ducts, piping, wiring and electrical outlets, and

c) at the interface with other wall assemblies.

(New)

4) The protection of rough opening sills required by Clause (3)(a) shall

a) conform to Article 9.7.6.1.,

b) extend to the interior face of the rough opening sill of the window or door assembly, and

c) be constructed of water-impermeable material that

i) is liquid-applied or self-adhered, extends up each side of the sill by at least 150 mm, and is securely adhered to the rough opening jambs, or

ii) is non-adhesive, where the sheathing membrane of the second plane of protection on the wall face extends into the rough opening to the interior face of the rough opening and down over the non-adhesive sill protection to create a drainage path to the sill

Yukon designers and builders should expect to provide additional drawing details and ensure to coordinate on-site installations.

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