Which code actually governs here
ASHRAE 90.1 is an American energy standard, and its 2022 edition made a significant addition: explicit recognition of linear thermal bridges (continuous elements like shelf angles and slab edges) and point thermal bridges (discrete penetrations like clip connections), with a new Informative Appendix K providing guidance on identifying and mitigating them across its climate zone tables. It is a widely referenced, technically rigorous framework, and many Canadian architects and engineers use its methodology as a design reference.
It is not, however, the code of record for commercial construction in Manitoba or Saskatchewan. Both provinces enforce the National Energy Code of Canada for Buildings (NECB) 2020 edition as of January 1, 2024, at Tier 1. NECB 2020 addresses the same underlying problem, reducing heat loss through structural thermal bridges, primarily through its continuous insulation provisions and overall thermal transmittance requirements for the building envelope. The compliance path in this region runs through NECB, referencing ASHRAE 90.1's technical methodology (or the parallel research it draws on, much of it from the same building envelope research community) as supporting design guidance rather than as the enforceable standard itself.
Why this distinction matters at the specification stage
A spec that calls out "ASHRAE 90.1 compliance" on a Winnipeg or Regina project is referencing a standard that is not, by itself, the applicable code. The compliance obligation is to NECB 2020 Tier 1. This is worth flagging early with the project's code consultant so the envelope detailing targets the right requirement and the right climate zone table from the start.
Clear-wall vs. whole-wall (effective) R-value
This is the concept both frameworks are built around, and it matters more on a commercial steel-stud wall than almost anywhere else in construction. Clear-wall R-value describes performance through a section of wall with no structural interruptions: cavity insulation between studs, tested or calculated in isolation. Whole-wall, or effective, R-value accounts for every thermal bridge actually present: the studs themselves, shelf angles supporting masonry veneer, parapet cap details, slab edges at each floor line, and window and door framing.
Steel conducts heat roughly 400 times faster than wood, so a steel-stud commercial wall's clear-wall-to-whole-wall gap is typically far larger than the equivalent gap on a wood-framed residential wall (see our residential thermal bridging page for that comparison). A wall cavity insulated to a high clear-wall R-value can still fall well short of code if the structural steel and connection details are not addressed with continuous insulation outboard of the studs.
ASHRAE 90.1-2022
- Scope
- American energy standard; climate zones 0 through 8, with prescriptive tables (5.5-0 through 5.5-8) per zone.
- Thermal bridging treatment
- Explicit linear and point thermal bridge recognition; Informative Appendix K guidance on identification and mitigation.
- Role here
- Widely used technical reference and methodology; not the enforceable code.
NECB 2020
- Scope
- Canadian national energy code; Manitoba and Saskatchewan both at Tier 1 as of January 1, 2024, in NBC Climate Zone 7A.
- Thermal bridging treatment
- Continuous insulation and overall thermal transmittance requirements addressing the same structural bridge concerns.
- Role here
- The enforceable code of record for commercial construction in this region.
Where spray foam fits in commercial envelope detailing
Rigid continuous insulation board handles most of a commercial building's flat wall area efficiently. Spray foam gets specified at the details where rigid board is hardest to install without gaps: slab edges and rim joists at each floor line, parapet caps and the transition where roof insulation meets the wall assembly, balcony and canopy structural connections, and irregular penetrations through the enclosure for mechanical, electrical, and plumbing runs. Its ability to conform to irregular geometry and function as both insulation and a spray-applied air barrier in the same application is the reason it shows up at these specific details even on buildings where the field-of-wall strategy is a different product entirely.
Frequently asked questions
Does ASHRAE 90.1 apply to commercial buildings in Manitoba and Saskatchewan?
Not directly. Commercial construction in Manitoba and Saskatchewan complies with the National Energy Code of Canada for Buildings (NECB) 2020 edition, both provinces at Tier 1 as of January 1, 2024, not the American ASHRAE 90.1 standard. ASHRAE 90.1's thermal bridging methodology, particularly its 2022 edition's explicit treatment of linear and point thermal bridges, is nonetheless widely used as reference technical guidance by architects and engineers working on Canadian projects, since it addresses the same underlying physics NECB's continuous insulation provisions target.
What is the difference between clear-wall and whole-wall (effective) R-value in a commercial assembly?
Clear-wall R-value describes performance through a section of wall with no structural interruptions, essentially a best-case number. Whole-wall, or effective, R-value accounts for every thermal bridge in the actual assembly: studs, shelf angles, parapets, slab edges, and window and door framing. The gap between the two numbers on a steel-stud commercial wall is typically far larger than on a wood-framed residential wall, because steel conducts heat many times faster than wood.
Where does spray foam fit into commercial envelope thermal bridging control?
Spray foam is commonly used as continuous insulation and a spray-applied air barrier at the specific locations where structural thermal bridges are hardest to interrupt with rigid board: slab edges, parapets, balcony and canopy connections, and irregular penetrations through the building enclosure. Its ability to conform to irregular geometry and seal air leakage in the same application is the reason it gets specified at these details even on buildings that primarily use rigid continuous insulation elsewhere.
Detailing an envelope with hard-to-insulate connections?
We work directly with architects and GCs on slab edge, parapet, and penetration details before the spec is finalized.
