Spray foam has a temperature range. Alberta's design cold is below all of it.

These come from Canadian technical data sheets. Manufacturers formulate seasonal grades precisely because the reaction is temperature-sensitive; a summer grade sprayed onto a cold substrate is not the same material as a winter grade sprayed onto the same substrate.

Temperature is the criterion everyone quotes. The ones that actually stop a winter job more often are moisture-related, because a warm enclosure over a cold building is a condensation machine if it is managed carelessly.

• Substrate above dew point. Huntsman specifies the substrate must be at least 5 °C above dew point, with best processing results below 80% ambient humidity. Elastochem specifies more than 3 °C above dew point and ambient humidity below 80%. Different manufacturers, same principle. Heatlok Soya HP TDS · Insulthane Extreme guide
• Free of dew and frost. The substrate must be free of moisture, grease, oil and solvents. Frost on a joist is not a cosmetic problem; it is a bond-line problem. Heatlok Soya HP TDS
• Substrate moisture content ≤ 19%. Above that, the substrate is not ready regardless of its temperature. Heatlok Soya HP TDS
• The code requires a clean, dry, frost-free substrate for spray-applied insulation, in the Article 9.25.2.3 family, and requires the installation itself to be carried out in accordance with CAN/ULC-S705.2 under Article 9.25.2.5. NBC(AE) · 9.25.2.3 / 9.25.2.5

Spray foam generates heat as it cures. The pass-thickness limit exists to keep the core of the foam below the temperature at which it can scorch or ignite, and it is the single most consequential application rule on the list.

The high-lift exception is worth understanding rather than generalising from. It is a product-specific evaluation, listed under a CCMC Technical Guide precisely because it departs from the standard’s 50 mm rule. It is not permission to spray any product thick.

This matters commercially because the widespread assumption runs the other way — that winter work is inherently second-rate. The measured data does not support that, provided the substrate was in range. Which brings the whole question back to enclosure and heat, and to whether the substrate temperature was recorded.

The failure modes below are industry practice and standards commentary rather than published test results — they are described here as failure modes, not quantified.

• Off-ratio mix and poor cure. The chemistry is temperature-dependent on both sides.
• Poor adhesion and delamination from a cold or frosted substrate — the bond line is where cold shows up first.
• Shrinkage and dimensional instability as the foam cures against a cold surface.
• Reduced yield. Denser foam, fewer board feet per set: the job costs more and delivers less resistance for the same chemical. This is the one a client feels in the invoice rather than in the wall.

The related risk in the other direction is odour. A lingering fishy, amine or sweet smell after cure is the signature of off-ratio spraying, poor mixing, a contaminated or wet substrate, or over-thick lifts — not of foam in general. An independent indoor air quality investigator’s published base rate is that fewer than one in two hundred spray foam jobs is associated with odour problems. May Indoor Air Investigations

All of the above is checkable after the fact, because the application standard requires the job to be documented as it is sprayed. Ask for the paperwork rather than for reassurance.

• The Daily Work Record. Required at every job, at every chemical lot change, and every 8 hours of continued spraying under the site quality assurance programmes. A municipal DWR form shows the fields actually recorded: substrate temperature, ambient temperature, wind, density test result, passes and thickness, and chemical lot numbers. District of Lake Country DWR form
• Daily on-site tests. Adhesion, cohesion and core density, run with an approved kit and documented, available to the customer and to the authority having jurisdiction. CUFCA quality assurance programme
• The product and its grade. Seasonal grades are distinct products with distinct ranges. Which grade, and what the substrate temperature was when it went on, is a single question with a documented answer.
• The certification behind the crew. The code’s hook is Article 9.25.2.5 pointing at CAN/ULC-S705.2, which is what requires the certified installer, the licensed contractor and the daily records. Four programmes are recognised by CCMC — CUFCA, Caliber, BPC and UFC — and each manufacturer designates one for its product, so the right question is “which programme does this product’s manufacturer designate, and do the cards match?” rather than naming a body in advance.

• No clause numbers are quoted from CAN/ULC-S705.2. The standard’s text is paywalled. The substrate and pass criteria above are as reflected in manufacturers’ Canadian data sheets and CCMC evaluations, which is a legitimate basis for stating them — and not a legitimate basis for quoting a clause number. The one section safely citable is 4.3.4, on installer certification, because Alberta’s adopted RDH report cites it explicitly.
• Tenting and temporary heat are standard trade practice, not a requirement written into a standard. What is written down is the substrate range, the frost-free requirement and the dew-point rule. Enclosure and heat are how those get met in an Alberta January — described here as practice, because that is what they are.
• This page describes published product limits and code requirements. It makes no statement about any particular contractor’s equipment, scheduling or capability.

If the assembly in question is a roof, the substrate criteria carry extra weight: Alberta’s unvented-roof variance is conditional on the S705.2 criteria being followed, which is set out on the unvented roofs page.