Ecologic Guides · Fire Code
Do you have to cover spray foam with drywall?
Direct answer
In occupied living space, yes. All plastic foam insulation is combustible, and the National Building Code of Canada requires a thermal barrier between the foam and the room. Half-inch (12.7 mm) gypsum drywall is the reference material. Spaces entered only for service, such as crawl spaces and hatch-access attics, are treated differently: a lighter ignition barrier, or in some jurisdictions no covering, may be accepted, and the local building official's interpretation governs. Where drywall is impractical, an intumescent coating tested over spray foam can serve as the protective covering. The closed-cell foam Ecologic installs carries strong fire-test results (ASTM E84 flame spread under 25, Class 1) and still must be covered, because those tests measure how fast flame spreads, not whether the material burns. Every Ecologic quote names the barrier your assembly needs and prices it in.
Sources: NBC 2020 · CUSE TDS 2024 · CCMC 14133-L · GreenBuildingAdvisor
01 The requirement
Why does spray foam have to be covered at all?
Because it burns. Polyurethane foam is an organic plastic, and in a fire it contributes fuel and smoke. This is true of every foam plastic insulation on the market: spray foam, rigid foam board, all of it. The manufacturer of the foam we install puts it plainly on the product's own data sheet:
"All plastic foam insulations are combustible and must be covered by an approved thermal barrier."
CUSE technical data sheet, Grizzly series
The thermal barrier's job is time. In a fire, a layer of gypsum board keeps heat away from the foam long enough for occupants to get out and for the fire to be fought before the foam becomes involved. The code treats this as non-negotiable for spaces where people live and sleep.
It is worth being precise about what the fire tests do and do not say, because contractors sometimes wave good test numbers around as if they ended the conversation. They don't.
| Test | Result | What it measures |
|---|---|---|
| ASTM E84 (closed-cell) | <25 · Class 1 | Surface flame spread |
| CAN/ULC-S102 (closed-cell) | Flame 5 · smoke 130 | Flame spread and smoke developed |
| CAN/ULC-S127 (closed-cell) | 330 | Corner-wall fire exposure |
| CAN/ULC-S102 (open-cell) | Flame 210 · smoke 195 | Flame spread and smoke developed |
These are good numbers, particularly for the closed-cell product. They describe how fast flame travels across the surface under test conditions. They do not make the foam non-combustible, and they do not remove the covering requirement. A Class 1 rating and a thermal barrier requirement coexist on the same data sheet.
02 The standard
What counts as a thermal barrier?
The reference standard is 12.7 mm (1/2-inch) gypsum drywall, mechanically fastened. That is the covering the code names and the one nearly every project uses, because finished walls and ceilings get drywall anyway. If your foam is going into a wall or ceiling that will be finished normally, the thermal barrier requirement costs you nothing extra: the drywall you were already planning satisfies it.
Other materials can qualify where they provide equivalent protection. Lath and plaster, masonry and concrete all do the job. Certain proprietary coatings qualify when they carry fire testing for exactly this use, which is covered in the coatings section below.
What does not qualify: polyethylene sheet, housewrap, thin plywood paneling chosen for looks, or nothing. Foam left exposed in a bedroom, living room or finished basement is a code violation in every Canadian jurisdiction, and it is the single most common deficiency in amateur and cut-rate foam work.
The practical translation
Finished rooms: your normal drywall is the thermal barrier. No extra cost, no decision to make.
Unfinished basements: foamed walls that will stay unfinished need the barrier anyway. Budget for drywall or a tested coating when you budget for the foam.
Rim joists: ask your building official. The rim joist area of an unfinished basement is a frequent point of local interpretation, and the answer varies by municipality.
Service spaces: crawl spaces and hatch-access attics may qualify for lighter protection. Next section.
03 The distinction
Thermal barrier vs ignition barrier: what's the difference?
The distinction is about who is in the space, and how often.
Thermal barrier
Where: living space. Rooms people occupy: bedrooms, living areas, finished basements, and the walls and ceilings that enclose them.
Reference material: 12.7 mm gypsum drywall, or a covering with equivalent tested performance.
Purpose: delay heat from reaching the foam long enough for escape and fire response in the spaces where people sleep and live.
Ignition barrier
Where: spaces entered only to service equipment. Crawl spaces, and attics reached through a hatch rather than a stairway.
Typical materials: mineral-fibre insulation, plywood, sheet metal, or coatings tested for the purpose. Lighter and cheaper than a thermal barrier.
Purpose: protect the foam from casual ignition sources (a work light, a dropped tool spark) in spaces where nobody sleeps.
One honesty note on terminology. "Ignition barrier" is a term from the US model codes. The National Building Code of Canada does not use the phrase, but it draws the same practical line: protection requirements for foamed plastics attach to spaces people occupy, and service spaces are handled differently, with the details resting on how your local authority reads the code. When a Canadian contractor says "ignition barrier," they are borrowing the US word for a distinction Canadian officials also make. The concept travels; the clause numbers don't.
04 The uncomfortable part
Why do the rules feel unclear? Because they are.
You will find contractors who state coverage rules with total confidence, in both directions. Treat that confidence with suspicion. GreenBuildingAdvisor, one of the most careful building-science publications in North America, is blunt about this area of code: the provisions governing thermal and ignition barriers are complicated, poorly written, subject to local interpretation, and unevenly enforced.
That assessment matches what we see in the field. Two municipalities an hour apart can give different answers on the same crawl space. Some inspectors treat a hatch-access attic with a furnace in it as a service space; others note that a furnace means regular visits and ask for more protection. Neither is wrong. The code assigns the call to the authority having jurisdiction, and the AHJ makes it.
What this means for you
The answer to "does my foam need covering?" has two parts, and only one of them is national.
National: occupied living space needs a thermal barrier. Every jurisdiction, no exceptions worth planning around.
Local: crawl spaces, service attics, rim joists in unfinished basements, and outbuildings each depend on your municipality's reading. The reliable move is a phone call to the building office before the foam is sprayed, with the answer noted on the permit or the quote.
A contractor who has already made that call for your municipality, on projects like yours, is worth more than one who quotes the code from memory.
05 Manitoba
The Manitoba answer, space by space
Manitoba builds under NBC 2020 as adopted by the Manitoba Building Code. Here is how the coverage question resolves in practice across the province, with the caveat that your municipal official holds the final word.
| Space | Coverage requirement | Notes |
|---|---|---|
| Occupied living space | Thermal barrier. Cover it. | 12.7 mm drywall is the standard answer and usually already in the plan. |
| Finished or occupied basement | Thermal barrier. Cover it. | Same rule as any living space. |
| Attached garage | Generally yes: drywall. | Shared walls and ceilings typically need gypsum board regardless of the foam. |
| Crawl space, service access only | Ignition-barrier territory | AHJ interpretation varies by municipality. Confirm before spraying. |
| Attic, hatch access for service only | Ignition-barrier territory | Same. Regular equipment access can change the answer. |
| Unoccupied ag and shop buildings | Different rules | Occupancy classification governs; exposed foam or a tested coating is common. Insurers may have their own requirements. |
On farm and shop buildings, one practical warning from prairie experience: the building code and your insurance policy are separate documents. A quonset or machine shed may lawfully carry exposed foam under its occupancy classification while the insurer still requires a protective coating as a condition of the policy. Check both before deciding the coating is optional.
06 The alternative
Intumescent coatings, where drywall is impractical
You cannot hang drywall on the curved interior of a quonset, across an open-web steel deck, or over the irregular surface of a foamed rim joist without building a frame to carry it. For these surfaces the industry uses intumescent coatings: thick, paint-like products that react to fire by swelling into an insulating char, slowing heat from reaching the foam beneath.
Ecologic applies DC 315, a coating tested for use as a protective covering over spray polyurethane foam. It is spray-applied over the cured foam at a specified thickness, and it is the standard answer on steel buildings, exposed ceilings and other assemblies where board coverings don't fit the geometry.
Two cautions. First, acceptance is assembly-specific: a coating is approved over particular foams at particular thicknesses per its fire-test reports, and the building official will want to see that the combination matches the testing. Second, a coating is a fire-protection product, and application thickness matters; this is measured work with a wet-film gauge, documented, and it is a job for the installer, never a can of ordinary paint. Details on our coating work are on the fireproofing and coatings page.
Where coatings are the usual answer
Quonsets and steel-frame shops. Curved and corrugated surfaces that can't take board coverings.
Commercial ceilings and exposed decks. Where the foam and structure stay visible by design.
Service spaces needing an ignition barrier. Where a coating is easier than fitting sheet material around ducts and piping.
Where drywall fits and the room is finished anyway, drywall is usually cheaper. We quote whichever the assembly actually needs.
07 Our practice
What Ecologic does about this on every quote
A spray foam quote that prices the foam and says nothing about the covering is incomplete, and the gap surfaces at the worst time: after the foam is on, when the inspector fails the assembly. Our written quotes handle it in three lines. We name the barrier your assembly needs (drywall by others, drywall by us, or a tested coating), we price our part of it, and where the requirement depends on local interpretation, we confirm with the municipal building official before the quote is final rather than after the spray rig leaves.
If you are comparing quotes, put this question to every bidder: "What does the fire code require over this foam, and where is that in your price?" The answer tells you a lot about the rest of their work.
08 Questions
Thermal barriers, answered
Does spray foam need drywall over it?
In occupied living space, yes. Plastic foam insulation is combustible, and the building code requires a thermal barrier between the foam and the room. Half-inch (12.7 mm) gypsum drywall is the reference material, and it is what nearly every finished wall and ceiling uses anyway. The requirement applies whether the foam is closed-cell or open-cell.
Source: NBC 2020 · CUSE TDS
Can spray foam stay exposed in a crawl space?
Often, but it depends on your local building official. A crawl space entered only to service equipment is treated differently from living space, and a lighter covering, or in some jurisdictions none, may be accepted. Get the answer from your municipality before the foam goes on, and get it in writing. We make that call to the building office part of the quote when the situation is unclear.
What is an ignition barrier?
An ignition barrier is a lighter grade of protection than a thermal barrier, accepted in spaces people enter only for service, such as crawl spaces and attics reached through a hatch. The term comes from the US model codes; Canadian code does not use the word but draws a similar line between occupied rooms and service spaces. Typical materials include mineral fibre, plywood and sheet metal. Which spaces qualify is a local interpretation.
Source: GreenBuildingAdvisor · NBC 2020
Can foam stay exposed in my garage or shop?
In an attached garage, plan on drywall: it is part of your house and usually needs gypsum board on the shared walls and ceiling regardless of the foam. Detached shops and farm buildings are classified differently, and foam is often left exposed or protected with an intumescent coating instead. The building's occupancy classification decides, so confirm with your municipality and your insurer.
What is an intumescent coating?
A thick paint-like coating that swells into an insulating char when exposed to fire, slowing heat from reaching the foam underneath. It is the standard alternative where drywall is impractical, such as curved steel buildings and open ceilings. Ecologic applies DC 315, a coating tested for use as a protective covering over spray polyurethane foam. Acceptance for a specific assembly still rests with the building official.
Source: IFTI DC 315 documentation
Who decides what my project needs?
The authority having jurisdiction: your municipal building official. The code sets the requirement, but the official interprets how it applies to your crawl space, attic or shop, and interpretations differ between municipalities. A contractor who tells you coverage rules without reference to your local office is guessing. When the answer is unclear we ask the official before quoting, and put the answer on the quote.
09 Sources
Primary documents
- National Building Code of Canada 2020 (NRC), as adopted by the Manitoba Building Code: protection requirements for foamed plastics.
- CCMC evaluation listing 14133-L for the closed-cell foam Ecologic installs.
- CUSE Grizzly Gold technical data sheet (2024) and Grizzly 005 technical data sheet (2021): fire-test results and the manufacturer's thermal-barrier statement.
- GreenBuildingAdvisor, "Thermal Barriers and Ignition Barriers for Spray Foam": the code-complexity assessment cited above.
- IFTI DC 315 product documentation: intumescent coating tested for use over spray polyurethane foam.
Planning a project?
Get a written quote with these numbers on it, including the barrier your assembly needs.