Spray foam insulation is one of the most effective ways to insulate a home, and also one of the easiest to get wrong. It costs more than other options, it is very hard to remove, and the quality of the result depends almost entirely on who installs it. For homeowners in Toronto and the Greater Toronto Area, where winters are cold, summers are humid, and much of the housing stock is decades old, it pays to understand both sides before hiring an insulation contractor.
This guide covers how spray foam works, where it performs best, where it causes problems, and what to ask an insulation company before you sign.
What Is Spray Foam Insulation?
Spray foam insulation (spray polyurethane foam, or SPF) is made by mixing two liquid components at the spray gun. The mixture expands on contact, sticks to the surface, and hardens into a foam that insulates and seals air leaks in one step.
There are two main types.
Open-cell spray foam is light, soft, and spongy. It typically provides roughly R-3.5 to R-3.7 per inch, works as an air barrier at adequate thickness, and needs a separate vapour barrier. It is commonly used in interior walls, for sound control, and in some attics.
Closed-cell spray foam is medium density and rigid. It typically provides roughly R-6 per inch, works as an air barrier, and can act as a vapour barrier at the thickness specified by the manufacturer. It is commonly used in basements, rim joists, crawl spaces, cathedral ceilings, and garage ceilings.
R-values vary by product, so always check the manufacturer’s data sheet for the foam being quoted. Natural Resources Canada’s Keeping the Heat In guide is a good plain-language reference for comparing insulation materials.
The Pros of Spray Foam Insulation
1. High R-value in a small space
Closed-cell spray foam delivers more insulating value per inch than batts or loose fill. That matters in places where depth is limited: shallow rafters, cathedral ceilings, rim joists, and basement walls where you do not want to give up floor space. Learn more about how we approach spray foam insulation in these tight areas.
2. Insulation and air sealing in one step
Air leakage is a major source of heat loss in older GTA homes. Spray foam expands into cracks and gaps that batts simply bridge over, so it insulates and air seals at the same time. This is the main reason it outperforms other materials with a similar rated R-value.
3. Moisture resistance for basements and crawl spaces
Closed-cell foam does not absorb water the way fibrous insulation can, and it limits vapour movement. That makes it a strong choice for basement insulation and crawl spaces, where foundation walls are cold and damp for much of the year.
4. It stays where it is put
Spray foam bonds to the surface and does not sag, settle, or shift over time. Closed-cell foam also adds some rigidity to the assembly it is sprayed on.
5. It solves problem areas other products cannot
Rooms above garages, cantilevered floors, and rim joists are common cold spots in GTA homes. These areas are awkward to insulate and air seal with batts. Spray foam is often the most reliable fix.
The Cons of Spray Foam Insulation
1. Higher upfront cost
Spray foam is typically the most expensive insulation option per square foot, and closed-cell costs more than open-cell. In an open attic with plenty of depth, blown-in insulation usually reaches the target R-value for far less money. Spray foam is not automatically the best choice for every part of the house.
2. Results depend heavily on the installer
Spray foam is manufactured on site. If the components are mixed off-ratio, sprayed too thick in one pass, or applied to a surface that is too cold or damp, the foam can cure poorly, shrink, pull away from the framing, or leave a lingering odour. Fixing a bad job is costly. This is the single biggest risk, and it is why choosing the right insulation contractor matters more with foam than with any other insulation.
3. You must leave the home during installation
The chemicals are hazardous while being sprayed and during curing. Occupants and pets need to be out of the home during the work and for the re-entry period the manufacturer specifies, which is often around 24 hours. Installers wear full protective equipment and ventilate the space. The Canadian Urethane Foam Contractors Association (CUFCA) publishes consumer information on what a safe installation looks like.
4. It is very difficult to remove
Spray foam bonds permanently to wood, concrete, and wiring. Future renovations, electrical work, or plumbing repairs in a foamed cavity are harder and more expensive. If you need old material taken out first, see our insulation removal service.
5. It can hide roof leaks
When closed-cell foam is sprayed directly on the underside of a roof deck, a small leak may not show inside the house. Water can sit against the sheathing unnoticed. A sound roof and a proper inspection come first.
6. A tighter home needs proper ventilation
Sealing a leaky house without addressing ventilation can lead to stale air and high indoor humidity. Many homes need an HRV or ERV after a major air sealing upgrade. A good contractor will raise this before the job, not after.
7. It must be covered
Foam plastic insulation is combustible. The Ontario Building Code requires it to be protected by an approved thermal barrier, such as drywall, in most locations inside a home. Exposed foam in a finished basement or attached garage is a code and safety problem.
Is Spray Foam Right for Older GTA Homes?
Often yes, but with conditions. Older Toronto-area houses raise issues that newer subdivisions do not:
- Knob-and-tube wiring must not be buried in insulation. It needs to be assessed and usually replaced first.
- Solid brick walls can be damaged by freeze-thaw cycles if they are insulated from the inside without a moisture assessment.
- Vermiculite or other old attic insulation may need testing and professional removal before any new work.
- Existing moisture problems in a basement must be fixed first. Foam does not cure a leaking foundation.
An honest insulation company will inspect for these issues and tell you when a different material, or a mix of materials, makes more sense. A common approach is spray foam on rim joists and basement walls, with blown-in for the attic insulation.
How to Choose an Insulation Contractor in the GTA
Ask every insulation contractor you are considering these questions:
- Are your installers trained and certified for the specific foam product you use? Ask to see the cards.
- Which product is it, and can I see the data sheet and its CCMC evaluation?
- Does the closed-cell foam meet CAN/ULC-S705.1, and is it installed to CAN/ULC-S705.2?
- What blowing agent does the foam use? Newer products use lower global-warming-potential agents.
- How long do we need to be out of the house, and how will you ventilate?
- What thickness will you spray, and what R-value will that achieve?
- How will the foam be covered to meet the Ontario Building Code?
- Do you carry liability insurance and WSIB coverage?
- What warranty do you offer on labour, and what does the manufacturer cover?
An insulation company that answers these clearly, in writing, is worth more than the lowest quote.
Rebates for Insulation in Ontario
Ontario homeowners may be able to offset part of the cost of insulation upgrades through the Home Renovation Savings Program, offered by Enbridge Gas and Save on Energy. Eligibility, amounts, and end dates change, and some paths require an energy assessment before work begins, so confirm the current rules before you book. Our team can walk you through insulation rebates in Ontario.
Frequently Asked Questions
Is spray foam insulation worth it in Ontario?
It is usually worth it in areas where air sealing, moisture resistance, or limited space matter most, such as rim joists, basements, crawl spaces, and cathedral ceilings. In an open attic, blown-in insulation is often the better value.
How long does spray foam insulation last?
Properly installed spray foam does not settle or sag and is generally expected to last for the life of the building. Check the manufacturer’s warranty for the specific product.
Is spray foam the same as the old UFFI foam?
No. Urea formaldehyde foam insulation (UFFI) was banned in Canada in 1980. Modern spray polyurethane foam is a different product.
Can I install spray foam myself?
Small canned foam is fine for sealing gaps around windows and pipes. Whole-wall or whole-attic spray foam requires professional equipment, training, and safety controls, and should be left to a certified installer.
The Bottom Line
Spray foam insulation is an excellent product in the right place and an expensive mistake in the wrong one. It performs best where space is tight, air leakage is high, or moisture is a concern, and it only performs as well as the crew that installs it. Compare it honestly against other options, ask hard questions, and choose your insulation contractor on qualifications, not price alone.
Ready for a straight answer about your home? Contact our team for an on-site assessment, or learn more about our work as a GTA insulation company.