Rim and band joists
A continuous cold gap around the floor structure, crossed by joists every sixteen inches. Cutting batts to fit each bay is slow and never airtight; foam fills and seals the whole band in one pass.
Service
Spray Foam Insulation in Mississauga
Open-cell and closed-cell polyurethane foam for attics, walls, basements, crawl spaces, garages and commercial building envelopes across Mississauga and the GTA.
- What it does
- Insulates and air seals in a single application
- Two types
- Open-cell and closed-cell, not interchangeable
- Best at
- Irregular framing, rim joists, roof decks, crawl spaces
- Cost driver
- Foam type, thickness, area, access and prep
Spray foam insulation is a polyurethane product applied as a liquid that expands and hardens in place, insulating and air sealing in a single step. NorthStar installs both open-cell and closed-cell foam in Mississauga homes, commercial buildings and industrial facilities, choosing between them based on the assembly rather than a default.
What spray foam insulation is
Spray polyurethane foam arrives on site as two liquid components. They are heated, pressurised and combined at the spray gun, where they react and expand — many times their liquid volume — before setting into a solid cellular plastic. Because it is applied wet and expands into whatever it is sprayed against, it conforms to the shape of the cavity instead of being cut to fit it.
That single property is what separates foam from every other insulation we install. Batts and loose-fill are placed into a space; foam becomes part of it. Where framing is irregular, where pipes and wires cross the cavity, or where a joint would otherwise be impossible to seal neatly, that difference is worth paying for. Where the cavity is a clean, open, regular stud bay, it often is not.
Open-cell vs. closed-cell foam
Both are polyurethane, but they are not interchangeable products with different price tags. They behave differently enough that using the wrong one can create problems rather than solve them.
| Characteristic | Open-cell | Closed-cell |
|---|---|---|
| Cell structure | Cells are broken and interconnected | Cells are sealed and discrete |
| Density | Low — soft and spongy when cured | Higher — rigid and hard when cured |
| Thermal resistance per inch | Lower | Higher |
| Air sealing | Yes, at sufficient thickness | Yes, at sufficient thickness |
| Vapour movement | Permeable — vapour can pass through | Restricts vapour movement at sufficient thickness |
| Structural contribution | None meaningful | Adds rigidity to the assembly |
| Sound | Better at absorbing airborne sound within a cavity | Denser and more rigid; less absorbent |
| Relative cost | Lower per inch installed | Higher per inch installed |
The practical consequence is that closed-cell foam tends to suit places where you want thermal performance in limited depth, resistance to vapour movement, or added rigidity — basement and crawl space walls, rim joists, cantilevered floors, and exterior applications. Open-cell foam tends to suit interior applications where depth is available and vapour needs to be able to move, and where its sound-absorbing behaviour inside a cavity is useful.
We go into this comparison in more depth in our guide to open-cell vs. closed-cell foam.
Air sealing and thermal performance
Insulation slows heat moving through a material. Air sealing stops heated air escaping through gaps in the building — around top plates, at partition walls, through pot light housings, around plumbing stacks and at the attic hatch. These are two different jobs, and in an older GTA house the second is often the more significant of the two.
A well-insulated attic with an unsealed top plate is still losing warm, moist indoor air into the roof space every hour of the heating season. That air takes heat with it and carries moisture that can condense on cold sheathing. Adding more insulation on top of an unsealed ceiling improves the situation, but it does not address the leak.
Spray foam does both at once, which is its main advantage. Applied at sufficient thickness, it forms a continuous layer with no joints to tape and no seams to miss. That is why it is the usual choice for rim joists, where the alternative is cutting and sealing dozens of small rectangles of batt between joists — a job that is slow to do well and easy to do badly.
Moisture and vapour considerations
This is the part of a spray foam job that deserves the most thought, and the part most often skipped in a sales conversation.
An assembly needs to be able to dry — in one direction, the other, or both. Adding a layer that restricts vapour movement changes which directions are available. Closed-cell foam at sufficient thickness restricts vapour movement, which is exactly what you want on the interior of a basement wall, and exactly what you need to think carefully about in a roof or wall assembly that already has a vapour retarder on the other side.
Why we look at the whole assembly before quoting
Foam is not a product you can specify from a photograph of a room. What is on the outside of the sheathing, whether the space is vented, what the existing vapour control looks like and how the building is used all change which foam belongs there and how thick it should be. That is why we assess the space rather than quoting a rate over the phone.
Foam also will not solve a water problem. If a roof leaks, a foundation lets water in, or a bathroom fan vents into the attic instead of outdoors, insulating over it makes the problem harder to see rather than making it go away. Where we find one of those, we will tell you, and we will recommend fixing it before we insulate.
Where we install spray foam
Residential
- Attics — usually at the roof line rather than the attic floor, where the goal is to bring ducts or a finished space inside the insulated envelope
- Basements — closed-cell on foundation walls, where its resistance to vapour movement is the point
- Crawl spaces — walls and rim, to bring the crawl space inside the building envelope
- Rim and band joists — one of the most cost-effective foam applications in any house
- Cantilevered floors — bedrooms over garages, bay windows and overhangs, which are almost always the coldest rooms in the house
- Garage ceilings below living space
- Walls — in renovations where the framing is open, and in additions
Commercial and industrial
- Warehouse and distribution centre envelopes
- Manufacturing and process facilities
- Roof decks and underside of metal roof assemblies
- Block and precast wall interiors
- Mechanical and service rooms
- Cold storage and temperature-controlled space
More on how we handle these on our commercial insulation and industrial insulation pages.
New construction and retrofit
In new construction, foam goes in with open framing, clear access and no existing material to work around — the most straightforward version of the job, and the one we quote from drawings for builders and general contractors. In a retrofit, the variables multiply: what is already there, how much of it has to be removed, how the space is accessed, and what has to be protected while we work.
The installation process
- Assessment. We look at the space, the assembly and the access, and confirm which foam suits and at what thickness.
- Quote. Itemised, covering preparation, any removal, the foam type and thickness, and reinstatement.
- Preparation. Clearing and protecting the area, masking anything that must not be sprayed, isolating the work zone and setting up ventilation. Existing insulation is removed if it is in the way.
- Application. Foam is applied in controlled passes (“lifts”) to the specified thickness. Applying too much in a single pass generates excess heat and gives a poor result, so depth is built up in layers.
- Trimming. Where foam has expanded past the framing — for example in a wall that will be drywalled — it is trimmed back flush.
- Curing and ventilation. The area stays ventilated and unoccupied for the period appropriate to the product and thickness.
- Clean-up and walkthrough. Trimmings and masking removed, and a look over the completed work with you.
Curing and re-entry considerations
Spray foam is a chemical reaction that takes place on site. During application and while the foam cures, the area needs to be ventilated and clear of anyone without appropriate respiratory protection. Our installers work in supplied-air respirators; the building occupants need to be out of the affected area.
Re-entry time varies with the product, the thickness applied and how well the space ventilates. We will tell you the figure that applies to your job before we start, so you can plan around it. We will not give you a single number on a web page, because a number that is right for a thin lift in a well-ventilated warehouse is not right for a deep application in a closed crawl space.
What affects the cost
We do not publish per-square-foot pricing, for the same reason we do not quote over the phone: the number would be wrong often enough to be useless. What we can be specific about is what moves it.
- Foam type. Closed-cell costs more per inch installed than open-cell.
- Thickness. Driven by the performance the assembly needs, and it is the largest single variable.
- Area. Larger continuous areas are more efficient to spray than the same total area broken into small awkward pieces.
- Access. A crawl space you enter on your stomach costs more to work in than an open basement. Height, hoarding and lift requirements do the same on commercial sites.
- Preparation. Masking, protection and isolating the work zone.
- Existing insulation. If it has to come out first, that is a separate scope with its own cost.
- New build vs. retrofit. Open framing is faster and cheaper to work with than a finished building.
- Scheduling constraints. Occupied buildings, after-hours work and phased access all add time.
Our guide to spray foam insulation cost in Mississauga walks through each of these in more detail.
Benefits and limitations
What spray foam does well
- Insulates and air seals in one application
- Conforms to irregular shapes and awkward cavities
- High thermal resistance per inch in its closed-cell form, where depth is limited
- Does not settle or slump over time the way loose-fill can
- Adds rigidity to an assembly (closed-cell)
- Restricts vapour movement where that is what the assembly needs (closed-cell)
Where it is the wrong choice
- In a regular, accessible, open stud cavity, where properly fitted fibreglass batts achieve the same specified performance for much less
- On a straightforward attic floor that simply needs more depth — that is a blown-in job
- Over wet, dirty or unstable substrates, where it cannot bond properly
- As a substitute for fixing a leak, a drainage problem or a misdirected exhaust fan
- In an assembly where restricting vapour movement on that side would trap moisture
- Where the disruption of vacating the space cannot be accommodated
An honest note on where foam gets oversold
Spray foam is frequently marketed as the right answer for every building. It is not. It is an excellent product with a specific set of strengths, and a contractor who recommends it for every assembly regardless of what is behind the drywall is selling a product rather than solving a problem. We would rather quote you batts and keep the relationship.
Frequently asked questions
Is spray foam better than fibreglass insulation?
Not universally. Spray foam air seals as well as insulates, performs well in irregular spaces, and gives more thermal resistance per inch in its closed-cell form. Fibreglass batts cost far less and perform exactly as specified in a regular, accessible stud cavity that has been air sealed separately. The better product is the one that suits the assembly and the budget, and in many houses that is fibreglass.
How long does spray foam last?
Cured polyurethane foam is a stable, rigid or semi-rigid plastic that is not expected to slump, settle or biodegrade in a normal building assembly, so it does not need topping up the way loose-fill can. That said, it can be damaged by prolonged water intrusion, by UV exposure if left uncovered, or by physical disturbance during later renovation work.
Does spray foam need to be covered?
In most occupied spaces, yes. Sprayed polyurethane foam generally requires a covering such as drywall, or another approved thermal barrier or ignition barrier, depending on the space and how it is used. The requirement depends on the specific assembly and occupancy, so we confirm what applies to your project before quoting it.
Can spray foam be installed over existing insulation?
Usually it should not be. Foam needs to bond to a clean, dry, stable substrate. Spraying over old fibreglass traps it against the sheathing and gives an unreliable bond. Where existing insulation is in the way, it comes out first — see attic insulation removal.
How long before I can be back in the space?
Spray foam is applied by trained installers wearing supplied-air respiratory protection, and the area is ventilated and kept clear of other people during application and for a period afterwards while the foam cures. The exact re-entry time depends on the product used, the thickness applied and how well the space ventilates, so we confirm it for your specific job rather than quoting a single figure.
Do you spray foam in occupied homes?
Yes, with the work area isolated and ventilated, and with the occupants out of that area for the application and cure period. For larger jobs we plan the sequencing with you in advance so you know which parts of the building are unavailable and when.
Applications
Where foam earns its price
Foam costs more per unit of thickness than anything else we install. These are the places where that premium buys something a cheaper material genuinely cannot deliver.
Cantilevered floors
Bedrooms over garages and floors projecting past the foundation are exposed on five sides. Foam seals the cavity closed rather than leaving a route for outside air to circulate under the floor.
Crawl spaces
Where the decision is made to bring the crawl space inside the building envelope, closed-cell on the walls and rim controls both heat loss and vapour movement from the ground.
Roof lines and cathedral ceilings
When ducts run through the attic, or the attic becomes living space, foaming the underside of the roof deck moves the insulated boundary up to the roof instead of the ceiling.
Renovations and additions
Old framing is rarely square, and a renovation exposes cavities that will be unreachable once drywall goes up. Foam conforms to what is actually there rather than what the plan assumed.
Commercial and industrial envelopes
Metal roof decks, block walls and large uninterrupted surfaces where a sprayed product covers ground quickly and handles the transitions that batts leave open.
Suitability
Where spray foam insulation does and does not belong
Every material on this site is the wrong answer somewhere. Knowing which side of this split your project sits on is worth more than any specification sheet.
A good fit when
- Cavities that are irregular, obstructed or awkward to reach
- Assemblies where air sealing and insulation have to happen in one step
- Depth-limited spaces that need maximum resistance per inch
- Surfaces where vapour movement has to be controlled as well as heat
Probably the wrong choice when
- Clean, open, regularly spaced stud bays where a batt fits properly
- Attic floors that simply need more depth over a sealed ceiling
- Assemblies that need to stay vapour-open in both directions
- Anywhere the budget is better spent on air sealing the obvious leaks first
If your project sits on the right-hand list, say so when you call and we will point you at the service that actually fits — including the cheaper one. Here is how this work relates to everything else we do.
Foam is one of six things we install, and it is the right answer less often than a foam contractor would like to admit. Where an attic floor is open and simply shallow, blown-in loose fill builds depth for a fraction of the price, and where a stud bay is square and accessible a properly fitted fibreglass batt does the same job for less again. If what is already up there is wet or contaminated, the honest first step is taking it out rather than spraying over it.
Foam also gets confused with fire protection, which it is not — spray polyurethane is a combustible plastic, and applied fire protection is an entirely separate discipline. Its sound-absorbing quality is real but partial, so a genuine noise complaint belongs with sound-control work instead. Two guides go deeper than this page does: open-cell versus closed-cell and what actually drives the cost.
Most of our foam work is residential — houses, semis and townhouses around Mississauga — but the same crew sprays warehouse and plant envelopes and works to specification for builders and general contractors. We spray across the western GTA, including Brampton and Etobicoke. Tell us about the assembly and we will come and look at it before quoting.
Before you commit
What goes wrong with spray foam
Foam is unforgiving in a way batts are not: once it has cured, a mistake is a demolition job rather than a re-fit. These are the failures worth knowing about before anyone sprays.
The wrong foam for the assembly
Closed-cell against a surface that needed to dry inward, or open-cell where vapour control was required, creates a moisture problem that will not show up for a season or two.
Sprayed too thick in one pass
Foam generates heat as it cures. Applied in lifts that are too deep it can scorch internally, which affects both performance and adhesion. Correct lift thickness is a product specification, not a preference.
Substrate not ready
Foam bonds to what it is sprayed against. Dust, frost, damp sheathing or loose paint all compromise adhesion, and none of it can be corrected after the fact.
Re-entry rushed
Curing and ventilation times are set by the manufacturer for the product being used. Compressing them to suit a schedule is the single most common corner cut in this trade.
Also from NorthStar
Other services that come up alongside this one
Blown-In Attic Insulation
Loose-fill fibreglass or cellulose blown across an attic floor to an even, measured depth. The usual choice for topping up an under-insulated attic.
Attic Insulation Removal
Vacuum removal of old, damaged or contaminated attic insulation, with containment and disposal, so the attic can be air sealed and re-insulated properly.
Fibreglass Batt Insulation
Pre-cut fibreglass batts friction-fit into walls, ceilings, basements and garages. Cost-effective and dependable when it is cut and fitted correctly.
Related services and reading
Get a quote for spray foam insulation
Tell us about the space — what it is, roughly how big, and what you are trying to solve. We will assess it and quote the foam type and thickness that actually suits the assembly.