Open-cell foam expands to fill irregular cavities, gaps, and odd framing that blown-in or batts leave partially sealed. It is lighter and generally less costly per square foot than closed-cell, and it is a strong fit for interior walls, attic undersides, and areas where a full vapour barrier is not required. It does not resist moisture the way closed-cell does, so we match the assembly to the material rather than defaulting to one option everywhere.
Closed-cell foam has a denser cell structure, a higher R-value per inch than open-cell, and acts as its own vapour barrier once cured. That makes it the better choice for basement rim joists, additions with limited cavity depth, and exterior applications where moisture control matters as much as thermal resistance. It costs more per square foot than open-cell, which is why we scope the assembly first rather than quoting foam as a single flat price.
Spray foam earns its cost in specific spots, not as a blanket replacement for blown-in or batt insulation.
The most common spray foam application in Ottawa basements. Angled ceilings, cathedral ceilings, and other tight or odd-shaped cavities.
Tight or irregular cavities in additions and renovated spaces where a single continuous layer matters most.
Spaces where a vapour barrier and insulation need to be one continuous layer.
We identify which areas call for open-cell versus closed-cell based on moisture exposure and cavity depth.
Surfaces are cleared and protected, and surrounding areas masked off before spraying.
Foam is sprayed in controlled lifts to the specified thickness for the assembly.
Foam is left to cure, then trimmed flush where it needs to sit behind drywall or other finishes.
These are the sourced per-square-foot ranges. Exact pricing depends on cavity depth, access, and how much surface prep the space needs.
$2-$4 per sq ft
Expands into irregular gaps
Lighter, lower cost per sq ft
Good where full vapour barrier is not required
$4-$7 per sq ft
Higher R-value per inch
Acts as its own vapour barrier
Best for rim joists and limited cavity depth
Ottawa Insulation Experts provides professional spray foam insulation throughout Ottawa, Ontario. This service is for rim joists, additions, and irregular cavities where blown-in or batt insulation cannot seal properly, since spray foam expands to fill gaps and air-seal in a single application. We install both open-cell and closed-cell foam, matched to the assembly rather than applied as a one-size-fits-all product. Closed-cell suits moisture-exposed or space-limited spots like basement rim joists, while open-cell fits interior cavities where a full vapour barrier is not required.
It depends on the assembly. Closed-cell is the better fit where moisture exposure or limited cavity depth is a factor, like rim joists. Open-cell suits interior cavities without those concerns. We recommend the right one during the on-site assessment.
Closed-cell foam acts as its own vapour barrier once cured. Open-cell does not, so a separate vapour barrier may still be needed depending on the assembly.
In most cases yes, as long as the rim joist is dry and free of existing insulation that would trap moisture. We check this during the assessment before quoting.
No. While rim joists are the most common application, we also use spray foam in additions, cathedral ceilings, garages, and other irregular cavities where blown-in or batts cannot seal well.
Foam cures within a set period after application before it can be trimmed or covered, which we account for when scheduling the job.
Almost every removal case traces back to improper installation, not the material itself: foam applied over a wet or contaminated surface, mixed at the wrong ratio, or sprayed where it blocks ventilation and traps moisture against roof sheathing or framing. Correctly installed foam on a dry, prepared surface with the right ventilation plan does not carry these risks. We check moisture, ventilation, and surface condition before quoting any spray foam job.
Yes, when it is applied to the right part of the assembly with a proper ventilation plan. The risk with attic spray foam is sealing off roof ventilation that the assembly needs, which can trap moisture against the roof deck. We assess whether foam belongs on the attic floor or the underside of the roof deck for your specific attic before recommending it.