Questions About Spray Foam Insulation

It stops air moving. Batt and loose fill resist heat travelling through them, which is useful, but neither one closes the gaps around and behind them. Spray foam insulation is applied wet, expands into the actual shape of the opening and hardens there, so it becomes the air barrier and the insulation in one pass. On a coastal site that second job is worth more than the first, because the air moving through those gaps is carrying moisture with it.

Closed cell spray foam insulation for anything below grade, in contact with the ground, in a thin assembly like a rim joist, or under a roof deck. Open cell spray foam insulation for interior partitions, between storeys, and for deep cavities well inside the heated envelope where the job is sound or bulk fill rather than vapour control. The deciding line is usually vapour: closed cell is its own vapour barrier at sufficient thickness and open cell is not one at any thickness.

Not over batt or loose fill. Spray foam insulation has to bond to a solid substrate, and anything with air in it is not one, so the old insulation comes out first. On clean masonry, a bare roof deck or open framing it goes straight on.

A normal spray foam insulation install has a noticeable smell during spraying and for the re-entry window afterwards, which we give you in writing beforehand. A smell that is still there weeks or months later is not normal. It indicates off-ratio spray foam insulation, meaning the components did not mix correctly, and that material has to be removed mechanically rather than aired out or sealed over.

Wherever people spend time, yes. Spray foam insulation burns, so it needs a thermal barrier in front of it, and half inch gypsum board is what that normally means. Attics and crawl spaces are the exception, because nobody occupies them; a tested ignition barrier of lesser thickness generally does the job there. The quote states which requirement applies to your building and who is installing it.

Yes. The Total Home Energy Savings Program pays per square foot of insulation added, with attics running from about $0.40 to $0.85 a square foot and basement and crawl space walls from about $1.00 to $2.00, depending on the R-value added. You need an energy evaluation by an approved energy advisor before the work starts and another afterwards, and work done before the first evaluation does not qualify. Amounts and rules change, so confirm current terms with the program rather than with a contractor.

Most residential spray foam insulation jobs are a single day. Preparation, masking and getting the space and the insulation to working temperature take a real part of that, and the spraying itself is fast. Large or awkward spaces run to two days. Commercial roof decks depend more on lift access than on area.

Sealing a building changes how it has to be ventilated, and that is a genuine consideration rather than an objection. A building sealed with spray foam insulation needs deliberate mechanical ventilation instead of relying on leaks. The advantage is that you control it and can filter it, rather than pulling humid coastal air through the wall assembly on its way in. We raise it when a job is going to take a building into that territory.