What Spray Foam Costs in Maine

Most insulation contractors will not put a price on a website. We understand why - every job is different, and a number on a page can be quoted back at you eighteen months later. But "how much does spray foam cost" is the question everybody asks first, and refusing to answer it is not much of an answer.

So here is ours, along with the part that usually gets left out.

The unit is a board foot, not a square foot

This is where nearly every confusing insulation quote comes from. A board foot is one foot by one foot, one inch thick. It is a unit of volume, not area.

That matters because foam is priced by how much of it goes in, and how much goes in depends on how thick we spray it. Double the thickness and you have doubled the material, the time and the cost - over the exact same square footage.

And it is the square footage of the surface, not the house

The second thing that trips people up. When we say square feet, we mean the area of the wall or the roof deck we are actually spraying - not the floor area of the house.

Those are very different numbers, and they are not related in any tidy way. A long single-story ranch and a compact two-story of the same floor area have very different amounts of exterior wall. A steep cathedral ceiling has far more roof deck than the room below it has floor. So "it is a 1,500 square foot house" does not tell us what we need to know.

If it is any comfort, this catches people in our other trade too. Drywall is priced off how much board the job takes, not the size of the room - same trap, different material. More on the drywall side.

Running the numbers yourself

The arithmetic is genuinely simple once the unit makes sense. Multiply $1.50 by the number of inches. That gives you the cost per square foot of surface at that thickness. These are the thicknesses most jobs land on:

Typical closed-cell thickness by assembly

Where it goes	Thickness
WallsR-21, the wall target we build to most often	3 in
Roof or ceilingThe thickness most of our roof jobs actually land on	5 in
Roof, to an R-60 targetWhat a full R-60 roof spec asks for	8 in

Then multiply by the square footage of wall or roof you are covering. That is your material-and-labor ballpark, and it will get you close enough to decide whether the project is worth a real conversation.

Your code official has the final say on what your project has to hit, and requirements have tightened in recent years. Worth confirming your target before you plan a budget around any thickness.

What moves the number

• Thickness - the biggest factor by a distance, as above.
• Closed-cell or open-cell - open-cell costs less per inch but gives you roughly half the R-value per inch, so the comparison is never like for like. The full comparison.
• Access - an open new-construction wall we can walk up to is the cheap case. A crawl space we have to belly-crawl through, working overhead, costs more per foot for the same foam.
• How cut-up the space is - dormers, knee walls, odd bays and tight rafter runs are slower than a long clean wall.
• Whether we are doing your drywall too - if we are, that is one crew and one schedule rather than two.

Why we still will not quote you over the phone

Everything above is our rate. It is not your total, and we would be doing you no favors by pretending otherwise.

A number given blind is one of two things: padded to cover everything we cannot see, or too low to honor once we get there. Neither is much use to you. The rate is public because you are entitled to know how we price. The total needs somebody to look at the building.