If you’ve started looking into spray foam insulation, you’ve probably hit this question early on: “What’s the cost per square foot?”
It seems like a straightforward question. But if you’ve already done some Googling, you’ve probably seen a wide range of numbers. Why such a gap? Because the cost of spray foam really depends on a handful of things—not just the foam itself, but the size of the job, where you live, and what needs to be done before the spraying even begins.
Let’s break it all down so you know what to expect and how to plan your budget wisely—without the guesswork.
There’s no flat rate that fits every job. Here’s what actually influences what you’ll pay:
One thing to keep in mind: if your space is on the smaller side, the price per square foot might actually go up a little. That’s because setup costs don’t change much whether you’re insulating a small nook or an entire attic.
These are the two types of spray foam most commonly used, and they serve different purposes. Naturally, they also come with different price tags.
This type of foam is softer and expands more, which means it’s great for filling tricky spots. It’s also a bit easier on the budget.
Closed-cell is denser and provides more insulation power per inch—but it comes at a higher cost.
In our region—especially around Seattle, Portland, and surrounding towns—you’ll usually find the pricing falls into these ranges:
| Type of Foam | Cost per Sq Ft | Best Use Cases |
|---|---|---|
| Open-Cell | $0.90–$1.50 | Interior walls, attics, soundproofing |
| Closed-Cell | $1.50–$3.00 | Crawlspaces, garages, basements |
A typical homeowner will spend somewhere between $1.25 and $2.75 per square foot. But again—actual costs vary depending on project size and conditions.
Let’s say you’re looking to insulate a 30×40 garage—that’s about 1,200 square feet. If you’re going with closed-cell spray foam at $2.00/sq ft, you’re looking at:
1,200 sq ft × $2.00 = $2,400 total (not counting prep, cleanup, or minor add-ons)
What about an attic? A 1,000-square-foot attic sprayed with open-cell foam might land in the $1,000–$1,500 range.
These ballpark numbers are helpful, but it’s always best to get a quote tailored to your space.
Let’s be real: spray foam costs more up front than fiberglass batts or blown-in cellulose. But you’re not just paying for insulation—you’re paying for performance.
Sure, the initial investment is higher—but over time, many homeowners say the savings make up for it.
There are DIY kits out there for spray foam. And if you’re insulating a van or a shed, they might be okay. But for homes, garages, or anything bigger, the risks often outweigh the savings.
Mistakes are expensive. Uneven application, improper prep, or poor ventilation can all lead to problems down the line—and fixing them can cost more than hiring a pro in the first place.
Instead, ask your contractor how you can help reduce labor time. You might be able to:
| Project Area | Size | Foam Type | Estimated Price Range |
|---|---|---|---|
| Attic | 1,000 sq ft | Open-cell | $1,000 – $1,500 |
| Garage (30×40) | 1,200 sq ft | Closed-cell | $2,000 – $3,600 |
| Crawl Space | 800 sq ft | Closed-cell | $1,600 – $2,400 |
Keep in mind—prices can shift slightly depending on your town, building type, and any site prep that needs to be done.
When we give you a quote, we don’t just show up, spray, and leave. Here’s what’s included:
[Image: Before and after energy bill comparison after spray foam installation]
A few ways to make sure your money is well spent:
Now that you know what goes into the cost per square foot, you’re in a better position to compare quotes and make informed choices. And if you’re looking for insulation that’s built to last, with local pros who know the Pacific Northwest climate inside and out—we’d love to help.
Give us a call or reach out for a free estimate. We’ll walk you through every step and make sure you’re confident before we ever start.
📞 (425) 386-3500
📧 [email protected]
🌐 Visit Cascadia Spray Foam
How much does open-cell foam usually cost per square foot?
Most open-cell foam runs between $0.90 and $1.50 per square foot, depending on how thick you need it.
What makes the cost go up or down?
The type of foam, size of the area, difficulty of access, prep work needed, and whether the job is part of a larger project all play a role.
Is spray foam worth the extra money compared to fiberglass?
If you’re focused on energy efficiency and sealing your home from drafts and moisture, yes—many homeowners find it’s worth the upgrade.
How do I know what my exact price will be?
The only way to get a reliable number is with a professional quote. Every home is different.
Are there any rebates in Washington or Oregon for spray foam?
Yes! Local utility programs sometimes offer cash-back or credit incentives for energy-efficient upgrades. We’re happy to help you check.
Why does spray foam cost more for smaller jobs?
Because setup, labor, and equipment costs are spread across fewer square feet—raising the price per unit.