The average cost of spray foam insulation in the Seattle area ranges between $2.50 and $7.00 per square foot, depending on the type (open-cell vs. closed-cell), project complexity, and area covered. For a typical 2,000 sq. ft. home, full insulation can run between $5,000 and $14,000—but the long-term savings on energy bills often justify the investment.
At Cascadia Spray Foam of Seattle, we specialize in energy-efficient spray foam applications designed to lower your utility bills and boost home comfort year-round. This guide lays out everything you need to know about spray foam costs—from material comparisons to bonus savings tips—so you can make a smart, informed decision.
Spray foam comes in two main forms, each with distinct pricing and performance characteristics.
| Spray Foam Type | Cost/Sq. Ft. (Installed) | R-Value/Inch | Key Benefits | Best For |
|---|---|---|---|---|
| Open-Cell Foam | $1.00 – $2.50 | 3.5 – 3.8 | Soundproofing, flexibility, lower cost | Interior walls, attics |
| Closed-Cell Foam | $2.50 – $7.00 | 6.0 – 7.0 | High insulation value, moisture barrier | Crawlspaces, basements, exteriors |
Bonus Tip: If your goal is maximum energy savings, closed-cell foam—while pricier—is the better long-term investment due to its higher R-value and air/moisture sealing properties.
Several factors influence the final quote for spray foam installation:
Bonus Tip: Combine multiple insulation areas into one job (e.g., attic + crawlspace) to reduce per-square-foot costs through labor efficiency.
R-value measures how resistant insulation is to heat flow—the higher, the better. Seattle falls into Climate Zone 4, where moderate winters and cool summers still demand strong insulation performance for energy efficiency.
| Area | Recommended R-Value | Suggested Spray Foam Type |
|---|---|---|
| Attic (roof deck) | R-38 to R-49 | Closed-cell |
| Exterior walls | R-13 to R-21 | Open-cell or closed-cell |
| Floors over unheated areas | R-19 to R-25 | Closed-cell |
| Crawlspaces | R-13 to R-19 | Closed-cell |
| Project Type | Square Footage | Foam Type | Estimated Cost Range |
|---|---|---|---|
| Attic retrofit | 1,000 sq. ft. | Closed-cell | $4,000 – $6,000 |
| Wall insulation (new build) | 1,500 sq. ft. | Open-cell | $3,000 – $4,500 |
| Full home (2,000 sq. ft.) | 2,000 sq. ft. | Mix of both | $7,000 – $11,000 |
Seattle Insight: Thanks to rising energy rates in Washington, many local homeowners recover their investment within 3–5 years through energy savings alone.
With spray foam insulation, you’re not just insulating—you’re investing in long-term comfort and cost control. Whether you’re planning a new build or retrofitting an older home, Cascadia Spray Foam of Seattle can help you identify the smartest path forward for your budget and needs.
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Upfront, yes. But it provides superior air sealing and energy savings, often making it more cost-effective.
Start with your attic or crawlspace—areas that lose energy.
It depends on your goals. For moisture-prone or exterior spaces, closed-cell is ideal. S
Absolutely. Many customers tackle one section at a time based on budget and urgency.
Yes, and that’s a good thing if managed properly. We address this during planning.