Spray Foam Insulation Cost Calculator: DIY Kit vs Hiring a Pro
Updated · See the full spray foam insulation cost comparison
Rim joists to a pole barn: DIY kits from $515, a spray foam contractor from $600.
- Pick the job closest to yours. Each size is priced in board feet at the usual depth for that space — 2 inches of closed-cell for rim joists, a garage and a barn; R-21 to R-30 on an attic roof deck.
- On the DIY tab the kits are the whole cost; the safety gear is $115 and non-negotiable. Kits cost about what a pro charges per board foot, so watch how little the gap changes when you untick tools.
- On the Hire a pro tab, tick old-insulation removal and the ignition barrier for an attic, or drywall for a garage — those are the lines a first quote usually leaves out, and they're $750–$5,000.
- The attic shows the pro cheaper, the barn nearly even, the garage about $500 ahead, and rim joists the clear DIY win. Set your hourly rate and see where the break-even falls.
Calculate cost
| Tools to buy or rent | $115 |
|---|---|
| Materials | $8,100 |
| Disposal | $90 |
| DIY cash cost | $8,305 |
| Your time (19 h × $25) | $475 |
| DIY all-in | $8,780 |
A pro is cheaper by $805 — DIY doesn't pay here.
National estimates for planning. Doesn't include the risk-side costs described on the comparison page.
Typical results by job size
Defaults the calculator starts from: commonly owned tools excluded, typical pro price, no add-ons.
| Size | Verdict | DIY | Pro | Your hours | Typical savings | Break-even |
|---|---|---|---|---|---|---|
| Rim joists and small gaps | DIY | $515–$625 | $600–$1,500 | 3–5 hours | $330 (37%) | $83/hour |
| Two-car garage, walls and ceiling | Hire | $2,915–$3,085 | $2,600–$5,000 | 8–14 hours | $500 (14%) | $45/hour |
| 1,500 sq ft attic roof deck | Hire | $8,215–$8,495 | $5,000–$11,000 | 14–24 hours | pro is cheaper | — |
| 30×40 pole barn or shop | Hire | $9,115–$9,415 | $7,000–$13,000 | 20–35 hours | $235 (2%) | $9/hour |
Break-even is what an hour of your time would have to be worth for DIY and hiring to cost the same. Above it, hiring is cheaper all-in. See how these are calculated.
Reading the result
The job you pick applies to both tabs and sets the board feet.
Do it yourself totals two-part closed-cell kits at retail kit pricing scaled to the job — one 200 board-foot kit for rim joists, up to ten 600 board-foot kits for a barn — plus the ignition-barrier coating on the attic and barn, plus the respirator, suit and masking you don’t already own, plus your time at whatever rate you set. Hours are your own, in a respirator: 3–5 for rim joists, 8–14 for a garage, 14–24 for an attic, 20–35 for a barn.
Hire a pro starts from a low, typical or high installed price for that space, then adds what a base quote leaves out: removing old attic insulation, the ignition-barrier coating, drywall as a thermal barrier in a garage or shop, an upgrade from open-cell to closed-cell, sealing attic vents and adding rim joists to a roof-deck job, the combustion-safety and ventilation work a newly sealed attic needs, and the permit. Tick what your job needs and compare.
What neither tab includes: a bad pour. Off-ratio foam from cold tanks, a single thick pass that shrinks from the framing, or overspray on things that can’t be cleaned isn’t a line item — removing failed foam is $1–$3 per board foot plus whatever it’s stuck to. The cost comparison is about which jobs that risk is worth taking; the DIY guide covers the ones where it is.
Frequently asked questions
How do I figure the board feet for my job?
Square feet of surface times inches of depth. A rim joist is the perimeter of the basement in feet times the joist depth in feet (a 2×10 is 0.79 ft), times 2 inches: 150 ft × 0.79 × 2 = about 240 board feet. A garage is the wall area (perimeter × height, minus the door) plus the ceiling, times 2. An attic roof deck is the floor area times 1.15–1.3 for pitch, times 7 for open-cell or 3.5 for closed-cell. Add 15–30% for kit yield loss on the DIY side.
Why does the attic DIY figure come out higher than the pro quote?
Because a kit costs $1.30–$2.00 per board foot and a contractor's installed closed-cell price is $1.30–$2.50 — the material discount a contractor gets on drum foam pays for most of their labor. The attic also includes the ignition-barrier coating code requires over exposed foam, which the DIY math on most sites omits. Untick nothing and the pro is cheaper by about $855; the only way DIY wins an attic is if you value your time at zero and skip the coating.
What do the quote levels mean for spray foam?
Low is open, easy access — a new-construction wall, an empty pole barn — in an inexpensive region, at the minimum code depth. Typical is the national median for that space with standard prep and masking. High is a cramped attic with trusses on 24-inch centers, a coastal metro, or a premium closed-cell system at above-code depth. Removal, barriers, closed-cell upgrades and the combustion-safety work are add-ons on any level.
Sources
- Insulation Workers, Floor, Ceiling, and Wall (SOC 47-2131), Occupational Employment and Wage Statistics , U.S. Bureau of Labor Statistics, 2026-04
- How Much Does Spray Foam Insulation Cost? , HomeGuide, 2026-09
- How Much Does a DIY Spray Foam Insulation Kit Cost? , HomeGuide, 2026-09
- How Much Does Spray Foam Insulation Cost? , Angi, 2026-09
- Types of Insulation , U.S. Department of Energy, 2026-09
- Quick Safety Tips for Spray Polyurethane Foam Users , U.S. Environmental Protection Agency, 2026-09
- International Residential Code, Section R316: Foam Plastic , International Code Council, 2026-09
Figures last reviewed . See how we estimate.