Guides
Plain-language guides to spray foam insulation. Every figure names its source and the date we checked it.
Foam types
Open-cell and closed-cell spray foam, what density means, and how to read a product data sheet.
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Open Cell Spray Foam Insulation: R-Value, Benefits & Uses
Learn how open cell spray foam insulation works, its R-value, cost, benefits, drawbacks and best applications before choosing insulation for your home.
Read the guide Updated October 19, 2026 -
Closed Cell Spray Foam Insulation: R-Value, Cost & Uses
Closed cell spray foam delivers high R-value per inch and strong air sealing. Compare costs, thickness, moisture control, best uses and drawbacks.
Read the guide Updated October 19, 2026 -
Open Cell vs Closed Cell Spray Foam: Which Is Better?
Open cell vs closed cell spray foam compared: R-value, installed cost, moisture resistance, attic use and which type is right for your home.
Read the guide Updated October 19, 2026 -
2 lb vs 0.5 lb Spray Foam: What's the Difference?
Compare 2 lb vs 0.5 lb spray foam insulation by R-value, moisture control, thickness, cost and application. See which density fits your building.
Read the guide Updated October 19, 2026
Costs & calculator
Published national cost ranges with their sources, how contractors price by the board foot, and an estimate calculator.
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How Much Does Spray Foam Insulation Cost in 2026?
Spray foam insulation costs about $1.50–$5 per treated square foot installed. Compare open- and closed-cell prices, board-foot math and worked estimates.
Read the guide Updated October 19, 2026 -
Spray Foam Insulation Cost per Square Foot
Spray foam insulation costs about $1.50–$5 per treated square foot installed. Compare open- and closed-cell pricing, thickness math and worked estimates.
Read the guide Updated October 19, 2026 -
Spray Foam Insulation Cost per Board Foot
Spray foam costs about $0.60–$1.60 per board foot open-cell and $1.30–$3.10 closed-cell, installed. Learn the board-foot formula and compare quotes.
Read the guide Updated October 19, 2026 -
Spray Foam Insulation Cost Calculator
Free spray foam insulation cost calculator. Enter area, thickness and foam type to estimate board feet, installed cost range and approximate R-value.
Read the guide Updated October 19, 2026 -
Open Cell Spray Foam Cost: Prices, Thickness & Examples
Open cell spray foam costs about $0.60–$1.60 per board foot installed. Compare wall and attic estimates, thickness, R-value and contractor quotes.
Read the guide Updated October 19, 2026 -
Closed Cell Spray Foam Cost: Prices, Thickness & Examples
Closed cell spray foam costs about $1.30–$3.10 per board foot installed. See costs by thickness, project size, application and R-value.
Read the guide Updated October 19, 2026 -
Open Cell vs Closed Cell Spray Foam Cost
Compare open-cell vs closed-cell spray foam costs per board foot, per square foot and at equal R-value, with worked prices and the math behind them.
Read the guide Updated October 19, 2026
Where spray foam goes
Attics and roof decks, crawl spaces, basement walls, rim joists, exterior walls and barndominiums.
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Attic Spray Foam Insulation: Cost, Foam Types & Roof Deck Risks
Attic spray foam explained: attic floor vs roof deck, open- vs closed-cell, thickness, moisture risks, cost per board foot and what to ask before you hire.
Read the guide Updated October 19, 2026 -
Spray Foam Roof Deck Insulation: How It Works, Costs & Risks
How spray foam under the roof deck works: unvented attic rules, open- vs closed-cell by climate, moisture and leak risks, thickness and retrofit planning.
Read the guide Updated October 19, 2026 -
Vented vs Unvented Attic: Which Is Better With Spray Foam?
Vented vs unvented attics compared: how each works, when each is better, moisture risk, energy, cost and what converting an existing attic involves.
Read the guide Updated October 19, 2026 -
Crawl Space Spray Foam Insulation: Where to Apply It, Cost & Moisture Risks
Crawl space spray foam explained: walls of a sealed crawl space vs the floor above a vented one, closed- vs open-cell, moisture, thickness and cost.
Read the guide Updated October 19, 2026 -
Spray Foam Basement Walls: Best Foam, Cost & Moisture Risks
Can you spray foam basement walls? Closed- vs open-cell on concrete, moisture first, thickness, thermal barrier, cost per board foot and finished walls.
Read the guide Updated October 19, 2026 -
Spray Foam Rim Joists: Cost, Thickness & How to Insulate Them
How to insulate rim joists with spray foam: closed- vs open-cell, air-barrier thickness, where to spray, condensation risk, fire rules, DIY and cost.
Read the guide Updated October 19, 2026 -
Spray Foam Insulation for Exterior Walls: Types, Cost & Installation
Spray foam in exterior walls: open- vs closed-cell in 2x4 and 2x6 walls, new construction vs retrofit, moisture and vapor control, and how to specify the job.
Read the guide Updated October 19, 2026 -
Barndominium Spray Foam Insulation: Best Type, Cost & Condensation Control
Barndominium spray foam guide: closed- vs open-cell on metal panels, condensation and thermal bridges, living vs shop zones, thickness and cost.
Read the guide Updated October 19, 2026
Spray foam vs other insulation
How spray foam compares with fiberglass, blown-in, cellulose and mineral wool, and when the other material wins.
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Spray Foam vs Fiberglass Insulation: Which Is Better for Your Home?
Spray foam vs fiberglass compared: installed cost, R-value per inch, air sealing, attics, walls, moisture, safety and when each one is worth the money.
Read the guide Updated October 19, 2026 -
Spray Foam vs Blown-In Insulation: Which Is Better for Your Home?
Spray foam vs blown-in fiberglass and cellulose: cost, R-value, air sealing, attic floor vs roof deck, hybrids and which saves more for your attic.
Read the guide Updated October 19, 2026 -
Spray Foam vs Cellulose Insulation: Which Is Better for Your Home?
Spray foam vs cellulose compared: cost, R-value, air sealing, attic floors, dense-pack wall retrofits, moisture, fire and which is better where.
Read the guide Updated October 19, 2026 -
Spray Foam vs Mineral Wool Insulation: Cost, R-Value & Which Is Better?
Spray foam vs mineral wool (Rockwool) compared: cost, R-value, fire resistance, sound, air sealing, moisture and which fits walls, attics and rim joists.
Read the guide Updated October 19, 2026
Problems & safety
Off-gassing, odor, mold and moisture, installation defects, and what the EPA and OSHA say about safety.
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Spray Foam Insulation Problems: 12 Warning Signs, Causes & What to Do
Common spray foam insulation problems: odors, poor cure, shrinkage, missed coverage, moisture and mold, hidden roof leaks, code defects, and what to do.
Read the guide Updated October 19, 2026 -
Spray Foam Off-Gassing: How Long Does It Last and What If It Smells?
Spray foam off-gassing explained: what is released, curing vs re-entry, why odors persist, air testing limits and what to do if the smell lingers.
Read the guide Updated October 19, 2026 -
Is Spray Foam Insulation Safe? Health Risks, Curing & Precautions
Is spray foam insulation safe? Isocyanates, installation fumes, curing and re-entry, fire safety, children and pets, and what to ask the installer.
Read the guide Updated October 19, 2026 -
Spray Foam Insulation and Mold: Can It Cause, Prevent or Hide Mold?
Can spray foam cause mold? How moisture, roof leaks, crawl spaces and closed- vs open-cell foam affect mold risk, warning signs and what to do.
Read the guide Updated October 19, 2026
DIY spray foam
What DIY kits can and cannot do, and when to hire a professional.
Hiring a contractor
How to choose a spray foam contractor and the questions to ask before you sign.
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How to Choose a Spray Foam Contractor
How to choose a spray foam contractor: a 12-point scorecard covering licenses, insurance, crew, product, moisture survey, safety plan, warranty and price.
Read the guide Updated October 19, 2026 -
Questions to Ask a Spray Foam Contractor
25 questions to ask a spray foam contractor, the evidence to request for each, weak vs strong answers, and a copy-and-send quote request.
Read the guide Updated October 19, 2026 -
Insulation Contractors Near Me
Find insulation contractors near you: match the specialist to the job (attic, walls, rim joists, basement), compare materials and bids, and spot red flags.
Read the guide Updated October 19, 2026 -
Attic Insulation Contractors
Attic insulation contractors: vented attic floor vs unvented roofline, who should inspect first, what each specialist should document, and how to compare bids.
Read the guide Updated October 19, 2026
Codes & technical
The building code sections that apply to spray foam: thermal and ignition barriers, unvented attics and crawl spaces.