Understand R-value and what insulation really costs. Then get matched, free, with installers you can trust.
Plain-language R-value and cost ranges by insulation type, how attic, wall, and crawlspace insulation and air-sealing really work, energy-audit and utility-rebate help, how to vet an installer, and a free way to find licensed, insured insulation pros near you — in your language.
Thermline is a free matching service, not an insulation contractor. You compare quotes and choose who to hire.
What insulation costs per square foot, by type
Installed cost per square foot depends on the area, your R-value target, access, and whether old insulation is removed. These are estimates, not quotes.
| Insulation type | Installed / sq ft | What you're paying for |
|---|---|---|
| Blown-in (loose-fill) | $1 – $4 | Fast attic coverage, fills odd spaces, budget-friendly |
| Spray foam | $3 – $7 | Highest R-value per inch, seals air leaks, premium |
| Fiberglass batts | $1 – $3 | Lowest cost, best for open framing |
| Dense-pack (wall retrofit) | $2 – $5 | Insulates finished walls without a tear-out |
| Air-sealing add-on | $1 – $3 | Seals leaks so insulation can do its job |
Ranges are typical installed estimates per square foot, not quotes. Your real price depends on the area, R-value target, material, access, removal of old insulation, and your region. Utility rebates and tax credits can lower the net cost.
Know your insulation before you choose
A quick spec sheet on the materials that shape the R-value, the air-sealing, and most of the budget.
Insulation projects the installers we match handle
From an attic top-up to whole-home air-sealing — find the right kind of insulation project for your home.
Attic insulation
Attic insulation: blown-in, batt, and air-sealing the attic floor — the highest-payback insulation upgrade for most homes, and what it costs.
Learn more Insulation typesWall insulation
Insulating exterior walls, including dense-pack blown-in retrofit for finished walls — how it's done without a full tear-out, and typical costs.
Learn more Insulation typesCrawlspace & basement insulation
Insulating crawlspaces and basements — encapsulation, rim joists, and moisture control that keeps floors warmer and the home drier.
Learn more Insulation typesSpray foam insulation
Open- and closed-cell spray foam — high R-value per inch and built-in air-sealing, where it makes sense, and what it costs.
Learn more Insulation typesBlown-in & batt insulation
Loose-fill blown-in (fiberglass and cellulose) and fiberglass batts — the most common, budget-friendly insulation and how each is installed.
Learn more Insulation typesAir-sealing & weatherization
Sealing the leaks that waste heat — air-sealing the attic floor, rim joists, and gaps so your insulation can actually do its job.
Learn moreHow Thermline works
Four clear steps — and you stay in control the whole way.
Tell us about your project
Which area you want insulated, the material if you know it, your area, and how to reach you. Project and contact details only — never financial account numbers or sensitive records.
Get matched, free
We connect you with licensed, insured insulation installers near you, at no cost to you. You'll usually hear from more than one so you can compare.
Compare quotes in writing
Ask each installer for a written estimate with the price, material, coverage area, and the R-value the job will reach. The cheapest number on the phone is rarely the real bill — read the line items and compare like for like.
You choose & hire
You decide who to hire. Confirm the license and insurance, get everything in writing, ask about any rebates, and never pay a large deposit before a signed contract.
Insulation planning guides
Plain-language guides to R-value, costs, energy audits, utility rebates and tax credits, and choosing an installer you can trust.
How we are paid
Thermline is free for homeowners. The licensed installers we match you with pay a flat fee to receive your request. We never take a cut of your project price, and we never charge you to be matched.
Safer choices
Always hire licensed, insured insulation installers, verify the license and insurance yourself, get the price and scope in writing before any deposit, ask for the R-value the job will reach, and confirm any rebate or tax-credit details with the program directly.
Get matched with a licensed insulation installer — free
Tell us about your project and your area. We connect you, at no cost, with licensed, insured insulation installers near you. You compare and choose who to hire.