How Much Does Insulation Cost? (2026 Renovation Guide)
A complete breakdown of insulation costs by type, location, and R-value — plus how to decide between DIY and professional installation.
Last updated: May 2026
| Item / Category | Low End | Average | High End |
|---|---|---|---|
| Fiberglass Batts (per sq ft) | $0.50 | $0.85 | $1.50 |
| Blown-In Cellulose (per sq ft) | $1.00 | $1.40 | $2.00 |
| Blown-In Fiberglass (per sq ft) | $1.00 | $1.50 | $2.20 |
| Open-Cell Spray Foam (per sq ft) | $1.00 | $1.50 | $2.50 |
| Closed-Cell Spray Foam (per sq ft) | $2.00 | $3.00 | $4.50 |
| Rigid Foam Board (per sq ft) | $0.75 | $1.25 | $2.50 |
| Attic (1,000 sq ft Total) | $1,500 | $2,500 | $6,000 |
| Exterior Walls (Total) | $2,000 | $4,000 | $8,000 |
| Crawl Space (Total) | $1,000 | $2,500 | $5,000 |
| Professional Labor (per sq ft) | $0.50 | $1.00 | $2.50 |
Insulation Renovation Cost
A full insulation renovation — removing old, degraded insulation and installing new material — costs $1.50–$4.50 per sq ft for the combined removal and replacement. Removal alone runs $1–$3 per sq ft (more if the old material is contaminated by rodents, mold, or moisture), and the new insulation adds $0.50–$2.50 per sq ft depending on the type you choose. For a whole-home insulation renovation covering the attic and exterior walls, most homeowners spend $3,000–$10,000. A renovation makes sense when the existing insulation is wet, moldy, pest-damaged, or contains vermiculite (which may hold asbestos and requires professional abatement). If your current insulation is dry, clean, and simply too thin, a top-up is far cheaper — blowing new cellulose or fiberglass over what's already there costs $1–$2 per sq ft with no removal fees. Insulation renovations are often bundled into larger remodels: if walls are already open for an addition or gut renovation, insulating them costs 30–50% less than retrofitting closed walls. Use our attic insulation calculator to estimate how much material your renovation will need.
Insulation Cost Per Square Foot
Installed insulation prices per square foot vary mainly by material type. Blown-in products are the cheapest to have installed, batts sit in the middle, and spray foam commands the highest rates because of equipment and skill requirements:
| Insulation Type | Installed Cost (per sq ft) |
|---|---|
| Blown-In Fiberglass | $0.50–$1.10 |
| Blown-In Cellulose | $0.60–$1.20 |
| Fiberglass Batts | $0.80–$1.50 |
| Open-Cell Spray Foam | $1.50–$2.50 |
| Closed-Cell Spray Foam | $2.50–$4.50 |
These rates assume standard depths in accessible areas. Reaching higher R-values, working in tight spaces, or removing old material first pushes costs toward the top of each range. Not sure whether blown-in fiberglass or cellulose is right for your project? See our fiberglass vs cellulose comparison for a side-by-side breakdown, or run your numbers through the insulation calculator.
Cost of Adding Insulation to Existing Walls
Adding insulation to existing, closed walls costs more per square foot than insulating open walls because the installer has to work blind through small openings. The most common method is dense-pack blown-in insulation: the contractor drills a 2–3 inch hole in each stud bay (from inside or outside), fills the cavity with cellulose or fiberglass, then plugs and patches the holes. Expect $1.50–$3.50 per sq ft including patching. Injection foam — a slow-rise foam pumped into the cavity the same way — runs $2.00–$4.00 per sq ft and adds air sealing that loose-fill can't match. By comparison, batts in open walls cost only $0.80–$1.50 per sq ft, which is why insulating during a remodel (while the drywall is already off) is so much cheaper. The premium for existing walls covers the drilling, the specialized dense-pack equipment, the drywall or siding repair afterward, and the extra labor of verifying every bay is completely filled. For a typical 1,500 sq ft of exterior wall area, budget $2,500–$5,500 for dense-pack or $3,000–$6,000 for injection foam.
Average Costs by Project Size
Insulation costs scale with the area covered and the type chosen. Insulating a 1,000 sq ft attic with blown-in cellulose to R-38 (the code minimum in most climates) costs $1,500–$3,000 installed. The same attic with open-cell spray foam runs $2,500–$4,500, and closed-cell spray foam costs $3,500–$6,000. Insulating exterior walls in an existing home is more expensive per square foot because it often requires drilling holes and dense-packing insulation or removing siding — expect $2,000–$8,000 for a full home. Crawl space insulation (floor joists and perimeter walls) typically runs $1,000–$5,000 depending on access, size, and whether a vapor barrier is included.
Factors That Affect Cost
Several factors influence your total insulation cost:
- Insulation type: Fiberglass batts are the cheapest option. Blown-in cellulose and fiberglass offer better coverage at moderate cost. Spray foam is the most expensive but provides superior air sealing and R-value per inch.
- R-value requirements: Higher R-values require more material. Attics in cold climates need R-49 to R-60 (13–17 inches of blown-in), while mild climates may only require R-30 to R-38.
- Accessibility: Easy-access open attics are the cheapest to insulate. Enclosed walls, cathedral ceilings, and tight crawl spaces cost more because installation is slower and may require specialized equipment.
- Existing insulation removal: If old insulation needs to be removed (due to contamination, mold, or vermiculite/asbestos), expect to add $1–$3 per sq ft for removal and disposal.
- Air sealing: Properly air-sealing gaps, cracks, and penetrations before insulating adds $500–$1,500 but significantly improves performance. Many contractors include this in their insulation package.
- Geographic location: Energy codes, climate zones, and local labor rates all affect pricing. Cold-climate homes need more insulation, and labor rates vary by region.
DIY vs Hiring a Pro
Fiberglass batts are the most DIY-friendly insulation type. You can insulate an open attic or exposed wall cavities with batts for roughly $0.25–$0.75 per sq ft in materials, saving 40–60% over professional installation. Many home improvement stores offer free blown-in machine rentals when you buy a minimum number of bags, making blown-in attic insulation another good DIY project ($0.50–$1.00 per sq ft in materials). Spray foam, however, should almost always be installed by a professional — it requires specialized equipment, proper mixing ratios, protective gear, and experience to apply correctly. Poorly applied spray foam can off-gas, shrink, or fail to adhere properly.
How to Save Money
- Start with the attic: Attic insulation offers the best return on investment because heat rises. Adding insulation to an under-insulated attic is the single most cost-effective energy upgrade.
- DIY fiberglass batts or blown-in: Installing batts in an open attic or using a free rental blower for blown-in can cut costs by 40–60% compared to hiring a contractor.
- Air seal first: Sealing gaps around pipes, wiring, recessed lights, and ductwork before insulating boosts performance significantly. A tube of fire-rated caulk and a can of expanding foam cost under $20.
- Check for utility rebates: Many utility companies offer $200–$1,000 in rebates for adding insulation, especially when paired with an energy audit. Some states also offer tax credits.
- Add to existing insulation: If your current insulation is in good condition, you can add more on top rather than removing and replacing it. Blown-in over old batts works well in attics.
- Get multiple quotes: Insulation contractor pricing varies widely. Get at least three quotes and ask about package deals that include air sealing.
When to Splurge vs Save
Splurge on spray foam for rim joists and band joists. These areas are notorious air leaks, and closed-cell spray foam provides both insulation and a complete air and moisture barrier in one application. The cost for this small area is typically $300–$800 and the energy savings are disproportionately large. Save on attic insulation by using blown-in cellulose or fiberglass instead of spray foam — in an open attic, blown-in delivers excellent R-value at one-third the cost of spray foam. Splurge on proper air sealing before any insulation work — air leaks can reduce insulation effectiveness by 25–40%. Save by doing attic insulation yourself — blown-in attic insulation is one of the most accessible DIY energy projects, especially with free blower machine rentals from home improvement stores.
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Calculate How Much Insulation You Need →Frequently Asked Questions
Fiberglass batts are the cheapest insulation type at $0.50–$1.50 per sq ft installed (or $0.25–$0.75 per sq ft for materials only if you DIY). Blown-in cellulose is the next most affordable at $1–$2 per sq ft installed. Both provide good thermal performance for most applications. Fiberglass batts are best for open wall cavities and accessible attics, while blown-in works better for covering irregularly shaped spaces and adding to existing insulation.
For most homeowners, blown-in cellulose or blown-in fiberglass is the best attic insulation. It fills gaps and covers irregularities better than batts, installs quickly, and costs $1–$2 per sq ft. It can be added over existing insulation to reach current code requirements (R-38 to R-60 depending on climate zone). Spray foam is the premium option — it provides superior air sealing and the highest R-value per inch — but costs 2–3 times more and is overkill for many open attic applications.
Open-cell spray foam costs $1–$2.50 per sq ft installed and provides about R-3.5 per inch. Closed-cell spray foam costs $2–$4.50 per sq ft installed and provides about R-6.5 per inch. For a 1,000 sq ft attic, open-cell spray foam runs $2,500–$4,500 and closed-cell costs $3,500–$6,000. Spray foam is more expensive than other types but provides superior air sealing, acts as a moisture barrier (closed-cell), and offers the highest R-value per inch of any insulation type.
Yes, fiberglass batts and blown-in insulation are good DIY projects for accessible areas like open attics and exposed wall cavities. Fiberglass batts simply cut to size and press-fit between joists or studs. For blown-in, many home improvement stores loan blower machines free when you buy a minimum number of bags (usually 10–20). Wear long sleeves, gloves, goggles, and an N95 mask. Spray foam should be left to professionals due to equipment requirements and safety concerns. Always check local building codes for R-value requirements in your climate zone.
Adding insulation to an under-insulated home typically saves 10–30% on heating and cooling costs. The exact savings depend on your current insulation level, climate, energy prices, and home size. Attic insulation upgrades offer the fastest payback — typically 2–4 years for blown-in cellulose. Wall insulation payback is longer (5–10 years) due to higher installation costs. The Department of Energy estimates that proper insulation and air sealing can save the average homeowner $200–$600 per year on energy bills.
A full insulation renovation — removing old insulation and installing new — costs $1.50–$4.50 per sq ft for removal plus replacement. A whole-home renovation covering the attic and exterior walls typically runs $3,000–$10,000. Renovation is worth it when old insulation is wet, moldy, or pest-damaged; if it's simply too thin, topping up with blown-in over the existing layer costs far less at $1–$2 per sq ft.
Installed insulation costs $0.50–$4.50 per sq ft depending on type. Blown-in fiberglass runs $0.50–$1.10, blown-in cellulose $0.60–$1.20, and fiberglass batts $0.80–$1.50 per sq ft. Spray foam is the most expensive: open-cell costs $1.50–$2.50 and closed-cell $2.50–$4.50 per sq ft installed. Higher R-value targets and hard-to-access areas push prices toward the top of each range.
Adding insulation to existing closed walls costs $1.50–$3.50 per sq ft for dense-pack blown-in installed through drilled holes, including patching, or $2.00–$4.00 per sq ft for injection foam. That's roughly double the cost of insulating open walls because of the drilling, specialized equipment, and drywall or siding repair involved. For a typical home with 1,500 sq ft of exterior wall area, budget $2,500–$6,000.