Insulation Cost Calculator

Adding insulation often pays back in 3–7 years through energy bill reduction.

Area sq ft

Per sq ft installed

Annual energy savings

Federal credit

State rebate

Payback (years)

4.8

Net cost

$1,900

20-year savings

$6,100

How the math works

Net = (area × $/sf) − federal credit − state rebate. Payback = net / annual savings.

1,500 × $1.80 = $2,700 − $600 − $200 = $1,900 / $400 = 4.8 years payback.

How to Use

Enter area sq ft.
Enter per sq ft installed.
Enter annual energy savings.
Enter federal credit.
Enter state rebate.
Read payback (years).

Frequently Asked Questions

Insulation cost benchmarks?

Blown-in cellulose attic: $1.20–2.50/sf. Blown-in fiberglass attic: $1.00–2.00/sf. Spray foam (closed-cell) attic: $3–6/sf. Spray foam wall (rim joist): $4–8/sf. Batt fiberglass walls (during reno): $1.50–3.50/sf. Mineral wool (Roxul): $2–4/sf, fire/sound resistant. Federal credit 25C: 30% up to $1,200 (insulation, air sealing, doors, windows combined). Energy savings: 10–30% on heat/cool bills depending on starting state.

How accurate is this estimate?

Material and labor estimates are accurate to ±15% with reasonable inputs but local market conditions vary. Major markets cost 30–60% more than rural. Labor rates regional (union vs non-union, prevailing wage). Material prices fluctuate with commodity cycles. Get 3 contractor bids for any work over $5k. This calculator is a sanity check, not a substitute for actual quotes.

DIY vs contractor?

DIY savings: 40–70% of contractor cost on labor. Realistic skill threshold: painting, basic plumbing, simple electrical, drywall, flooring. Pro required: structural, gas, complex electrical, HVAC, roofing (warranty + insurance), permits. Permitted work without license risks insurance and resale. Time: hobby DIYers 3–5x slower than pro. Tools and learning curve real.

Permit and code compliance?

Permits required for: structural changes, additions, electrical service changes, plumbing rough-in, HVAC replacement, roof replacement (varies), fence (varies). Cost: $50–2,000+ depending on scope. Skipping permit risks: stop work order, fines, forced removal, insurance denial, resale title issues. Always pull permit; cost is small relative to compliance friction.