Insulation Cost Calculator

Blown cellulose to R-49 runs about $1,605 installed, or roughly $2,005 with the air sealing that should come with it. That lands inside HomeGuide's $900–$3,600 band for blown-in attic jobs. The same attic in closed-cell foam prices out near $8,987 — you buy it for the air barrier, not the R-value per dollar.

Per R-value, almost never — our model puts R-49 cellulose at about $1.60/sq ft versus $8.99/sq ft for closed cell. Foam earns its price in specific places: crawlspace and basement walls (a 600 sq ft crawlspace to R-15 runs about $2,392), rim joists, cathedral ceilings, and anywhere you need insulation, air barrier and vapor control in one thin layer.

Usually no — topping up sound, dry loose fill is standard practice and this calculator prices it at zero removal cost. Remove it when it is wet, moldy, soaked with rodent waste, flattened under debris, or when knob-and-tube wiring is buried in it. Vacuum-out runs $1–$3 per sq ft (Fixr quotes $1.50–$3); a 1,000 sq ft attic adds about $1,700 to this job.

DOE/ENERGY STAR zone guidance: attics R-49 to R-60 in cold climates (zones 4–8) and R-30 to R-49 in the hot South; walls R-13 to R-21; crawlspace walls R-15 to R-19; basement walls R-11 to R-21. In most of the country the existing attic is the weakest link — if insulation sits at or below the joists you are near R-19, and every added inch of cellulose is about R-3.5.

Accessible-space installs (attic floors, crawlspace, basement) usually need no permit — which is most of what this calculator prices. Expect one when walls are opened, when spray foam is applied to living-space surfaces (many jurisdictions require exposed foam to carry a thermal or ignition barrier, such as intumescent paint), or when buried knob-and-tube wiring must be decommissioned before the cavities are filled. Have the permit conversation before booking, not during: the answer can change the material — foam's ignition-barrier requirement is real money — and adds an inspection visit to the schedule. Permit habits vary a lot by city, so ask your contractor what your building department requires.

A 1,000 sq ft blown-in attic with air sealing is a half-day, two-person job — air sealing happens first, while the floor is still walkable, because the leaks hide under the new depth. Batts over the same area take 1–2 days because of fitting and cutting around wires and fixtures. Spray foam is 1–2 days of spraying plus re-entry time — households and pets stay out until the foam cures and the space airs out. Removal is the slow half of any job: vacuuming out a 1,000 sq ft attic adds most of a day before anything new goes in.

Blowing your own attic is the classic DIY: rental machines are cheap or often free with bag purchases. For the 1,000 sq ft R-49 job above, the bags and sealant run about $890 versus $2,005 installed — you'd keep roughly $1,115 for a weekend of hauling 40+ bags (HomeAdvisor pegs average-depth DIY attic savings at $575–$750). Batts are DIY-friendly too. Spray foam is not a homeowner job — missed spots, wrong thickness and off-ratio mixing are expensive to undo.

Drywall repair behind wall jobs, crawlspace encapsulation and vapor barriers, soffit-vent baffles (cheap and worth adding on a deep blown job — see the attic insulation calculator), duct sealing inside the space, and structural work around knob-and-tube. Rebates: federal insulation tax credits changed for 2026 — check your utility's efficiency rebates before you budget around one.