Insulation Cost Calculator

Most 1,200 sq ft attics run $1,700 to $3,200 installed with blown fiberglass or cellulose at R-49. DIY with rented equipment usually lands between $900 and $1,500.

Typically yes — an under-insulated attic upgrade cuts 10 to 20% off heating and cooling bills, so most jobs pay back in 3 to 7 years. Utility and state rebates, where offered, shorten that further (the federal 25C tax credit ended on December 31, 2025).

For blown-in attic work, substantially — the material is a minority of a contracted price and blower rental is often waived with a bag purchase. For spray foam it usually is not, once you price kits against contractor board-foot rates. For walls needing dense-pack it is rarely practical without the equipment. The calculator splits material from labour so the comparison is visible.

Surface area and R-value target, in that order, with access as the wildcard. A tall building has disproportionately more wall than floor; a high R target means more depth and more material; and a crawlspace you cannot stand up in costs more per square foot than an open attic for identical work. Quote on surface areas, not on the house's floor area.

Frequently, through federal programmes, state schemes and utility companies, and they are often stackable. They also change year to year and by location, which is why this site does not quote figures it cannot keep current — check your utility's current offer and your state energy office before assuming a price, because the rebate can meaningfully change which option is cheapest.