They lose R-value if compressed, so do not jam them into shallow cavities. Kraft-faced batts include a Class II vapor retarder, right for cold climates, wrong for hot-humid walls.<\/p>\n
Blown-in fiberglass<\/strong> ($1.00 to $2.50\/sq ft at R-30, $1.40 to $3.50\/sq ft at R-60) covers irregular cavities and attic floors quickly. R-value depends on installed density, which a trained installer achieves with the right machine pressure and nozzle.<\/p>\n Loose-fill cellulose settles about 10 to 20 percent over the first two years; blown-in fiberglass does not. Watch for bids that price “blown-in” without naming the material or the density.<\/p>\n Cellulose<\/strong> ($1.20 to $3.00\/sq ft at R-30, $1.80 to $4.20\/sq ft at R-60) is denser than fiberglass and fills small gaps that fill narrow channels.<\/p>\n Open-cell spray foam<\/strong> ($2.00 to $4.50\/sq ft at R-21, $3.00 to $6.00\/sq ft at R-30) is half-pound foam that fills cavities and seals air leakage in the same step.<\/p>\n It is vapor-permeable, so it does not belong on the exterior side of a cold-climate wall. Accessible surfaces need a thermal or ignition barrier (intumescent paint or a code-listed covering).<\/p>\n Closed-cell spray foam<\/strong> ($4.00 to $8.00\/sq ft at R-21, $5.50 to $11.00\/sq ft at R-30) is two-pound foam with the highest R-value per inch and acts as its own vapor retarder at 2 inches.<\/p>\n It is the right answer for rim joists, basement walls, masonry, and anywhere moisture is a concern. The cost is roughly double open-cell, but the air-sealing benefit and structural rigidity usually justify it.<\/p>\n Rigid foam board<\/strong> ($0.80 to $2.00\/sq ft at R-10, $1.60 to $3.50\/sq ft at R-20) is used as continuous insulation over exterior sheathing, under slabs, or against basement walls.<\/p>\n Polyiso (R-5.6 to R-6 per inch) is the highest-performing per dollar at moderate cost. XPS (R-5 per inch) is the most moisture-resistant. EPS (R-4 per inch) is the cheapest. Seams must be sealed with compatible tape to make the assembly continuous.<\/p>\n Mineral wool (rock wool)<\/strong> ($1.50 to $3.50\/sq ft at R-15, $2.50 to $5.50\/sq ft at R-30) is fire-resistant, water-repellent, and dimensionally stable.<\/p>\n Insulation cost varies by where in the house it goes. The labor share of the price differs a lot between a flat attic floor and a wall with windows and outlets.<\/p>\n Attic floor (open blow-in)<\/strong> is the cheapest place to add insulation because access is easy and the work is fast.<\/p>\n A 1,000 sq ft attic typically runs $1,500 to $3,500 for R-38 to R-60 with cellulose or blown fiberglass. The catch is air sealing: any gaps at top plates, chases, or recessed lights must be sealed first, which adds 4 to 8 hours of labor on a typical home.<\/p>\n Attic roof deck (spray foam against rafters)<\/strong> is the most expensive per square foot because the work is overhead and the assembly is open.<\/p>\n A 1,000 sq ft cathedral or unvented attic at R-30 with closed-cell spray foam runs $5,000 to $10,000. The benefit is bringing the roof deck inside the conditioned envelope, which eliminates ice dam risk and duct losses in HVAC-in-attic layouts.<\/p>\n Exterior walls (retrofit blown-in)<\/strong> requires access through the exterior siding or interior drywall.<\/p>\n Either approach costs $2 to $5 per sq ft of wall area, which translates to $4,000 to $12,000 for a typical 1,500 to 2,500 sq ft home with 8 to 10 ft ceilings. Dense-pack cellulose installed through small holes is usually the most cost-effective approach for existing walls.<\/p>\n Rim joists and basement walls<\/strong> are small areas with high impact.<\/p>\n A typical home has 100 to 200 linear feet of rim joist, plus 800 to 1,500 sq ft of basement wall. Closed-cell spray foam at the rim joist costs $400 to $900; XPS or polyiso against the basement wall costs $1,500 to $4,000. Together they typically run $2,000 to $5,000.<\/p>\n Crawl space walls<\/strong> in an encapsulation project run $4,000 to $10,000 for a 1,000 to 1,500 sq ft crawl space at R-21 with closed-cell spray foam.<\/p>\n Cathedral ceilings and sloped attic walls<\/strong> are the most variable. Closed-cell spray foam at R-30 to R-49 runs $7 to $15 per sq ft installed. Most projects of this kind are paired with a roof replacement, which lets the contractor work from the outside.<\/p>\n Two bids for the same project can differ by 50 percent and both be honest. The differences come down to scope, not gouging.<\/p>\n Air sealing.<\/strong> A bid that includes sealing every top plate, every wire and pipe penetration, and the attic hatch is worth more than a bid that does not. Expect $300 to $1,500 for air sealing on a typical home. Skipping it makes the insulation work less than the R-value suggests.<\/p>\n Removal of old insulation.<\/strong> Vacuuming out wet or moldy fiberglass or cellulose costs $1 to $3 per sq ft of floor area on top of the new insulation. If a contractor’s bid does not mention this and the project is a retrofit, ask whether the existing insulation is being removed.<\/p>\n Drywall and trim repair.<\/strong> Drilling access holes for dense-pack wall insulation and repainting costs $2 to $5 per sq ft of wall area. A bid that does not separate this line item is hiding it inside the per-square-foot price.<\/p>\n Vapor barrier and air barrier detailing.<\/strong> Continuous exterior rigid foam (R-5 to R-10 over the sheathing) adds $2 to $5 per sq ft of wall area. Class I vapor retarders on the interior side of cold-climate walls are sometimes priced separately as well.<\/p>\n Accessibility.<\/strong> Tight crawl spaces (under 24 inches of clearance), steep-slope attics, and complicated framing around HVAC runs add labor. A bid that does not include these in writing is a candidate for change orders.<\/p>\n Disposal fees.<\/strong> Vapor barriers, old insulation, and protective coverings add $200 to $800 to the typical job. Not glamorous, but they show up on the invoice.<\/p>\n Most insulation bids are honest; the bad ones share a few patterns. Watch for these.<\/p>\n Low per-square-foot price with no material specification.<\/strong> A bid at $0.85\/sq ft that does not say what is being installed or at what R-value is not a real bid. Get three bids in writing that each name the material, the R-value, the air-sealing scope, and the access method.<\/p>\n Spray foam without a thermal\/ignition barrier line.<\/strong> Spray foam in accessible areas (most basements and rim joists) needs a listed thermal or ignition barrier. A bid without one may need an extra $1,500 to $4,000 to bring the assembly up to code.<\/p>\n No moisture assessment on a retrofit.<\/strong> A bid to install insulation without first inspecting for bulk water, vapor drive, or previous mold is risky. The contractor is pricing insulation, not the whole assembly, and the moisture side may fail later.<\/p>\n Skip-the-inspection spray foam estimates.<\/strong> Reputable foam contractors pull a permit (where required), inspect the cavity, and confirm the substrate is dry before spraying. A bid that skips all of these is a sign the contractor is planning to spray over whatever is there.<\/p>\n Outside a DIY scope: closed-cell spray foam over an entire roof deck, dense-pack cellulose retrofits on multi-story walls with difficult access, and any job that touches knob-and-tube wiring. These projects benefit from a structural or insulation specialty contractor and usually pay for themselves in energy savings within 7 to 10 years.<\/p>\n To see how the work should be sequenced for a moisture-prone assembly, the insulation and mold guide<\/a> walks through the order of operations that prevents problems. To see the crawl-space-specific project in detail, the how-to-insulate-crawl-space<\/a> guide covers air sealing, vapor barrier, and the rim-joist detail that most cost guides gloss over.<\/p>\n","protected":false},"excerpt":{"rendered":" Insulation installation costs vary by a factor of three or four across a normal home, and most of that variance comes down to a handful of decisions. The four that matter: the material, the R-value you are trying to hit, the surface area being covered, and whether the work is new construction or a retrofit. […]<\/p>\n","protected":false},"author":2,"featured_media":1017,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[74],"tags":[93],"class_list":["post-1018","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-insulation","tag-insulation"],"_links":{"self":[{"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/posts\/1018","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/comments?post=1018"}],"version-history":[{"count":1,"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/posts\/1018\/revisions"}],"predecessor-version":[{"id":1019,"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/posts\/1018\/revisions\/1019"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/media\/1017"}],"wp:attachment":[{"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/media?parent=1018"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/categories?post=1018"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.skala8.com\/blog\/wp-json\/wp\/v2\/tags?post=1018"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Cost by Location: Where the Money Goes<\/h2>\n
![\"insulation](\"\/blog\/wp-content\/uploads\/insulation-installation-cost-guide.jpg\")
What Drives the Quote Beyond the Material<\/h2>\n
Limits, Edge Cases, and How to Spot a Bad Quote<\/h2>\n