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What to look for on an insulation quote
Insulation quotes should specify R-value, material type, square footage, and air sealing scope — not just a total price. The same dollar amount can deliver very different energy performance depending on these details.
Area covered: attic, walls, crawlspace, basement, or rim joists.
Attic: R-49 to R-60 in most climates. Walls: R-13 to R-23. Crawlspace: R-19 to R-30. Follow IRC 2021 or current climate zone code.
Fiberglass batts, fiberglass blown-in, cellulose blown-in, spray foam (open-cell or closed-cell), mineral wool, rigid foam.
Caulking, foam gun, rigid foam, or tape on penetrations, joist ends, top plates. Typically 20–40% of energy performance comes from air sealing, not just insulation.
Often needed on attic re-insulations with rodent contamination, moisture damage, or inadequate old material. $1–$3/sq ft.
Soffit intake + ridge exhaust. Required to prevent moisture and ice damming in cold climates.
Maintains airflow from soffit to ridge. Required under blown insulation in attics.
Required in cold climates (Zone 5+) on warm-side of wall/ceiling.
Sometimes required; usually not for like-for-like attic top-ups.
Material (manufacturer; R-value rated for life of product) + workmanship (5–lifetime).
Red flags in an insulation quote
Attic R-value below R-49 in most US climates is below code. A quote for "R-30 attic" in Zone 4+ is below-code work.
Insulation without air sealing loses 20–40% of its rated R-value. Comprehensive quotes include air sealing as a separate line.
Fiberglass blown-in is the cheapest material. If priced like cellulose or spray foam, you're overpaying. Expect $1–$2/sq ft for fiberglass blown-in vs $1.50–$3 for cellulose.
Open-cell spray foam absorbs water; closed-cell is the right choice for exterior walls and crawlspaces. A quote for open-cell in exterior should be scrutinized.
Baffles prevent blown insulation from blocking soffit airflow. Without them, attic ventilation fails and ice damming occurs.
Old fiberglass with rodent urine, mold, or asbestos (pre-1970s) needs proper containment and disposal. Skipping contamination handling is a health risk.
Spray foam is also an air barrier, but quality depends on application. Quote should include blower door test post-install to verify air sealing.
Common hidden costs and change orders
These items are often missing from the initial insulation quote and show up later as change orders or surprise fees. Ask about each before signing.
- Removal of old contaminated insulation ($1–$3/sq ft)
- Rodent exclusion / sealing before insulation ($200–$2,000)
- Knee wall insulation on story-and-a-half homes
- Attic stairs insulated hatch ($200–$500)
- Recessed light covers (airtight, IC-rated)
- Rigid foam on basement walls before fiberglass
- Structural attic flooring after insulation install