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R-49 is the common target for the roof or ceiling in cold and mixed climates. That is about 20 inches of blown fibreglass, 15 inches of blown cellulose, 16 inches of fibreglass batt or about 8 inches of closed-cell spray foam. Air seal the ceiling plane before adding any of it.
This rolls every part of the job into one number — attic, walls, floors, air sealing and removal — so you can compare it against a contractor's bid.
With these inputs:
| Result | Value |
|---|---|
| Attic | $2,520 |
| Walls | $3,640 |
| Floors / crawlspace | $1,380 |
| Air sealing | $420 |
| Removal & disposal | Not included |
| Project total | $7,960 |
| Blended cost per sq ft | $2.49 |
Each surface = area × installed (or material-only) rate · Air sealing and removal are added as line items · Project total = sum of every line
A typical 2,000 sq ft home runs $4,000 to $10,000 installed depending on how much of the envelope is touched and which materials are used. DIY on the attic alone is often under $1,500.
Always. Sealing the top plates, penetrations and attic hatch first is cheap and makes the insulation you add far more effective.
Air sealing first, then the attic, then the rim joist, then walls and floors. That order follows return per pound spent rather than visibility. Doing walls before the attic is common and is usually the more expensive path to a smaller improvement.
If you are hiring out, one visit is usually cheaper per square foot than several, because setup and mobilisation get shared. If you are doing it yourself, phasing by return lets you stop when the remaining work stops paying — and the attic alone often captures most of the available gain.
It can, and this is worth sequencing deliberately. A well-insulated house has a lower peak heat load, so a system sized for the old house will be oversized for the new one. If a boiler or furnace replacement is on the horizon, insulate first and size the equipment afterwards — otherwise you pay for capacity you have just made unnecessary.
Need the whole roof at once? The free roofing calculator works out roof area, squares, shingle bundles, underlayment, drip edge, ridge cap and installed cost from one set of measurements.