A whole-house insulation quote is really four separate jobs with four different returns. They are almost never worth doing at the same time, and the order matters more than the total.
Here is what each one costs on a typical 1,800 sq ft two-storey US house, and the order that gets the most out of a limited budget.
What each assembly costs
| Assembly | Typical area | Installed | Notes |
|---|---|---|---|
| Attic floor, top up to R-49 | ~900 sq ft | $1,600 – 3,200 | Loose fill over sealed ceiling |
| Attic air sealing | — | $400 – 1,200 | Do this first, always |
| Rim joist, closed-cell foam | ~150 lin ft | $600 – 1,500 | Small area, large effect |
| Crawlspace or floor over unheated space | ~900 sq ft | $1,800 – 4,000 | Depends on encapsulation |
| Existing walls, dense-pack from outside | ~1,600 sq ft | $3,000 – 7,000 | Drill-and-fill, siding patched |
| Basement walls, rigid or closed-cell | ~800 sq ft | $2,500 – 6,000 | Includes vapour strategy |
Typical US contractor pricing at the time of writing, not quotes. A whole-house package touching everything runs $9,000 – 20,000, and almost nobody should buy it as one job.
The order that pays
1. Attic air sealing — $400 to $1,200. Nothing else on the list returns as much per dollar. Warm air leaves through gaps in the ceiling plane by convection, and insulation does not stop air. Sealing the top plates, chimney chase, dropped soffits, wire penetrations and the hatch is the highest-value work in the house. It is also the work most often skipped, because once insulation is blown over the top nobody can tell whether it was done. See the attic air sealing checklist.
2. Attic insulation — $1,600 to $3,200. The attic is the biggest single heat-loss surface, the cheapest per R to fix, and the only assembly where depth is free. Get it to your zone's target and stop; see recommended R-value by climate zone.
3. Rim joists — $600 to $1,500. Small area, disproportionate effect, and the assembly most likely to be doing nothing at all in an older house. Fast, and it fixes a condensation point as well as a heat loss. See how to insulate a rim joist.
4. Floors and crawlspace — $1,800 to $4,000. Worth doing for comfort — cold floors are the complaint people actually notice — more than for the energy bill.
5. Walls — $3,000 to $7,000. Last, and this surprises people. Walls are a large area, but they are usually already partially insulated, they are expensive to reach, and the marginal R gained is small relative to the cost. An uninsulated wall cavity is a different matter and moves up the list.
The pattern is simple: the first third of the budget buys most of the result. Spending $2,500 on sealing and attic gets you most of what $16,000 on everything gets you.
Where the whole-house quote goes wrong
No air-sealing line. If the quote insulates without sealing, it is selling the less effective half of the job. Ask for it as a separate line with a separate price.
One number for everything. Four assemblies with four different returns bundled into one figure cannot be evaluated. Ask for it broken out; then you can buy the top of the list this year and the rest later, or never.
Walls sold first. Walls are the biggest line and the slowest return. A quote that leads with walls and treats the attic as an add-on has the priority backwards.
R-value with no air barrier strategy. In a wall or an unvented roof, how the assembly handles moisture matters as much as its R. See vapor barrier: which side.
What it is worth
Energy savings from a full package on a leaky older house typically run $300–800 a year — real, but the whole-package payback is long. The sealing-plus-attic subset, at maybe $2,500, captures a large share of that saving and pays back in a handful of years. The rest is bought for comfort, and that is a legitimate reason as long as it is the reason. See insulation payback period.
The short version
Budget $2,000 – 4,400 for sealing plus attic and do that first. Add rim joists for another $600–1,500. Treat floors and walls as comfort purchases to be made later, separately, and only after the cheap work above is finished.