Attic insulation by state
The insulation and process are the same everywhere - pick your state for a page matched to where you are.
How blown-in insulation is actually installed
Four steps, done in order. The Department of Energy is explicit that skipping the air-sealing step is the most common way a new insulation job still leaves an attic underperforming.
- 1
Air seal first
The EPA recommends sealing attic-floor penetrations before insulating, because loose-fill does not stop air moving through gaps around wiring, pipes and fixtures.
- 2
Add baffles and depth markers
Rafter baffles keep blown material off the eaves where it could get wet, and depth rulers mark the target R-value before the blower starts.
- 3
Blow to depth
A pneumatic machine feeds loose fiberglass or cellulose over the attic floor, covering the tops of the joists so heat cannot bypass the insulation.
- 4
Verify and clean up
The settled depth gets checked against the target R-value for your climate zone, then tools and debris are cleared.
What this site will and will not do
We explain the R-value target and the real cost drivers first, and we do not sell you the installation - which is why we can say plainly when topping up beats a full replacement.
R-value before a quote
ENERGY STAR recommends R-30 to R-60 depending on your climate zone. Knowing your target before you call means you can hold every bid to the same number.
Air sealing first, always
The Department of Energy is explicit that insulation slows heat flow but does not stop air leaks - sealing gaps first is what makes the insulation you pay for actually perform.
We are not the installer
We do not install anything ourselves, so we have nothing to gain from steering you toward the bigger job. Licensed local companies do the work and quote it themselves.
Nothing we cannot source
Every figure on this site traces to a named, dated source - HomeAdvisor, the DOE, ENERGY STAR, the EPA or the FTC. Where we have not sourced a number, we say so instead of guessing.