How Much Does Attic Insulation Cost?

What does each level of attic insulation cost?

We price an attic of up to 1,500 sq ft at three levels. Each starting price includes a standard material allowance, and upgrades are priced from your selections. The starting prices reflect typical completed projects in the Greater Seattle area. They are not a quote: every attic is priced in writing after a site visit.

We do not publish a per square foot price, because two attics of the same size can need very different work. The removal, air sealing and access lines are what separate them.

Source: our Insulation Installation Services page, prices as published October 2026.

What changes the price of attic insulation?

Three things set most of the price: the area insulated, the condition of the old insulation and the method. Several smaller items sit inside those three:

• Area and depth. The ceiling area times the depth needed to reach code sets the amount of material. An attic with a few inches of dry fill needs less new material than a bare one.
• The old insulation. Dry insulation can often stay under a top up. Wet, matted or rodent damaged insulation has to come out first. That moves the job from Basic to Mid-Range.
• Air sealing. Gaps around light fixtures, pipes, chimneys and the hatch let warm air into the attic. Sealing them comes before any insulation goes down.
• Eaves and the hatch. Baffles keep insulation clear of the soffit vents, and the hatch gets insulated and weatherstripped. Both are small items on the estimate.
• Access. A tall attic with a walk up stair is quick to work in. A low attic reached through a closet hatch, with wiring and ducts in the way, takes longer.

How much insulation does an attic need in Washington?

The target is R-60. The Washington State Energy Code, Table R402.1.3 (WAC 51-11R-40213, effective March 15, 2024) lists a ceiling R-value of 60 for Climate Zone 5 and Marine 4, which covers the Greater Seattle area. Its footnote e allows R-38 for single rafter or joist vaulted ceilings when the full depth extends over the top plate of the exterior wall.

Section R402.2.1 of the same code (WAC 51-11R-40220, effective March 15, 2024) adds: "installing R-49 over 100 percent of the ceiling area requiring insulation shall satisfy the requirement for R-60" where the full height of uncompressed R-49 extends over the wall top plate at the eaves. The same section requires a baffle next to soffit and eave vents for air permeable insulation in vented attics (R402.2.3), and an attic hatch insulated to the ceiling R-value (R402.2.4).

When we top up an existing attic, we work to these numbers. Our Basic level is priced as "blown in insulation to code depth".

Is blown in insulation cheaper than spray foam?

Yes. A blown in top up is our Basic level at $5,000+, and spray foam is our Luxury level at $15,000+, each for an attic up to 1,500 sq ft. Mid-Range removes the old insulation and installs new insulation to code. Blown in insulation covers an open attic floor fast and fills around joists and wiring. The energy code limits loose fill to ceilings with a slope of no more than 3 in 12 and at least 30 inches of clear height at the ridge (WAC 51-11R-40220, Section R402.2.1.1, effective March 15, 2024).

Spray foam seals air and insulates in one step. It suits tight rafter bays, and it costs more. Batts fit open, regular framing, such as rafter bays in an attic being finished as a room. Which method fits depends on the shape of your attic and whether it stays storage or becomes living space.

What is not included in the starting price?

Four items sit outside our starting prices, and we price them in writing if your attic needs them:

• Asbestos or vermiculite removal.
• Rodent cleanup beyond normal debris.
• Electrical repairs found during the work.
• Drywall work for wall insulation.

Old vermiculite or heavy rodent damage shows up only when we go into the attic. That is why the estimate comes after the site visit.

What does insulation cost when the attic becomes a room?

When an attic becomes living space, the insulation moves from the attic floor up to the roof slope and the knee walls. It then becomes one line inside a larger remodel. Our Attic Bonus Room Remodel in 2021 cost about $35,000 in total. In it the knotty pine paneling came down, the attic was stripped to the rafters, and insulation went into the roof between the rafters and into the walls before drywall, recessed lights and carpet went in.

A room under the slope also changes the code target: a single rafter vaulted ceiling can use R-38 when the full depth reaches over the wall top plate. A finished attic can hold a full bathroom too, like the walk-in shower in this Seattle attic bathroom remodel, a project of about $30,000 in 2021.

Do you need a permit to insulate an attic in Seattle?

Usually not. The 2021 Seattle Residential Code, Section R105.2 lists "insulating existing buildings" as minor work that needs no building permit, "provided no changes are made to the building envelope". Section R105.1 adds that "All work shall comply with this code, even where no permit is required".

Changing the roof framing or the building envelope takes the job outside that exemption. We check the permit rules in your city before we price the work. For the wider picture, read Do you need a permit to remodel in Seattle?

How long does attic insulation take?

An attic takes 1 to 4 days on site, after any permits the job needs. A crawl space takes 1 to 5 days, and a whole house up to 2 weeks.

Insulation often fits into a longer list of work. One Auburn household had a first bathroom, insulation, drainage, a fence and a new roof done with us around the same time.

How do we price your attic?

We go up into the attic, measure the area and the depth of what is there, and look for wet spots, gaps and rodent signs. We check the eaves, the vents and the hatch, and take photos. You then get a written estimate with removal, air sealing, baffles, material and labor each on its own line.

The service, the three levels and the crawl space and whole house prices are on Insulation Installation Services Across the Greater Seattle Area. We work from offices in Bellevue, Seattle, Monroe, Tacoma and Renton; see Home Remodeling Contractors in Seattle, WA and Home Remodeling Contractors in Bellevue, WA for the work we do in those cities.