Insulation gets confusing once you start comparing materials, R-values, and the very different prices contractors throw around in Seattle.
Some homes only need a quick attic top-up. Others need removal, air sealing, or moisture work before new insulation can even go in.
To make the numbers easier to sort through, we’ll break down realistic costs, what drives them, and how to estimate your own project.
Key Notes
Seattle insulation costs range from $1.10–$4.50 per sq ft, depending on material.
Old insulation removal adds $1–$2 per sq ft to total pricing.
Air sealing, moisture prep, and labor conditions can increase bids by 30–100%.
Seattle Insulation Installation Cost Per Square Foot
Most insulation installation in Seattle falls between $1.10 and $4.50 per square foot, depending on the material and job conditions.
The type of insulation is the biggest driver of price – some require simple placement, others need specialized equipment or climate‑specific prep.
Cost by Insulation Type (Installed)
Blown‑in (cellulose or fiberglass): $1.30–$3.50/sq ft
Batt & roll fiberglass: $1.13–$3.50/sq ft
Spray foam: $1.80–$4.50/sq ft
Loose‑fill: $1.60–$4.20/sq ft
Reflective insulation: $0.50–$2.00/sq ft (less common in Seattle’s climate)
The low end reflects simple installs in accessible areas. The high end usually includes tricky access, higher R‑values, or Seattle’s climate‑driven moisture work.
What Impacts Price Per Square Foot?
R‑value (higher R means more material or density)
Moisture resistance requirements
Installation method (spray foam takes more labor + equipment)
Whether the area is open or requires removal
Attic/crawlspace access challenges
Total Project Cost: Typical Seattle Pricing
Square‑foot pricing is a starting point. Total project cost depends on the size of the space, how easy it is to work in, and whether prep or removal is needed.
Here’s what homeowners typically pay for complete insulation installs in Seattle:
Area | Typical Cost Range | Notes |
Attic | $3,000–$5,000 | Larger or complex up to ~$6,750+ |
Walls (remodel) | $2,000–$5,000 | Walls must already be open |
Crawlspace | $2,600–$7,000+ | Average around $3,550 for 1,000 sq ft |
Basement (unfinished) | $1,800–$3,000 | Insulation only |
Attic Insulation Cost
Most attic insulation projects in the Seattle area fall between $3,000 and $5,000.
For larger attics or homes where old insulation needs to be removed and air sealed first, totals often reach $6,000+.
Example: 1,500 sq ft attic → $3,750–$6,750 depending on material and prep.
Wall Insulation Cost (During Remodel)
When walls are already open – no demo just for insulation – Seattle projects tend to cost $2,000–$5,000, depending on how many rooms you’re tackling.
National data for 2025 puts most wall insulation jobs between $1,400 and $6,300, so Seattle’s ranges fall right in the middle.
Crawlspace Insulation Cost
Crawlspaces are their own world. Tight access, moisture, and Seattle’s older homes can all change the cost quickly. Expect $2,600–$7,000+, with many homeowners landing around $3,550 for a 1,000 sq ft space.
Basement Insulation Cost
Basement insulation (unfinished areas) normally costs $1,800–$3,000 (not including any waterproofing or remodel work).
Factors That Affect Insulation Installation Cost
Every home has its own quirks. These are the biggest cost drivers contractors consider when quoting insulation in Seattle:
Material Choice
Different insulation types come with different labor, equipment, and prep needs.
Spray foam offers excellent performance but sits at the top of the price range. Blown‑in cellulose is popular for attics because it balances cost and performance well.
Removal of Old Insulation
If old insulation needs to be vacuumed and bagged, expect $1.00–$2.00 per square foot added to the project.
Removal is especially common in Seattle homes with:
Moisture damage
Rodent activity
Older insulation that has lost effectiveness
Asbestos‑era materials (which require specialty abatement teams)
Access Difficulty
The harder it is to reach the area, the longer the job takes.
Common Seattle access issues:
Tight crawlspaces
Steep attic pitches
Small attic hatches
Blocked wall cavities
Expect a 20–50% labor premium or an added $0.50–$1.50 per sq ft for hard‑to‑reach spaces.
Air Sealing & Moisture Prep
Seattle’s wet climate makes air sealing and moisture work more important than in many other cities.
Typical add‑on costs:
Air sealing: $300–$800 per project
Moisture/cleaning prep: $200–$600
Skipping these can lead to trapped moisture, mold issues, or insulation that underperforms.
R‑Value & Climate Requirements
Seattle sits in a climate zone that demands higher R‑values than most coastal cities.
Seattle attic recommendation: R‑49 to R‑60
Higher R‑values can mean more material, dense‑pack approaches, or additional layers – all of which influence cost.
How to Estimate Your Insulation Installation Cost?
If you want a ballpark number before getting quotes, here’s a simple way to do it:
Step 1: Measure The Space
Use the attic or room’s footprint.
For walls, multiply wall length × height and subtract windows/doors.
Step 2: Pick Your Material
Attics: blown‑in
Crawlspaces: batts
Efficiency upgrades: spray foam
Step 3: Add Prep or Removal Costs
Removal: $1–$2/sq ft
Air sealing: $300–$800
Moisture prep: $200–$600
Step 4: Add Access Adjustments
Tight crawlspaces or steep attics – add 20–50% labor
Step 5: Calculate Your Range
Total Cost ≈ (Sq ft × Material Rate) + Removal + Prep + Air Sealing + Access Adjustments
If you’re within Seattle city limits or working in an older home, lean toward the higher end of your range.
Benefits & ROI of Proper Insulation in Seattle
Done right, insulation is a long‑term upgrade that pays you back.
Lower Utility Bills
Seattle homeowners usually see 15–20% heating energy savings after upgrading insulation.
Better R‑values slow down heat loss during damp, chilly winters. That means your heating system doesn’t have to fight drafts all season.
Comfort That You Can Feel
Fewer cold spots
Quieter rooms
More consistent temperatures across the home
Less condensation on walls or windows
Seattle homes with proper insulation simply feel better to live in.
Moisture Control
In this climate, air sealing + insulation prevents moisture ingress – one of the biggest triggers for mold and mildew.
Higher Home Value
Energy‑efficient upgrades show up well in inspections and can make a listing more competitive.
Rebates & Incentives
Seattle City Light and other local programs periodically offer help for insulation and energy‑efficiency improvements. Savings vary by year, but it’s always worth checking.
Frequently Asked Questions
How long does insulation last in Seattle’s climate?
Most insulation lasts 20–30 years, but moisture, pests, and settling can shorten that lifespan. Seattle’s damp winters make periodic checks worthwhile, especially in attics and crawlspaces where moisture tends to show first.
Can new insulation be added on top of old material?
Sometimes – but only if the existing insulation is dry, clean, and intact. If it’s compressed, wet, or moldy, it needs to be removed first to avoid trapping moisture or reducing performance.
Does insulation help with noise between floors or shared walls?
Yes. Fiberglass batts and dense-pack cellulose both help reduce sound transfer and are common choices for multi-family homes or remodels where quieter rooms matter.
Will insulation help with drafts or cold spots?
Insulation helps, but it’s air sealing that stops the actual drafts. In Seattle homes, the best results come from doing both — sealing gaps first, then insulating to stabilize temperature throughout the house.
Want An Insulation Quote That’s Tailored To You?
Lower bills, quieter rooms & a cleaner install from start to finish.
Conclusion
Upgrading insulation is one of the simplest ways to cut heating costs in a Seattle home, but the total depends on a few numbers.
Most installs land between $1.10 and $4.50 per sq ft, with full attic projects typically running $3,000 to $5,000 and crawlspaces ranging $2,600 to $7,000+ depending on access and moisture prep.
Old insulation removal can add $1–$2 per sq ft, and air sealing often runs $300–$800, which is why two homes with the same square footage can end up with very different insulation installation cost totals.
When you know what drives pricing – material type, R-value, removal, and Seattle’s damp conditions – you can plan the project without guesswork.
If you want clear pricing and a clean install that supports better comfort year-round, request a free quote. We’ll look at your space, break down the numbers, and outline the best options for your home.
