Closed cell or open cell, matched to the surface
Spray Foam Insulation in Duluth, MN
Foam that seals air and insulates in one pass, used where it earns its cost.
- Free on-site estimates
- Written quote showing material, thickness and R-value for each area
- Attics, rim joists and basements checked for moisture before anything is covered
What Spray Foam Does That Other Insulation Cannot
Spray foam insulation is sprayed as a liquid that expands and hardens in place, so it fills the gaps that batts and loose fill leave open. In a Duluth house that matters most where cold air gets in: the rim joist sitting on top of the foundation, the joint between the basement wall and the sill, rafters in a finished half-story, and any cavity with wiring and pipes running through it. Foam seals those and insulates them at the same time.
Closed-cell foam
Closed-cell foam is dense and rigid. HomeGuide rates it about R-5 to R-7 per inch, and at normal thickness it slows water vapor and does not soak up water. That makes it the usual choice for rim joists, basement and crawl space walls, sloped ceilings with shallow rafters, and steel garages and shops where condensation forms on the metal. It costs more per square foot, roughly $3.00 to $5.00 installed in HomeGuide's guide.
Open-cell foam
Open-cell foam is soft and spongy, about R-3.5 to R-3.7 per inch, and roughly $1.50 to $3.50 per square foot installed. It seals air well and is useful for interior walls and some roof assemblies. It lets water vapor pass, so in a cold climate it is not the choice for a wall against a cold foundation, and in a roof assembly it needs vapor control. We will not put open-cell where it invites condensation.
When foam is not the best value
On a big, open attic floor, sealing the leaks and then blowing in cellulose or fiberglass to depth usually costs less and reaches a higher R-value for the money. We say so when that is the case. Foam earns its price where space is tight, where moisture matters, or where air leaks are scattered through framing that batts cannot seal.
Curing and re-entry
Foam gives off fumes while it cures. HomeGuide advises staying out of the house for 24 hours or more after application. We plan the job so you know when to leave and when it is safe to come back.
Cold-weather limits
Foam needs minimum temperatures on the surface and in the air to stick and cure correctly. In a heated basement that is easy to meet in January. In an attic or an unheated garage it may mean waiting for a milder stretch or heating the space first. We put the plan for that in the quote.
Where We Use Foam
The spots where foam does a job other insulation cannot.
Rim joists and sill plates
Closed-cell sprayed into each joist bay to seal and insulate the band where the house meets the foundation.
Basement and crawl space walls
Closed-cell on concrete, block or stone walls before framing, or on walls that will stay open.
Sloped ceilings and knee walls
Foam in tight rafter bays in story-and-a-half houses and finished attics, where there is no room for depth.
Garages, shops and steel buildings
Closed-cell on steel or framing to stop condensation and hold heat.
Open walls during remodels
Foam in exposed stud bays when walls are open for a kitchen, bath or addition.
Air sealing in attics
Foam around chases, plumbing stacks and top plates before blown-in insulation goes on top.
Published Spray Foam Insulation Costs
| Job | Range and source |
|---|---|
| Spray foam, installed | $1.50 to $5.00 per sq ft (HomeGuide) |
| Open-cell / closed-cell | $1.50 to $3.50 / $3.00 to $5.00 per sq ft (HomeGuide) |
| About 1,000 sq ft | $1,500 to $5,000 (HomeGuide); $3,150 to $7,500 existing home (Fixr) |
| Existing walls / new construction | $3.15 to $7.50 / $2.75 to $6.50 per sq ft (Fixr) |
| All exterior walls | $4,000 to $10,000 (HomeGuide) |
| Whole house | $8,000 to $20,000 (HomeGuide); $10,000 to $30,000 (Fixr) |
| Typical job minimum | $1,000 to $2,000+ (HomeGuide) |
National ranges from HomeGuide's 2026 spray foam guide and Fixr (2025). Foam type, inches applied, access and prep set the actual cost, and small jobs often hit a minimum. We measure first, and the number on your written estimate is the price.
How a Foam Job Goes
1. Look and measure
We inspect the spaces, check for moisture and leaks, and measure the areas.
2. Written quote
Foam type, thickness, R-value and price for each area, plus any prep or removal.
3. Prep
Cover floors and belongings, mask fixtures, set up ventilation and close off the work area.
4. Spray
Apply in passes to the specified thickness, checking depth as we go.
5. Cure and clean up
Ventilate during curing, trim where needed, clean up and walk through the finished work with you.
Why Choose Us for Spray Foam Insulation
Thickness written down
You know how many inches go on each surface before we start.
Moisture checked first
We look for leaks and damp before covering anything with foam.
Straight talk on cost
If blown-in does the job for less, we tell you.
Spray Foam Insulation Questions
Which is better for a Duluth basement, closed cell or open cell?
Closed cell, in nearly every case. Basement walls and rim joists are cold and can be damp, and closed-cell foam slows vapor and does not absorb water. Open-cell can let warm indoor air reach the cold surface and cause condensation.
How long before I can go back in the house?
HomeGuide advises staying out for 24 hours or more while the foam cures. We will tell you the timing for your job, and ventilate the space while it cures.
What is cheaper, spray foam or regular insulation?
Blown-in and batts cost less per square foot; HomeGuide lists blown-in at about $1.00 to $2.80 per square foot against $1.50 to $5.00 for foam. Foam costs more because it also air seals. Many jobs use both: foam where sealing matters, loose fill on the open attic floor.
Does spray foam need to be covered?
Foam in living spaces generally needs a thermal barrier such as drywall, and the rules for attics and crawl spaces depend on how the space is used. We go over what your space requires before we quote it.
Spray Foam Insulation Service Areas
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Get a Spray Foam Insulation Estimate
Tell us which surfaces you want foamed. We will measure, check for moisture and send a written quote.