Closed-cell and open-cell foam
Spray Foam Insulation in Cullman, AL
The right foam for each surface, at a thickness written on the quote.
- Free on-site estimates
- Written quotes with material, thickness and R-value for each area
- Crawl space moisture and roof leaks checked before we insulate
Picking the Right Foam
Spray foam insulation goes on wet, expands to fill gaps, and cures in place, so it insulates and air seals in a single layer. In Cullman County homes and farm buildings, that seal matters both in July, when humid air pushes in, and in January, when cold air leaks through floors and walls. We spray two kinds of foam, and choosing between them is the first decision on every job.
Closed cell vs open cell
Closed-cell foam cures hard and dense. HomeGuide rates it at R-5 to R-7 per inch, and at normal thickness it slows water vapor and does not soak up water. It adds stiffness to what it is sprayed on. Open-cell foam is lighter and softer, expands much more, and rates about R-3.5 to R-3.7 per inch. It seals air well and dampens sound but lets vapor through.
In north Alabama, closed-cell goes where moisture and cold meet: crawl space walls, rim joists, the underside of floors, and steel. Open-cell goes under roof decks when sealing an attic, and in above-grade walls and floors between rooms.
Sizing to zone 3
Cullman County is in climate zone 3A. Alabama's code summary lists R-20, or R-13 plus R-5 continuous, for wood-frame walls in zone 3, and R-13 or R-5 continuous for crawl space walls. Closed-cell reaches R-13 in about 2 to 2.5 inches, which suits crawl space walls and rim joists. In a 2x4 wall, closed-cell can reach higher R-values than batts can in the same depth.
Where we use foam most
The rim joist, the wood band sitting on top of the foundation wall, is one of the leakiest parts of a house with a crawl space. Closed-cell sealed there stops drafts along the whole perimeter. Above that, we foam the floors of rooms over garages, kneewalls by upstairs bonus rooms, and roof decks in vaulted ceilings or sealed attics. In steel buildings, foam on the panels stops condensation.
What foam is not for
Foam does not fix a leak. A roof, window or plumbing leak needs to be repaired first. Foam should not cover old wiring or vermiculite until they are checked. On a wide-open attic floor, sealing the gaps and blowing loose fill to depth usually costs less than foam.
Prep and curing
We cover and mask, ventilate, and confirm the space is warm enough to spray. HomeGuide advises staying out for at least 24 hours while foam cures. For a detached shop or barn, that may not affect the house at all. Get a free estimate
Where Spray Foam Goes
Common foam work in Cullman County homes and buildings.
Closed-cell foam
R-5 to R-7 per inch (HomeGuide); crawl space walls, rim joists, floors and steel.
Open-cell foam
R-3.5 to R-3.7 per inch; roof decks and above-grade walls.
Rim joists
Sealing the band above the foundation where drafts enter.
Floors over garages
Foam in the floor framing of bonus rooms.
Vaulted ceilings
Closed-cell under the roof deck where there is no attic.
Steel buildings
Foam on barn, shop and poultry house steel to stop drip.
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 guide and Fixr's 2025 guide. Foam type, thickness, access and prep change the total, and small jobs often hit a minimum. The figure on your written estimate is what you are charged.
How a Spray Foam Job Runs
1. Visit
Inspect for leaks, damp wood, wiring and vermiculite; measure each space.
2. Written quote
Foam type, thickness, R-value and price by area.
3. Prep
Cover, mask, ventilate, check temperature.
4. Spray
Apply in passes to the planned thickness; trim as needed.
5. Walk-through
Clean up and tell you when the space is ready.
Why Choose Us for Spray Foam Insulation
Foam where it pays
If loose fill does the job for less, we say so.
Thickness written
Thickness and R-value appear on every line.
Problems flagged
Leaks, wiring and pests are named before foam covers them.
Spray Foam Insulation Questions
How much does closed-cell spray foam cost per square foot?
HomeGuide lists closed-cell at $3.00 to $5.00 per square foot installed at common thicknesses. Thicker foam costs more. We write the thickness and price on the quote.
Is closed-cell worth it in a crawl space?
Usually yes, because it does not soak up water and slows vapor. Open-cell is not a good choice in a damp crawl space.
Can spray foam be installed in winter?
Yes in heated spaces. Cold crawl spaces, attics and barns need the surface and foam within a working temperature range, so we add heat or pick a milder day.
Does spray foam stop moisture?
Closed-cell slows vapor and keeps humid air off cold surfaces. It is not waterproofing and does not fix leaks.
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Get a Spray Foam Insulation Estimate
Tell us the spaces and what you have noticed. We will send a written foam plan and price.