It is not exposed to bulk water
Open cell is vapour permeable. That is useful in the right place and a liability in a wet crawl space or against a below-grade wall. Those get closed cell.
Material guide
Open-Cell Spray Foam Insulation
Open cell is the lighter of the two foams. It expands further, it fills awkward framing well, and it is the usual choice inside a conditioned space. It is not the answer everywhere, and we will say when it is not.
15+ years Family owned and operated7 days Open 7 days, 7:00 AM to 8:00 PMFree Estimates
Free Insulation Estimate
Family ownedOperating since 2010
Spray foam specialistsNot a general insulation reseller
Two crews, two statesNorth Georgia and North Alabama
Lawrenceville based1891 Prospect Church Road
Where it earns its place
The jobs open cell is usually right for.
Open cell is not a cheaper substitute for closed cell. They do different things, and the assembly decides which one belongs.
01
Tell us what you are noticing →Conditioned roof decksBringing an attic inside the thermal boundary, where the foam is never exposed to bulk water.
02Interior walls and framed cavitiesIt expands into the gaps around wiring, plumbing and blocking that cut material misses.
03Rooms where noise mattersIt dampens airborne sound within the assembly. Useful, but it is not a soundproofing system.
04Retrofits with irregular framingOlder framing is rarely square. Foam does not need it to be.
Before we specify it01 02 03
What has to be true for open cell to be the right call.
Foam that is specified against the wrong assembly causes problems that are expensive to reach later. These are the checks.
There is room to expand
It grows substantially on application. Framing depth and the finished surface both have to accommodate it.
The air boundary is clear
We agree where the thermal and air boundary is meant to sit before anything is sprayed, because moving it afterwards means opening the assembly again.
The material decision
Open cell against closed cell.
This is the decision on most jobs. Neither is better. They suit different conditions.
Lighter, expands further
Open-cell spray foam
- Usually fits
- Conditioned roof decks, interior walls and framed cavities inside the building envelope.
- We check first
- Expansion room, framing depth and that it will never meet standing water.
Denser, adds rigidity
Closed-cell spray foam
- Usually fits
- Crawl spaces, rim joists, metal buildings and anywhere moisture and structure both matter.
- We check first
- Substrate condition, the thickness the application calls for and clearance for other trades.
How the job runs
How we decide, and how it gets installed.
The material is chosen against the assembly. That decision happens at the estimate, in writing.
- 01We look at the assembly
Framing, depth, what the space connects to and where the boundary should sit.
- 02We specify the foam
Open cell, closed cell, or both in different areas of the same job. Mixed scopes are normal.
- 03You get it in writing
Which surfaces, which product, what preparation and what is excluded.
- 04We install it and stand behind it
The crew that quoted the work is the crew responsible for it.
Open-cell spray foam FAQs
The things owners usually want settled before they book an estimate.
What is the difference between open-cell and closed-cell spray foam?
Open cell is lighter and expands further, and it lets vapour through. Closed cell is denser, adds rigidity to the assembly and resists moisture. That is why open cell suits conditioned interior assemblies and closed cell suits crawl spaces, rim joists and metal buildings. The assembly picks the product, not the budget.
Is open cell worse than closed cell?
No. It is different. Specifying closed cell everywhere because it sounds stronger costs more and is not always better for the assembly. Specifying open cell where water can reach it is a genuine mistake. Getting that decision right is most of what an estimate is for.
Does open-cell foam absorb water?
It is vapour permeable, which means moisture can pass through it rather than being trapped at the surface. In an interior assembly that is often desirable. In a place that sees bulk water it is the wrong product, which is why we do not use it in crawl spaces.
Will it help with noise?
It does dampen airborne sound within the assembly and people commonly notice it in a bonus room or a bedroom. It is a useful side effect rather than a soundproofing system. If noise is your main goal, tell us during the estimate, because the assembly matters more than the foam.
How thick does it need to be?
That depends on the assembly, the climate zone and what the code requires for your specific application. Anyone quoting a thickness before seeing the building is guessing. We state it in the written scope for your job.
Related work
Other parts of the building worth checking.
Insulation problems rarely stay in one place. These are the areas that most often come up alongside this one.
North Georgia · North Alabama
Not sure which foam your building needs?
That is the question the estimate answers. Tell us what you are insulating and where it is.