Open-cell or closed-cell spray foam: which do I need?
For most shops, pole barns, metal buildings and crawl spaces, closed-cell. It gives roughly R-6 to R-7 per inch, resists moisture and bonds to metal. Open-cell runs roughly R-3.5 to R-3.8 per inch and lets water vapor pass, which suits some specific assemblies. Closed-cell is Empire's main offering; open-cell is available for a specific project.
The short comparison
Closed-cell foam is dense and rigid. It runs roughly R-6 to R-7 per inch and, at the thickness the product calls for, acts as a vapor retarder, meaning it slows moisture moving through the wall or roof. Open-cell foam is soft and light. It runs roughly R-3.5 to R-3.8 per inch and lets water vapor pass through. These are general ranges; real numbers come from the product's documentation.
Because open-cell holds less per inch, it needs more depth to reach the same insulation level. In a shallow wall cavity or against a thin metal panel, that depth is often the deciding factor.
Where closed-cell earns its place
Pick closed-cell where space is tight or moisture is the worry: shop and garage walls, pole barns, metal buildings and crawl spaces. In a North Idaho winter, warm, moist air inside meets cold steel and condenses. Closed-cell sprayed against the panels stops the air and the vapor drive that carry moisture to the cold steel, which fiberglass can't do.
That's why 2-lb closed-cell and HFO closed-cell are Empire's main offering and what Nick sprays himself on most jobs. Know the limits too: closed-cell resists moisture but isn't waterproofing, and it won't fix a roof leak or stand in for drainage or ventilation.
When open-cell is the right call
Open-cell fits where the assembly is designed for a vapor-open foam. Neither foam is right for every wall or roof, so the choice should come from your building, not from habit. Empire can provide open-cell for a specific project, but generally doesn't spray it.
If someone recommends open-cell for your building, ask why, and bring that answer to Nick when you call. When you compare quotes, an open-cell price and a closed-cell price only line up if they reach the same insulation level over the same surfaces.
Related questions
Which foam does Empire use on shops and pole barns?
Closed-cell, in 2-lb or HFO closed-cell. It's denser, gives more insulation per inch and resists moisture, which suits thin metal walls and roofs. Open-cell can be provided for a specific project, but closed-cell is Empire's standard for shops, barns and metal buildings.
Will closed-cell foam stop condensation in my metal building?
Closed-cell foam is how Nick deals with it. Sprayed against the panels, it stops the warm, moist air and the vapor drive from reaching the cold steel, which is what makes it drip. It won't stop every source of moisture. Sort out roof leaks and drainage first.
Is an open-cell quote comparable to a closed-cell quote?
Only if both reach the same insulation level over the same surfaces. Open-cell needs more depth for the same R-value, so compare what each quote delivers, not just the total. Ask for the foam type and installed thickness on every surface.
Do both foams need to be covered?
In occupied space, usually yes. Both are combustible, so codes generally require an approved thermal barrier, such as 1/2-inch gypsum drywall, between either foam and occupied space. Some attics and crawl spaces allow an ignition barrier or a tested assembly instead. Our thermal barrier answer page covers the details.
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Services
- Closed-Cell Spray FoamMore insulation per inch than open-cell foam, with greater resistance to water vapor. Useful where cavity depth is limited or moisture control matters.
- Shop & Garage InsulationReduce heat loss and drafts in a shop or garage you plan to heat. Foam type and coverage depend on the building and how you use it.
- Pole Barn InsulationInsulate pole barn walls and roofs to reduce heat loss and help manage condensation. The plan should account for ventilation and how the space will be used.
- Crawl Space InsulationSeal air leaks at crawl space walls and rim joists to help with drafts and cold floors. Drainage and ground moisture need their own plan.
- Attic InsulationReduce heat loss through the top of your home. Roof-deck and attic-floor insulation are different approaches; the right choice depends on ventilation and moisture control.
- New Construction InsulationInsulate accessible walls and roof cavities before finishes go in. Plan the foam type, thickness and installation stage with your builder.
- Commercial InsulationInsulation for workspaces, warehouses and other commercial buildings. Plan access, ventilation and time out of the work area before installation.
- Metal Building InsulationClosed-cell foam can help manage condensation on metal panels and reduce heat loss. Surface condition, ventilation and building use guide the installation plan.
- Retrofit InsulationAdding spray foam to existing homes and buildings during remodels, re-roofs or when walls and ceilings are open.
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Request an estimate online. Nick handles your estimate himself.
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Request your free estimate
Request an estimate online. Nick handles your estimate himself.