Materials
Open-Cell Spray Foam Insulation
The lighter of the two foams. It seals air, damps sound, and lets a roof leak show itself on the ceiling below.
Free on-site assessment across the eight-county Houston-Galveston region. Monday to Saturday.
The material
What open-cell actually is
Open-cell foam expands to many times its liquid volume and cures into a soft, low-density material whose cells stay partly open. Air stops at it, which is what makes it an air barrier. Water vapor still passes through it, and that turns out to matter.
It is the foam most often specified at an attic roofline, in interior partitions where sound is the goal, and in wall cavities on residential work where bulk water never reaches the assembly. Where water can reach it, closed-cell is the material that belongs there instead.
Both foams are made the same way, from two liquids that meet in the gun and react. The A-side and B-side page covers the chemistry, including why ratio, temperature and pass thickness decide whether what you paid for performs.
Where it belongs
Four places open-cell is the right call
Open-cell earns its place where the job is sealing air and damping sound, and where the assembly needs to stay able to dry. It is the cheaper of the two foams per square foot, which is part of why it covers more of a house.
- 01 Attic rooflinesThe most common residential use in Houston, and the one that brings ductwork in out of the heat.
- 02 Interior walls and floorsBetter at damping airborne sound than closed-cell, because it is softer and less dense.
- 03 Wall cavities on a dry assemblyWhere bulk water stays out of the assembly and cost per square foot matters.
- 04 Where you want a leak to showVapor-open, so water from a roof leak travels through and appears on the ceiling instead of sitting hidden against the deck.
Where it does the wrong job
Four places to specify something else
Saying this plainly is more useful than another list of benefits.
Against a steel panel
The panel has to stop being an exposed cold surface, which takes closed-cell.
Why steel needs closed-cellCrawl spaces and rim joists
Anywhere bulk water contact is possible, closed-cell is the material that sheds it.
How a crawl space is scopedBelow grade
Outside what this material is built for. Closed-cell handles ground contact.
Where closed-cell belongsWhere rigidity is wanted
Closed-cell stiffens the assembly it bonds to. Open-cell leaves the structure as it found it.
Closed-cell in detailStraight comparison
Open-cell against closed-cell
Two tools for two jobs. Most Houston houses want one of them at the roofline and possibly the other somewhere else.
| What changes | Open-cell | Closed-cell |
|---|---|---|
| Density | Light and soft | Dense and rigid |
| Air sealing | Yes | Yes |
| Vapor | Vapor-open, so water passes through | Sheds bulk water |
| Sound damping | Open-cell leads here | Closed-cell trails |
| Adds rigidity | Leaves the structure as it found it | Stiffens what it bonds to |
| Cost per square foot | Lower | Higher |
| Typical Houston use | Attic rooflines, interior partitions | Rim joists, crawl spaces, steel buildings |
General material properties, not a performance claim about a specific product. We will give you the manufacturer datasheet for whatever we propose for your building.
Related
Where open-cell gets used
Attic Insulation and Air Sealing
The most common home for open-cell in this climate, and the decision that turns on where your ductwork runs.
Attic assemblies explainedClosed-Cell Spray Foam
The other half of the comparison, and the answer wherever water, steel or rigidity are involved.
Where closed-cell belongsBlown-In Insulation
Cheaper per square foot, and the better buy when the ducts run inside conditioned space.
When blown-in winsQuestions
Asked about open-cell
It is the different one. On an attic roofline in Houston it is usually the better choice, partly because a leak in the roof above it shows itself on the ceiling instead of sitting hidden against the deck for two years.
It absorbs and releases water rather than shedding it, which is exactly why crawl spaces, rim joists and anywhere bulk water can reach take closed-cell instead.
There is an odor during application and cure. We give you the manufacturer's re-entry time for the specific product before the day, so you can plan around it. The safety and re-entry page covers how the work area is isolated.
The applied depth is written on the scope in inches before anything is ordered, and it is verified with a gauge as the work goes. Depth is what decides whether the job performs, so it belongs in writing.
The visit is free. Someone comes out, looks at the building and gives you a written scope and a price, and the decision stays yours.
48 cities across the eight-county Houston–Galveston region — Harris, Fort Bend, Montgomery, Brazoria, Galveston, Chambers, Liberty and Waller — plus five extended project markets.
It depends on the product and the thickness. For scale, a Department of Energy Building America photo shows a cathedral ceiling with 3 inches of closed-cell foam (R-19) and 7.5 inches of open-cell foam (R-28) sprayed together below the roof sheathing. The product's technical data sheet gives the tested value per inch, and our scope states the applied depth.
For an attic roofline in a house, we use open-cell. Our main open-cell foam is Accufoam AF1, and we also spray Profoam ProFill. The Department of Energy describes open-cell as lighter and less expensive than closed-cell. Closed-cell goes where water contact is possible: rim joists, crawl spaces and steel buildings.
Free assessment
We will tell you which foam your building wants
And why, in writing, with the applied depth on it. One visit, a written scope, and a written price.
(832) 737-078748 cities across the eight-county Houston-Galveston region, plus five extended project markets.