Open cell spray foam is a soft, lightweight foam that expands as it is sprayed and fills every gap in a wall or roof cavity. It insulates, seals air leaks and absorbs sound in one layer, and it costs less per inch than closed cell foam.
CAL FOAM Inc. installs open cell foam in house walls, attic roof lines, cathedral ceilings and interior walls across Tulare County and the Central Valley. California contractor license #1123937.
California's climate is anything but uniform. Bakersfield summers push past 110°F. San Jose mornings can be damp and cool even in July. Santa Barbara deals with coastal humidity while Fresno sits in a Central Valley heat trap. Managing indoor comfort across this range of conditions requires insulation that does more than slow down heat — it needs to seal your building, manage moisture, and deliver consistent performance year after year.
Open-cell spray foam insulation is one of the most effective tools available for doing exactly that. At CAL FOAM Inc., we specialize in professional open-cell spray foam installation for homes, commercial buildings, and agricultural structures throughout California. We are a licensed, owner-operated contractor based in Strathmore — License #1123937 — and we bring hands-on expertise to every project we take on.
Open-cell spray foam is a two-component insulation material that expands on contact with the surface it is applied to. As it expands, it forms a structure of tiny, interconnected cells — hence the name "open-cell." These cells are not sealed, which gives the material a soft, sponge-like texture and makes it highly effective at absorbing and damping sound.
Unlike fiberglass batts that simply fill a cavity, open-cell spray foam bonds to the surface it is applied to and expands to fill every gap, seam, and irregularity. This creates a continuous, seamless insulation layer with no cold bridges or air leakage pathways. The foam has an R-value of approximately R-3.7 per inch, which is lower per inch than closed-cell foam but still significantly outperforms fiberglass batts in real-world performance because of its superior air sealing.
Both types are spray foam, but they behave very differently:
CAL FOAM Inc. installs both types. During your free assessment, we will recommend the right product — or combination of products — based on your building's specific needs.
|
Space |
Usual choice |
Why |
|
House walls |
Open cell |
Seals and insulates at a lower cost per inch |
|
Attic roof line over a home |
Open cell, in most homes |
Seals the attic and fills deep rafters for less. We check your roof and climate zone first. |
|
Cathedral and vaulted ceilings |
Either |
Closed cell when the rafters are shallow and you need more R-value in less space |
|
Interior walls, bedrooms, home offices |
Open cell |
Absorbs sound |
|
Metal shops, garages and barns |
Closed cell |
Stops condensation on metal |
|
Crawl spaces and mobile home underbellies |
Closed cell |
Does not soak up water |
Many jobs use both: closed cell on metal and in damp spaces, open cell inside the home. See the full side-by-side comparison on our closed cell spray foam page.
Open cell foam left exposed in a room you live in needs a cover: drywall, or a tested intumescent coating, which we also apply.
Ready to take the next step? Call CAL FOAM Inc. at (805) 225-3626 or visit calfoaminc.com to schedule your free on-site assessment. We serve Strathmore, Bakersfield, Fresno, Los Angeles, Sacramento, San Jose, Stockton, Anaheim, Riverside, Modesto, Turlock, Santa Barbara, San Luis Obispo, Paso Robles, Lancaster, Victorville, Napa, Santa Rosa, Redding, and communities across California. License #1123937.
Open-cell spray foam delivers approximately R-3.7 per inch. California's Title 24 energy code requires R-13 to R-21 for walls and R-30 to R-49 for attics depending on climate zone. At 3.5 inches thick (standard stud cavity), open-cell foam achieves approximately R-13. For higher R-value targets, we can increase thickness or recommend a hybrid approach with closed-cell foam on the exterior face of the cavity. Open-cell foam consistently outperforms rated R-values in real buildings because of its air sealing, which fiberglass at the same nominal R-value cannot match.
Yes. Once fully cured — within 24 hours of application — open-cell spray foam is chemically inert and does not release harmful compounds. During installation, applicators use proper PPE and ensure adequate ventilation. Occupants should stay clear of the work area during spraying and for a few hours afterward. All products used by CAL FOAM Inc. comply with California VOC regulations and relevant health and safety standards.
In some cases, yes — using injection techniques through small access holes. However, open-cell spray foam is most effectively installed in open wall cavities during new construction or renovation when walls are exposed. For existing closed walls, we assess the situation during our site visit and recommend the most practical approach, which may include open-cell injection foam or other retrofit solutions.
No — open-cell spray foam is vapor-permeable, not a vapor barrier. In many California climate zones, this is actually the preferred approach because walls need to be able to dry if they get wet. If a vapor barrier is required for your specific wall assembly or climate zone, closed-cell spray foam is the appropriate choice. We will advise you on the right vapor management strategy for your building during the assessment.
A typical residential attic or wall cavity project takes one to two days. Larger or more complex buildings take longer. We provide project timelines during the estimation phase, and we work to minimize disruption to your household or business operations.
Yes, meaningfully. Wildfire smoke enters buildings primarily through air infiltration — the same gaps and cracks that open-cell spray foam seals. Homes with tighter building envelopes from spray foam insulation consistently show lower indoor smoke concentrations during wildfire events compared to homes insulated with fiberglass batts. This is an increasingly important consideration for California homeowners.
Pricing depends on the square footage being insulated, the application thickness required for the target R-value, the accessibility of the space, and any preparation work needed. We do not provide reliable quotes over the phone — the variables matter too much. Contact us for a free on-site assessment and written estimate.
It depends on the target for your project. A filled 2x4 wall reaches about R-12 to R-13 and a filled 2x6 wall about R-19 to R-21. Title 24 targets change by climate zone and by whether the job is a new build or a remodel, so we check your target before we set the depth, and add closed cell where open cell alone cannot reach it in the space available.
For an attic over a home, open cell on the underside of the roof is often the better value: it seals the attic and fills deep rafters for less. Closed cell is the better choice where the rafters are shallow, where there is moisture, or under a metal roof. We recommend one after we see the attic.
It cuts airborne noise such as voices, TV and traffic, because its soft cells absorb sound. It does less for impact noise such as footsteps. For the quietest rooms, foam the interior walls as well as the outside ones.
Spray foam needs open framing, so finished walls have to be opened first. The best time is during new construction, an addition or a remodel, when the walls are already open.
In rooms you live in, yes. Code requires a thermal barrier such as drywall, or a tested intumescent coating, which we also apply.
Once it has fully cured, yes. Everyone stays out during spraying and for the re-entry time the foam maker sets, and we tell you when it is safe to go back in.
The price depends on the area, the depth and how easy the space is to reach. Open cell costs less per inch than closed cell. We give free written quotes after we see the space.
Call (805) 225-3626 or email derek@calfoam.net to set up a free on-site visit. CAL FOAM Inc. is based at 19308 Orange Belt Dr, Strathmore, CA 93267, and serves Tulare County and the Central Valley. California contractor license #1123937.
Related services: Closed Cell Spray Foam, Attic Insulation, Residential Insulation, Intumescent Fire Coating