What Is Open Cell Spray Foam?
Open cell spray foam is a soft, flexible insulation material that expands dramatically upon application — filling wall cavities, ceiling spaces, and gaps with a continuous air barrier. Unlike closed cell foam, the cell structure remains "open," meaning air can move through the cured foam. This makes it lighter, more flexible, and less expensive per square foot.
Open cell foam achieves an R-value of approximately R-3.5 to R-3.7 per inch, making it ideal for applications where you're filling larger cavities and don't need the extreme density of closed cell foam.
Best Applications for Open Cell Foam in St. George
Open cell spray foam is the right choice for several common applications throughout Washington County homes and buildings:
- Interior walls & partition walls — Significantly reduces room-to-room noise transfer, a major benefit in open-plan homes and multi-room buildings.
- Vaulted ceilings — Fills irregular shapes and cathedral ceiling spaces that fiberglass batts can't properly cover.
- Basement walls & crawl spaces — Where moisture isn't a primary concern, open cell foam provides excellent insulation in below-grade applications.
- Interior attic spaces — When sprayed from the interior against roof decking, open cell foam is effective and more affordable than closed cell for larger attic volumes.
- Sound studios, home theaters, bedrooms — The open cell structure absorbs sound waves better than rigid materials, making it a preferred acoustic insulation.
- Around plumbing and wiring penetrations — Spray foam is the only insulation that truly seals around irregular shapes and utility penetrations.
Open Cell vs. Closed Cell: Which Is Right for You?
This is the most common question we get from St. George homeowners. Here's a straightforward comparison:
| Feature | Open Cell | Closed Cell |
|---|---|---|
| R-value per inch | R-3.5 – R-3.7 | R-6.0 – R-6.5 |
| Moisture resistance | Low (permeable) | High (vapor barrier) |
| Sound dampening | Excellent | Good |
| Structural strength | None | Adds rigidity |
| Cost per sq. ft. | Lower | Higher |
| Best for | Interior walls, sound, large cavities | Attics, exteriors, metal buildings |
For many St. George projects, the best approach is a combination: closed cell on exterior-facing surfaces (attic, exterior walls) and open cell for interior partitions and sound control. We'll help you determine the right mix for your budget and goals.
Open Cell Spray Foam Cost in St. George, UT
Open cell spray foam typically costs $0.44–$0.65 per board foot installed in the St. George area. For a typical 2,000 sq. ft. home with 2×4 walls, open cell spray foam for all exterior walls runs approximately $1,800–$3,500 depending on wall height and existing insulation conditions.
Attic applications using open cell foam (spraying the roof deck from below) typically run $2.50–$3.50 per sq. ft. of attic floor space.
The best way to get accurate pricing is a free on-site estimate — every home is different.
Why Choose a Local St. George Contractor
National companies and statewide franchises don't know Washington County the way local contractors do. Southern Utah has specific climate challenges — 105°F+ summers, monsoon season humidity spikes, and high UV exposure — that affect the right approach to insulation. We've been doing this work in this desert climate and know what lasts and what doesn't.
What to Expect on Installation Day
- Pre-job walk-through — We review the scope, confirm access points, and cover any surfaces that need protection.
- Surface prep — Existing materials removed if needed; surfaces cleaned and dried.
- Foam application — Our technicians apply foam in passes at the correct thickness, allowing each pass to expand and cure before the next.
- Trim & cleanup — Excess foam is trimmed flush to framing. We clean the work area thoroughly before leaving.
- Cure time — Open cell foam reaches tack-free in minutes and is fully cured within 24 hours. Most homes can be reoccupied the same day.
Service Areas for Open Cell Spray Foam
We install open cell spray foam throughout Washington County including: St. George, Washington, Hurricane, Santa Clara, Ivins, La Verkin, Toquerville, Leeds, and Springdale. We also serve Cedar City and Enoch in Iron County.