Open cell spray foam costs roughly a third of closed cell and delivers R-3.6 to R-3.9 per inch plus a complete air seal. For attics and interior walls in Provo, Orem, and Utah County, it is usually the best value per dollar in insulation. Open cell foam is installed throughout Utah Valley by independent providers. Call (801) 691-7136 for a price range.
What Open Cell Foam Does
Open cell foam expands up to 100 times its liquid volume, filling every gap, seam, and wire penetration in a cavity before it cures soft and flexible. The open cell structure is what makes it cheaper and lighter than closed cell, and it adds a benefit closed cell does not have: sound dampening. Rooms insulated with open cell foam are noticeably quieter.
The air seal is the point. Air leakage can account for up to 40 percent of a home’s energy loss, and fiberglass does nothing to stop it. Open cell foam stops it completely in the cavities it fills.
How It Is Used in Utah County Homes
- Attic roof decks. Foaming the underside of the roof brings ducts and HVAC equipment inside the conditioned space. See our attic insulation page for the full comparison.
- Interior walls. For sound control between bedrooms, bathrooms, and home offices.
- Above-grade exterior walls in new construction and additions.
How Deep Does Open Cell Foam Need to Be?
Open cell delivers R-3.6 to R-3.9 per inch, so depth is what gets you to a target R-value. These are the assemblies that matter in Utah County under the 2021 IECC, climate zone 5:
| Assembly | Code R-value | Open cell depth | Closed cell depth |
|---|---|---|---|
| Vented attic / ceiling | R-49 | 13 to 14 inches | 7 to 8 inches |
| Unvented roof deck (5B / 6B) | R-26 | about 7 inches | about 4 inches |
| Floor over crawl space | R-30 | 8 to 9 inches | 4 to 5 inches |
Open cell is the value choice wherever there is depth to work with and no moisture risk, which in practice means attics and interior walls. Where space is tight or the foam will contact concrete, closed cell is the correct product instead. The full code breakdown, including the conditions on the unvented pathway, is on the attic insulation page.
Open Cell Pricing FAQ
How much does open cell spray foam cost?
Open cell spray foam typically costs $0.45 to $0.75 per board foot installed. A board foot is one square foot of foam at one inch deep. A full attic roof deck in an average Utah County home usually lands between $3,000 and $7,000 depending on roof area and foam depth.
Open cell or closed cell, which do I need?
Simple rule: moisture risk or tight space means closed cell. Big open cavities above grade mean open cell. A phone call can usually narrow down which one fits your project in two minutes.
Does open cell foam meet code in climate zone 5?
Yes, with the right depth. Utah County is climate zone 5, and open cell reaches required R-values with roughly 10 to 14 inches at the roof deck. Because it expands so much, filling deep rafter bays is exactly what it is designed for.