Thickness recommendations for North Texas attics, walls, metal buildings, and crawl spaces.
The ideal spray foam thickness depends on the foam type, the assembly location, the target R-value, and the specific climate demands of your building. In Dallas–Fort Worth, the long cooling season makes correct thickness especially important.
For most DFW shingle-roof conditioned attics, Texas Foam Pro typically recommends 5.5 inches of open-cell spray foam applied directly to the underside of the roof deck.
At approximately R-3.7 per inch, this delivers roughly R-20 thermal performance at the roofline, which is highly effective in North Texas when the goal is to bring attic ductwork and mechanical systems inside the conditioned envelope.
In Dallas–Fort Worth, the real performance gain comes not just from R-value, but from air sealing the roof deck and dramatically reducing attic temperatures that can otherwise exceed 140°F in summer.
The ideal depth may still vary slightly based on:
For most standard DFW homes, 5.5 inches is the sweet spot for performance, efficiency, and long-term ROI.
Closed-cell in attic applications typically ranges from 3 to 5 inches. At R-6.5 per inch, 5 inches delivers about R-32, adequate for most conditioned attic applications where duct protection is the primary goal.
Crawl space perimeter walls: typically 2 to 3 inches of closed-cell to achieve vapor control and adequate R-value.
Rim joists: 2 inches of closed-cell is the most common specification, providing both air sealing and vapor resistance at this vulnerable edge condition.
Texas Foam Pro evaluates your specific framing, HVAC location, and climate exposure to design the right depth for your structure.