Spray polyurethane foam (SPF) is the dominant flat-roof system on Phoenix commercial properties under 50,000 sq ft, and for good reason. It is seamless, insulates at R-6.5 per inch, and reflects most of the sun when properly coated. It also fails predictably when the recoat schedule slips. Below is the recoat vs full removal decision as we run it on our commercial jobs.
How SPF actually degrades in Phoenix
The foam itself is fine. The coating on top is what fails. UV strips the elastomeric top coat at roughly 2 mils per year in Phoenix. Recoated at 20 to 25 dry mils, that gives you 5 to 7 years of protection. Miss the recoat and UV starts chewing on the foam itself, which is expensive to fix.
The recoat decision (60 percent of jobs)
- Foam is intact, no exposed yellow foam visible
- Blisters are fewer than 3 per 100 sq ft
- No wet-scan hits above 1 percent moisture content
- Recoat cost: $1.50 to $2.50 per sq ft for 20 mil silicone
Silicone vs acrylic top coat
For Phoenix we default to silicone. It shrugs off ponding water and holds reflectivity longer. Acrylic is 20 to 30 percent cheaper up front and fine on well-drained roofs, but do not use it where you have any low spot that holds water for more than 48 hours.
The recoat-plus-repair (25 percent of jobs)
Foam is mostly good but you have localized damage from HVAC service techs, satellite crews, or hail. We cut out the damaged foam, re-spray those areas, then recoat the whole roof. Adds $0.50 to $1.20 per sq ft to the recoat number.
The full removal (15 percent of jobs)
- Wet-scan shows more than 10 percent of foam saturated
- Foam has been un-coated for 3+ years and is chalky yellow
- Original foam is under 1 inch thick and R-value does not meet current code
- Owner is switching to TPO or PVC for warranty reasons
Full removal is $9 to $14 per sq ft for foam replacement, more if you upgrade to single-ply. This is where you protect the deck by not letting the recoat slip.
What we ask for before quoting a recoat
- Date of last recoat or original install
- Copies of any past invoices or warranty paperwork
- Roof access (interior stair or exterior ladder location)
- Any tenant work you want us to coordinate around
Need a real roofer to take a look?
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