Closed-cell SPF creates a seamless, fully-adhered, insulating layer that stops leaks and adds R-value across the entire roof — sprayed in place over your existing system in most cases.
Spray polyurethane foam is applied as a liquid and expands in place into a closed-cell monolithic layer across the whole roof. Because it is sprayed rather than rolled out in sheets, there are no seams, joints or fasteners for wind and water to attack — it self-flashes around every HVAC curb, pipe, drain and parapet.
The foam is then topcoated, most often with silicone, which carries the UV protection and the reflectivity. The foam does the insulating and the waterproofing geometry; the coating protects the foam and is what gets renewed over time.
Closed-cell SPF delivers roughly R-6.5–7 per inch as one continuous, seamless layer — no gaps and no thermal bridging. Polyiso board is labeled near R-6 per inch but ages toward roughly R-5.5 (LTTR), loses R-value in the cold, and bleeds heat at every fastener and board seam.
Continuous insulation plus a reflective topcoat lowers rooftop surface temperatures, which cuts cooling load and HVAC runtime year-round.
Fully-adhered SPF has tested past the limits of UL equipment and beyond 900 psf in FM pull testing — roughly 7–15× a mechanically-attached membrane. FEMA ranks SPF among the best-performing systems in major storms.
Mechanically-fastened membranes fail at seams, edges and fasteners; FM data shows roughly 3.5× more edge-zone failures once winds pass 90 mph. That difference matters in a Florida wind zone.
SPF over an existing roof is only possible on a sound, dry deck. Any area of insulation reading over 15% moisture must be removed and that section repaired (or foamed back in) before the rest of the roof can be coated.
If more than 50% of the roof is holding 15% moisture or higher, the full roof must be torn off and replaced — and an SPF system is an ideal replacement, installed directly over the deck when needed.
Every commercial roof project requires a third-party moisture reading and engineering report before we provide a final price.
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A spray foam (SPF) roof installed over an existing commercial roof starts at $7 per square foot in Florida and typically runs up to $10, including removal of wet insulation and a silicone topcoat. Applied to a bare deck after a tear-off, it is priced as a replacement, which starts around $12 per square foot. Access and building height (over three stories may need a crane or lift) move the price. Roof King's free roof cost calculator (roofkingus.com/roof-cost-calculator) measures your roof and prices it for your building.
The oldest performing SPF roofs are over 50 years old. Because the physical properties of SPF change little with age, how long the SPF roof system lasts depends on the original application and long-term maintenance.
SPF has excellent adhesion to a variety of substrates including concrete, tectum, gypsum, BUR, and metal. Since SPF adds little weight, it can be applied in varying thickness to add slope and fill in low areas.
SPF delivers continuous insulation with no thermal bridging, and the reflective silicone topcoat lowers rooftop surface temperatures — cutting cooling loads and HVAC runtime year-round.
Usually not. SPF bonds directly to most existing commercial roofs. A tear-off is only required when the third-party moisture survey shows more than 50% of the roof holding 15% moisture or higher.
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