The foam itself is indefinite — it doesn't degrade. The protective topcoat needs renewal every 10–15 years, making the system effectively permanent.
The most efficient option available. R-6.5 per inch with zero thermal bridging means dramatically lower HVAC costs compared to any other commercial system.
Usually yes. SPF can be sprayed over BUR, metal, single-ply, and concrete — eliminating tear-off costs and landfill waste.