There are a number of advantages to foam. Polyurethane foam typically has an insulation value of approximately R-5 per inch, most other roofing materials have little to none. Foam roofs are easily repaired when damaged, either by organic debris or careless tradesman that may be working on roof top equipment. Foam will last virtually indefinitely when it is properly maintained, mainly ensuring that the roof has sufficient elastomeric coating.
Polyurethane foam is highly susceptible to the damaging UV rays from the sun. After only 24 hours of exposure the foam begins to degrade and turn to powder. Because of this it is critical that foam roofs be coated with a latex or silicone or urethane coating. Generally speaking the minimum coating that will protect the foam is 9 dry mil thickness. Most manufactures require a minimum of 27 dry mils to issue a warranty to the home owner. This thickness will typically last from 5 to 7 years before a re-coat is necessary. Heavier applications of elastomeric coating will result in longer intervals between re-coats.
The simple answer is no. The surface of the foam will turn to a powder when exposed to the sun. If you try to re-coat with this condition the elastomeric coating will not have an adequate substrate to hold on to. While the installation may look fine in the short term, it will ultimately begin to peel and flake off. If the powdery area is small, it can be ground down to good foam and either new foam added or simply re-coated. If the area is large generally it is not cost effective to do this and the foam must be completely removed and re-foamed then coated.
A Flat Roof is actually called a low sloped roof. That is a roof with a pitch that is a minimum 1/4 inch per ft and commonly used on structures with low sloped roof designs or porches and patios. For roof slopes that are truly flat or don’t meet the minimum 1/4 inch per ft pitch, a tapered system design would be required to create the 1/4 inch per ft minimum to ensure properly water drainage off the roof. For roof slopes that are truly flat or don’t meet the minimum 1/4 inch per ft pitch, a tapered system design would be required to create the 1/4 inch per ft minimum to ensure properly water drainage off the roof.