No we do suggest a flash coat over epdm sometimes depending on the age of the roof the solvents may cause the product will bubble during the drying process which is perfectly normal. Although they will go down it might seem scary at first to the consumer that is why we suggest the flash coat you won't have that bubbling. It is actually a great benefit of the product. What is occurring is the solvent is forcing up to the surface all the trapped air. so as the product dries what you have left is an air tight seal between the coating and your roof.. Other coating will have trapped air between the coatings and the roof. That is why other coatings have a tendency to crack after a few year.