Modified membranes are designed to be installed over an approved surfacing fastened to specific guidelines. If modified membranes are installed over a surface without the proper fastening the manufacturer’s warranty is voided and the roof assembly is out of code. This also leaves the roof susceptible to roof blow-off in the event of strong winds. After Hurricane Andrew in 1992 our code system was completely redesigned. In 1994, when this new code system was introduced, the requirements became much more strict. They increased again after hurricane Charley left hundreds of modified roofs sitting in the street as the entire system uplifted all in one layer. However, most of the good roofing contractors go above code and install more fasteners than required due to lessons learned after the storms.