The most important aspects of curb details are that they are designed at the proper height and there is sufficient termination of the flashing material. The flashing material shall always be fully adhered to the curb substrate, even in loose-laid and mechanically attached systems.
The proper curb height should be a minimum of 8 inches above the completed roof surface to eliminate the potential of moisture entering the top of the curb area.
The flashing should be properly terminated - with a fastened termination bar or secured counter flashing - to eliminate the potential of flashing slump or slippage. This is particularly important on use of the heavier modified bitumen flashing sheets.
Flashings should always be additional material applications - separate from the membrane application - and should fully extend from the top of the curb out onto the roof surface a minimum of 4 inches. Application should be in accordance with the membrane manufacturer’s requirements.