Careful consideration must be given flashing systems where a roof joins a wall. The base flashing system must keep water from entering the build ing and must be designed to provide for building movement. Counter flashing serves to turn water from a wall onto the roof or base flashing.

Metal counter flashing should be used in conjunction with composition base flashings. Composition base flashing should be applied accord ing to the roofing manufacturer's specification.

It is recommended that base flashings be applied over a cant and be extended up the wall a minimum of 8 in. above the roof line. Metal counter flashing is installed so that a minimum of 4 in. of the base flashing is covered. Metal base flashings are used with shingle or metal roofs. Metal base flashing is not recommended for use in lieu of composition base flashing with built-up roofing. A metal base flashing may be used over a composition flashing as a protective cover in loca tions where the base flashing may be abused by traffic.