Final answer:
The max horizontal width of flashing membranes varies with type and application, generally ranging from 6 to 18 inches, guided by manufacturer specifications and building codes.
Step-by-step explanation:
The maximum horizontal width of flashing membranes typically depends on the type of membrane being used and the application it's intended for. However, there are general guidelines set by manufacturers and industry standards. For example, roof flashing membranes can range anywhere from 6 to 18 inches wide, while flashing for windows or doors might be narrower. It's essential to follow the manufacturer's specifications or consult with a structural engineer to ensure compliance with local building codes and to guarantee optimal performance of the flashing for its intended purpose, which is typically to prevent water penetration into a building.