Parapet walls are built on concrete flat roofs. The height of the walls is three to four feet high. They are built on the edge to secure the flat roof. This is done to protect people from falling off the concrete slab. The construction uses similar walling materials as in the building. This include bricks, concrete, glass, aluminum, masonry or steel. Steel balustrades may also be used as a parapet. The walls has a coping stone for weathering.
The parapet wall is erected using strong mortar. Since the walls are in the open roof, they must withstand wind or weather pressures. Depending on the type of concrete slab, solid wall materials should be used. The floor finish of the flat roof is protected by the parapet wall. Also the drainage channels within the roof are protected by this walls. After the erection of this short walls, water proofing of the flat roof is done.
The parapet wall position is marked around the whole flat roof. The thickness of the wall without finishes is minimum eight inches. A damp proof course of bitumen is first laid out. This is to prevent moisture penetrating into the ceiling below. The wall masonry is built normally as in other floors. During the concrete slab casting, stub columns are left to hold the parapet wall. The wall hoop iron reinforcement is joined with the columns.
After the parapet wall is ready, finishes on it can start. The coping stone is laid above it. This should be wider than the wall the including finishes. This should be at least ten inches wide. this will leave an overhang of one inch on each side. The external part or facade should be finished similar to the building decoration. The internal part is rendered. It is steel floated to weather of dust. After it is dry, external paint is used to finish off.