Do not neglect the Parapet
Historic architecture made a clear distinction between the normal load-bearing wall up to the roof and the non-load bearing parapet wall upon the terrace. In village homes if it was the simple mud wall itself going upwards, in palaces it would be ornate, sometimes with royal graphic symbols in the centre. Public buildings exhibit varied brick and jaali patterns to highlight the topmost part of the building. Beside such attention to aesthetics, the costs and the volume of the wall are also considerable. A typical parapet wall is more than one-third in volume compared to the walls of a room, and as such can not be simply left to the choice of the mason.
Often we see parapet done with steel sections, complete with designs and welded junctions. Being a high embodied energy material, with paint susceptible to fade, steel is not an ideal material. Replacing it with masonry material makes green sense, besides avoiding the possibility of steel rods rusting because of penetrated dampness thorough welding gaps. If desired, a few rods without any weld can be used. The open-ended wall top should be sealed with mortar band to make it water proof. Long lengths of wall tend to crack due to temperature expansions, which can be avoided by placing two steel rods inside the top coping mortar, turning it into a RCC beam.
Everyone prefers good looks, but it is not worth wasting money on a costly wall all around, invisible from the roadside. As such, the front parapet can be designed to look good, while the rest can use ordinary half-brick walls with short pillar support at every 10 ft. The wall design will have to be adjusted for varied lengths as the parapet folds and turns along the terrace. Planter boxes with flowers and creepers add to the green elevation; hence should be considered seriously. After all, they only need daily watering. These planters can be made on the terrace itself, with double-layered mesh wall and drain pipe into the terrace.
Theoretically, a height of 2’ 6” is secure enough, but can be increased to 3 ft., but this height calculation should deduct for the thickness of roof water proofing. Even at this height, a child sitting on it is dangerous, so more than the height, it is the design that matters in making it child safe. The roof slab and parapet base has a critical junction, demanding proper water-proof finish. Also, embedding the supports of water tank, clothes line and roof pavilion with the parapet wall or its short pillars should be done simultaneously, not as a later addition.
In hot dry regions parapets support shading, terrace breeze and climatic lifestyle, while in heavy rainfall regions there may be no flat roof or parapet walls. The roles could be substantial or minimal, yet it is important to realise that parapet walls also have a role in cost and climate.