Slabs come in many shades to protect your building from intense heat and rain. By Sathya Prakash Varanashi
Ask anyone if he or she prefers sunlight or shade – the answer is predictable with no failed guess! Shade is what all animals need, including humans.
Early architecture in the tropical zones of India had an overarching criteria in creating shade and it was more critical than any other criteria. Incidentally, it continues to be an important consideration even today in eco-friendly designs.
Creating shade for the whole wall is among the early knowledge people picked up while designing for climate. Initially achieved through simple ideas such as projected roofs, closely placed dense housing, deep verandahs, planting trees and such others, slowly led to windows set in thick walls, projected jharokhas and roof stone extensions. Traditionally, designs had deep roof eaves such that sun light and rain would not penetrate deep into verandahs, porches, porticos, entrance mukha mantapas, balconies and walls facing south and west.
Formal study of buildings by experts led to variety of options to shade specifically windows, leaving the wall open to sunlight. In normal buildings, it is common to see the horizontal chajjas or sunshades, done today mainly with RCC. Many windows also have vertical projections on both sides called fins, or it could be projections all around with a box chajja. RCC has emerged as the most prevalent material for all these, though it is not among the best options.
Among the less studied category are vertical drop slabs useful to stop both the sun and rain. They also protect our eyes from direct sunlight even when we are sitting outdoors in semi-open spaces such as balconies or entrances. Often, the upper floor common passages along the outer edges of commercial buildings would have them, so the lower floors will not get direct rains. Most city homes have car porches with a room on the first floor, so the clear height of the car porch may reach up to 13 feet. If the house faces south-west or direct west, evening sunlight would reach deep into the porch, heating up the car due to light and wetting it due to rains.
These vertical drops cannot be done with simple masonry, while complete concrete solutions could be costly. Traditional buildings could afford to have wooden planks in this area. Very often they are done with chicken mesh plastered on both sides, also called as ferro-cement slabs, but they tend to crack under strong sun over the years. Some designer buildings exhibit well placed horizontal louvers, which demand good detailing and execution.
Simple solution
A simple solution lies in using any stone slab, sheet metal, large clay tiles or matted material that can withstand direct sun and rain. They could be fixed with steel channel sections hung from roof slabs by inserting the slabs within the sides or grooves of the section.
If well designed and detailed to match the elevation of the building, the vertical drop slabs can be an element of attraction, rather being an ugly but unavoidable addition.
(The writer is an architect working for eco-friendly designs and can be contacted at [email protected])
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