Flat, sloped or curved?
Despite the options available, most people cast a flat RCC roof, often with unnecessarily heavy design.
If we look at Leh, Ladakh, not even one building would appear with sloping roofs, but in total contrast, all the structures in the Thiruvanthapuram Fort area have only sloping roofs. The island of Santorini is full of small domes over every house, while the floating villages in South-East Asia have thatched, hipped roofs. After all, the wall is a simple surface standing upon the ground that could be erected anywhere, with pillars that could be just done by keeping a pole vertically straight. It is the making of the roof that throws up challenges, to ensure the gravity force of the earth does not gobble it down.
Every region has discovered an appropriate system, suited for the local geography, geology and climate. Humid and rainy areas would have slopes, while snowfall areas would have a steep slope. Clay tiles, thatch, slates and such materials are found on these roofs. Hot and dry regions with ample supply of mud, like Rajasthan, built flat roofs. If good mud is not available, people tried out stone slabs, reeds and alternatives to gain flat surface.
Curved roofs are often mistaken as a new concept, they are actually very old. The Treasury of Atreus at Mycenae, Greece, has a corbelled dome roof built at least 3,250 years ago and still standing tall! From the igloo homes of the polar regions to the Mediterranean islands, early architecture explored roofs other than flat surfaces. In India, temple gopuras showcase a unique capacity in building construction. Of course, all the ancient curved roofs were geometrical following the rules of mathematics, invariably built with masonry using burnt bricks or stone.
Modern technology enables us to build any type of roof anywhere! The spans have increased, curves have become flexible without rigid geometry, construction budgets have become permissive and many newer roof forms have been discovered.
The design variety has increased, but the design logic has suffered. While some are prohibitively costly, some others increase heat gain into the building. Fancy ideas and false roof looks have also found their place.
Despite this increased range of options available now for roof construction, most often we see people routinely casting a flat RCC roof, often with unnecessarily heavy design. If we combine creativity with design logic without compromising on cost or climate, more appropriate roof architecture would evolve.