How to bring in curved roofs
They have a novelty and feasibility, yet offer eco-benefits, and hence are worthy of greater exploration
Advantage: Minor variations in the profile of the roof curve are generally not visible
What has made the digital cameras so popular? Why do simple cosmetics and body moisturizers sell so well? These questions may elicit many layered answers, but we can realise that logical necessity has not been among the prime reason for their popularity. Cameras being easily available or cosmetics being generally desirable have also contributed to their sales.
Likewise, in architecture too, we cannot reason every popular idea to their ecological benefits or economical budget. Some elevation treatment happens at great cost and effort simply because the owner thinks it makes the building better. Architecture also being an individual expression, we cannot question that owner. But what we can do is to infuse a logical ecological idea with a desirability or novelty, so that the idea becomes popular.
The curve inspiration
Curved roofs are a case in point towards this blending of advantages and attractions. The excitement created by the catenary curved roofs built by Barcelona architect Antonio Gaudi has not yet subsided. The early years of Auroville architecture, where many buildings were designed with curved walls and unusual roof forms, continue to influence the architect community. Curved walls and roofs were only a fantasy till recently, but now a reality, as such are being constructed more than ever. However, many doubts continue about how to achieve a good quality curved roof.
Standard roof casting methods suit flat RCC roofs, while curved roofs pose different challenges, primarily in erecting the centering, which also may cost more. The basic centering could be done with steel plates placed in shifting angle closest to the curvature, and then finished to the desired curve with mud.
Alternatively, brick bats could be used to get the rough curve, to be finished on top with weak mortar of 1:12 mix. Plastering the bottom of roof, with perfect curvature is very difficult, since the mason has no tool to check the levels.
As such, curved roofs are better done with alternative ideas, natural materials and rustic touch which go well without plastering. Minor variations in the profile of the curve are a part of natural materials, and generally are not even visible. Filler slab technology already discussed in this column is among the better options to achieve both the curve and good looks.
Once the formwork is ready, we need to assemble the filler blocks of chosen material along the curve, where we can avoid the ceiling plastering.
The lower ends of the roof, which curve more sharply, pose more challenges for handling and demand adequate labour safety measures. We can also profile the curve such that casting it may not be a danger.
We all know that an eco-friendly idea cannot survive by itself, if it’s not an attractive and easily do-able idea as well, however great the concept may be. Curiously, curved roofs have a novelty and feasibility, yet offer eco-benefits, hence are worthy of greater exploration and application.