Practice makes perfect
It goes unnoticed that a large number of people actually love arches and may like to see them in their homes and offices, but end up without one. The blame may lie upon the architects and engineers who hesitate to build them for fear of defects and mistakes. The mistakes could be blamed upon the masons, who had no chance to learn about arches with no proper instruction, ending up spoiling it all. While the trend of senior masons teaching the juniors has diluted, there are not many centres like Auroville, where one gets exposed to constructing arches.
However by studied observation, basic knowledge of arch action and sincere willingness, anyone can learn to build a simple arch, which can then be perfected across time. The critical point about an arch is not in the final product, but in the design process and in the making of the arch. Firstly, one needs to finalise the shape, be it semi-circular or segmental, depending upon the clear width, the rise and the strength of the side supports possible. This shape should fit well within the springing point at the bottom and key stone at the top.
The arch profile should be marked on the ground on actual scale using a thread as a compass, from the centre point of the arch, and double checked for accuracy. The central line should be drawn and the key stone marked, such that rest of blocks can be fitted equally on the either sides of the key stone. With the same thread, each stone or brick should also be marked, keeping the size of the said masonry block in mind. Now, each individual block should come in a tapering shape, all blocks should be in full size and the first block near the springing point clearly sized.
Now a dummy arch with open joints can be placed on the ground for final verification. This done, each block can be lifted piece by piece, building the arch on the wall, upon the temporary centering support provided. Unskilled masons also use a template of the curve, made from plywood, holding it across the arch under construction to ensure the profile is maintained. Over the time, skilled masons may do arches without such elaborate preparatory procedure.
Though all arches are curved, the specific type of arch may vary – with one or more layers, bricks projecting out, different placement patterns, mix of materials, pointed arches, twisted profiles, arches overlapping on each other and such others.
Providing just one arch in a building may appear out of place, hence using arches as a repetitive design element may be more pleasing, but it is important that the owners should appreciate arch as an idea, before trying them out. A flat RCC lintel comes with no choice, but arches come with dozens of variations, often at lower prices and different aesthetics. It is time arches get revived, before the skill levels vanish completely.