Blog Archives

Building on old ideas with new methods

If the validity of architectural ideas has not changed, we should not discontinue them, but do them in a new way.

27bgp-lead_PP_G_G3_2988120gThere is a common behavioural pattern among all of us: we get excited by anything new. It could be cooking a new recipe or buying a new gadget; travelling to a new place or seeing a new film.

The idea of new has been among the greatest attractions for us, especially in these modern times, when every other thing around us is changing.

It is difficult to prove that this idea of new is innate to all biological beings, considering how all other animals live by. Their needs do not change nor do they seek the new. If so, where does our appetite for the novelty originate? Could it be due to cultural practices, commercialised attitudes or market economy? This larger sociological question becomes important to understand how to place an alternative architectural idea.

Accordingly, new products are being manufactured at a maddening pace, to satisfy our desires. Design ideas are not an exception either, where everyone tries to do what others have not done, as if we need to outwit the fellow humans. If everything about a thing is new – idea, purpose, material, making and technology – we appear to rejoice, but soon realise how short lived it is. So the race goes on.

New materials

One way to see newer thoughts take shape is by doing things that our elders did, but using new materials or technology.

Doing a dome is an apt example where the famed Egyptian architect Hassan Fathy rediscovered and popularised a new way of constructing a masonry dome, based on traditional ideas and methods.

Normally, dome construction demands much work in centering and formwork, as such does not become viable.

In this technology, there is no formwork support which gets replaced by a pivot rod to guide the location of each course work.

Each brick course is laid normal to the pivot which represents the radius of the hemispherical, so all courses are aligned to the centre point of the dome.

Novel idea

In the lower courses, bricks stay put firmly, but as we go up to the higher courses, there is the danger of them falling inwards. Hence brick counter-weights tied to a thread are wrapped around the top course to hold them in position till they get set. Ideally, only one course is laid everyday with cement or preferably mud mortar, with appropriate composition. The topmost opening can be left as a skylight or be filled with bricks closely packed to provide the arch action for load transfer.

The point here is not that we all should build domes, but that we can re-do what has been done in the past in newer ways.

Hundreds of eco-friendly and green ideas already proven have been discarded on the pretext of changed times.

If the validity of these proven ideas has not changed, we should not discontinue them, but do them in a new way.

EFFICIENCY OF DOMES

They can be built on any space without steel reinforcement and centering, with substantial savings in cost and time.

06bgp-green_GFL_06_2234609gThousands of monuments from historic times are still around us, fully or partly standing in good condition. What are the common roof forms of these extant structures? Very curiously, majority of them do not have the flat roof popularly seen today, but have curved roofs in the form of vaults and domes. If they were built everywhere and continue to be stable even today, there has to be reasons for their efficiency. And, they deserve our attention to re-discover this age-old knowledge system.

Dome is the commonly seen round roof form, often seen rising above the wall line. Mostly seen in religious and pubic buildings, domes have always been considered to be among the more elegant and dominant forms in urban skylines. Incidentally, as per Dr. Yogananda, who has extensive study and design of domes behind him, they can be built on any space without steel reinforcement and centering, with substantial savings in cost and time. Lack of skill and the apprehension it generates is among the reasons for not building with domes, so his team regularly conducts workshops, besides actually building domes to prove the point.

The process

If round rings of reducing diameter are kept one above the other, the resulting raised form becomes a dome. To build one without centering, the dome profile has to be segmental and not hemispherical for structural reasons.

First, we need a reference distance to get them all in place, so the dome dimensions are finalised and the centre point on the ground is marked. A long pole on a rotatable pivot is fixed here as a guide, the tip of which becomes the spot for placing the individual bricks. The dome compulsorily needs a ring beam at the base, and if not, needs buttressing on edges to carry the dome load away.

A rich composite mortar with soil, cement and stone dust or any other locally appropriate mix is used to fix the bricks, first in round courses and then one above the other, with the mason standing on the dome itself. Same bricks are tied with thread, and hung across the just placed bricks as counter-weights which prevent the brick from falling until it gets set in place. As the dome nears the top, another ring beam can be placed with skylight or solid surface finishing the top. Unlike the popular belief, domes need not be the last roof, but can be intermediate slabs with such shallow rise that the upper surface can be levelled to get another floor above. Domes tend to echo, though this problem can be solved.

The method of building domes without formwork support is actually simple, though it may appear complex. As such, it is advisable that masons take some training and the building owners consult an expert engineer.

Despite such limitations, masonry domes have been and can be among the most eco-friendly and cost effective solutions for roofing a building.

Domes: stylish, inexpensive

When time-tested ideas get fogged, revalidating them demands fresh efforts. Take domed roofs for instance.

A simple question: besides the flat and sloped roofs, what roof types do we commonly see in historic buildings? The answer from a majority of us would be: domes. Until about 100 years ago when steel entered the construction industry followed by RCC applications, domes and vaults (long roofs semi-circular in shape) were among the most common approaches for large buildings all over the world. Even today, in areas where only mud is available as the local material, the smallest of houses also has domed roofs.

If masonry roof structures ruled the world for thousands of years, they cannot be invalid now just because RCC is in vogue today. When time-tested ideas get fogged, re-validating them demands fresh and new efforts. This is what Hassan Fathy, an Egyptian architect did, about 70 years ago, in re-discovering the Nubian methods of making brick domes and vaults. While designers had written off masonry domes as an obsolete idea, Fathy sought masons who knew about the dying art of building them and went ahead with the projects. In India, Auroville and ASTRA group at IISc. played a pivotal role in making them once again popular.

Built in short time

Natural semi-circular domes can be built in a short time without formwork using Nubian methods. The centre pint of the dome is marked on the ground where a pipe is pivoted, which could be rotated to ensure the designed distance and radius of each course. Bricks are applied with stabilised mud mortar and placed along the radius. Since they are guided by the pivoted radius rod, as the courses rise, dome shape automatically evolves. Being a curved surface, one face will have wider joints, which can be tightly wedged. The mortar should be paste-like with high water content, such that each brick gets stuck to the other. Thinner the bricks the better, because lesser the masonry block weight, lesser the downward thrust.

RCC domes are equally well possible, but will cost more and have greater construction complications; hence the alternative modes of dome construction could be considered. Corbelling is another option to get either the vault or the dome. Here every subsequent course of brick projects out of the previous by few inches, resulting in a circular form, finally to close in on the top. The oldest surviving corbelled dome found in Greece is now over 3,500 years old!

In recent times, masonry domes have resurfaced with hundreds of buildings already built around us. They work out cheaper, appear unique and above all highlight the feasibility of the alternative ideas. Of course, domes have never been a regular part of our traditional residential architecture, though many masonry domes and vaults are found in traditional public buildings designed for a cultural image or for large gatherings. Anyway, in many parts of India, local masonry materials still being available and skilled labour possible, masonry constructions continue as a viable option.