CURVING THE ROOF, differently

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Flat clay tiles make a hourdi roof easy to maintain, and the aesthetics are stunning.

What is the most critical part of a house – foundation, wall, roof, openings or staircase? The obvious answer is the roof, hence maybe the metaphorical meanings when we say ‘roof over the head’. It is of course, less visible than the walls, hence often gets lesser attention, especially where front elevation looks are more demanding.

While walls enclose the room providing protection, it is the roof that provides the true shelter. Unlike any other element of domestic architecture, here we face multiple issues to grapple with. Immediate thought could be about the structural issues, as to how to support the roof itself. Traditional architecture worked around local materials to solve this issue, while modernity has opened up innumerable options.

People across the societies have felt the need to innovate on roofs, either because there never has been a totally satisfactory design or roofs have had the scope to play with them. While the flat and sloping roofs have dominated at large, all other options have continuously knocked at the door.

Amazing forms

Contemporary architecture using advanced software to generate a profile, computer-controlled manufacturing of components and on-site technology to assemble them all have created some amazing roof forms across the world, with architects like Frank Gehry and late Zaha Hadid leading the pack of innovators. But do they mean in our small town contexts we need to be deprived of them? No.

The Learning Centre located at Salem proves the point. With the passion of promoter Sanjay and involvement of builder Arun, their team has managed to build a magical school building. It’s it not the just the roof which is special here, but the totality of design and building.

As such and with the concept of minimising cement and concrete, the design revolved around mud and clay.

Roofing with clay Mangalore tiles has been around for over the centuries, but it needs to be only sloping due to the interlocking grooves. By replacing them with flat clay tiles, one could create a curved profile. However, placement or direction of the clay tiles is important to ensure smooth curvature and to ensure that rainwater does not clog anywhere.

Typical computer formulae will not help in resolving the S-curved roof which adorns the school building, but only an experienced structural engineer like Ravindranath could resolve it. The structure also has domes, vaults, varied kinds of filler roofs, stone slab roof and such others. As such, the behavioural patterns of roofs need to be studied and equilibrium planned for.

Special attention

Of course, special attention is called for while assembling the roof for labour safety, joint filling and waterproofing the joints. The fabrication also has to be done to precision, lest the blocks may not be seated properly.

Curved clay flat hourdi roofs have advantages other than merely the novelty. They perform better for speedier construction, reduce steel with their lighter weight, ensure different aesthetics as against RCC ceilings and are easier for maintenance.

Be it the roof, wall or the whole building, architecture should not be driven by the idea of fancy, however attractive these new designs may appear to be. All the elements of design and components of construction should together aim to provide a holistic perception and experience.

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Single material, many uses

Mangalore tiles could be used to build walls, roofs, pavers and more.

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Majority of Indians were and still are used to having a space in the house where they could be eating at noon, children playing in the evening and cousins staying as guests sleeping there at night. The space we enter into on the first floor, often called a family hall, is even now considered for such varied roles.

Termed as ‘multi-functional spaces’ in architectural language, they have been among the basic principles of saving resources by minimising the need for multiple rooms for multiple requirements. While this has been commonly known and is continuing, what is forgotten is the idea of materials being multifunctional.

Buildings had to depend upon the few local resources for all construction needs, so people learnt how to use them with minor modifications. This also led to high theories like ‘single material approach’ much advocated by thinking architects such as Shankar Kanade and his brother Navanath. We may connect the visual powers of Taj Mahal, White House or Red Fort for their single material.

When Govindarajan, retired from IFFCO, desired to have a small farmhouse in his land, he could not but notice how people around the village built. He chanced to see a wall built with Mangalore tiles and wondered what’s the roof tile doing in the wall.

Discarded low-quality pieces and tiles from demolished houses not good for re-use get the common preferences here. Besides, one could see them on compound walls, edging a pathway in the garden, topping a parapet wall or even as pavers in broken condition. These tiles are very good at compression, hence we can load lots of weight on them!

Easy to build

A wall with Mangalore tiles is easy, cheap and fast to build with. With the rock hard tile transferring most of the load, the role of mortar joint is reduced to a levelling course. Cement mortar does not stick well to the surface, hence stabilised mud mortar is both appropriate and economical.

Routinely, these walls were inside and outside plastered. If built with stabilised mud and left exposed to sun and rain, they can perform very well on multiple fronts. They keep the house much cooler, thanks to an undulating and micro-shading surface which does not absorb much of solar heat. With a coat of lime, the walls come alive with a rare texture.

Local practices of today are being ignored in the face of regional or global ideas, but let us remember when these ideas were attempted in the past, they were not called as local practices.

They were the mainstream practices of the day, with no exposure to the global of the day. Apparently, these neglected and seemingly insignificant ideas were sustainable, while much of our celebrated newer and engineered construction ideas do not seem to provide a trouble-free stay for even two decades.

Without localisation and without realising the multifunctional potentials of each material and each technique, we cannot achieve a sustainable future.

Pristine architecture

We can actually live all our life in a forest, with food, fabric and shelter taken care of, avoiding the urban claptrap. Tamandua Rain Forest Research Station in Peru tells us how. 

24bgpTamanduastation1-RIOTjpgLet us imagine we were to be living deep inside a tropical primary rain forest. There is no real local vernacular style yet, so how do we proceed to design? We need to freshly create a local architecture from the materials offered by the context. That’s what we get to see at the Tamandua Rain Forest Research Station inside the Amazon forest, next to Las Pedras River in Peru.

It could be a large raised floor with wooden planks open all around to let light and air filter in from everywhere. The height of platform and railing would discourage crawling reptiles, rodents and such others from entering. Dealing with hot humid air is simplified by high roof with total void below roof, to allow hot air to move across the roof bottom, rather than let it move downwards from the roof. Room divisions are done with low partitions, just to provide visual privacy.

How to build

There is no electricity, telephone or internet connectivity. How do we build? We need to discover ways of constructing with human skills and basic tools that are traditionally available. The jungle is replete with construction timber for structural members, veins to get rope from them and tall grass ideal for weaving for roofing purposes.

Make the roof steep to ensure faster flow of rain water and greater structural stability.

Everything from the toilet gets soaked into the soil below. If we run out of cooking gas, firewood is around aplenty, which can also provide hot water for bathing, if needed. Food without the fancy looks and urban ingredients is essential and healthy.

Essential supplies to run the Tamandua Research Station need to come from a shanty settlement an hour away by boat. The typical daily wastes too have to be taken back, not to litter the pristine nature.

The station is not for recreation, but for research and exploring nature, as such it is austere and frugal. Yet, it connotes the possibility that we can actually live so all our life, with food, fabric and shelter taken care of. If so, why have we forgotten the pleasures of simple living and the simple pleasures of living, caught up on the trap of unsustainable lifestyle?

Until a few years ago, there was no supplied electricity, but now there are a few solar photovoltaic panels that give a little quantity of power before it gets totally dark, when one relies on candles. Until a few years ago, there was no Trans Amazonian Highway connectivity, so travel took day and night across boats, road and walking.

It appears, as we move into the present and the future, we miss out on experiencing the past. Soon, we forget it and so too about designing with nature.

The architecture at Tamandua station is the real sustainable architecture. It is born out of Mother Earth and when it reaches its end, it will return to Mother Earth. If we can keep the jungle, the jungle will keep us. Architecture without carbon footprint.

ROOFING WITH VOIDS

The mundane mud pot placed strategically by a skilled mason can cool your house.

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If people advise us to build only the way our forefathers built, to completely return to the vernacular ways and shun modernity, better not trust them fully. Returning to the past is, of course, a way of building eco-sensitively, but many not be either the sole way or the best way.

This is not to disapprove the benefits that we can learn from the past, but to forewarn ourselves about the possible traps in simply glorifying the past. Roofing practices provide good demonstrations for this theory. It’s well known how advanced were our seniors in providing long-lasting water-proof roofs with passive cooling and minimal annual maintenance. Comparatively, today we often complain about cracking and leaking concrete roofs which turn our houses into ovens in summer.

A thick layer of mud was among the simplest of solutions; it’s effective but not practical today in urban contexts, however much we may like to return to those age-old practices.

However, we may try to have a thick layer, but reduce the mass and weight by having voids inside. Roof heat transfers through conduction in solid materials and convection in empty space. Convective transfer of heat is very slow and much lesser than through solid mass. So, any hollowness embedded within the roof thickness reduces heat transfer, keeping the indoors slightly cooler.

Common practice

In many regions of northern India, it was a common practice to place small mud pots, either tea cups or 6 to 7 inch diameter clay trays, 3 to 4 inch deep on the terrace, with the bottom up. So, there is a cavity now above the roof top.

This layer of pots is filled to level using screed, either plain cement concrete 1:2:4 if water-proof terrace is needed or one may use stabilised soil-cement mix. Some lime may be added to provide water-proof qualities. The final top surface may be finished with white heat reflective cool roof coat, for additional thermal comfort inside.

In a recent project in Vikarabad near Hyderabad, this technique was revisited. Of course the availability of the clay pots led to using lesser number of pots than what’s ideal, but as an experiment to check its feasibility today, it was a success. In this case, this layer was laid over tandoor stone roofing, reviving another vernacular practice. It’s sad that though clay pots have multiple uses and benefits, their production has reduced due to the onslaught of produced products.

The void should be completely inside the slab to trap the heat there itself. Of course, once the air in the cavity gets heated up, some heat transfer would happen due to convection, but that would be much lesser than otherwise with no void at all.

The best is to have a ventilated cavity roof, which cannot be achieved by this simple using of clay pots. Only for very hot regions we may try such more advanced modes of passive cooling.

Pots inside thick mud phuska roof is not a new idea, but among those which are being forgotten. Before they are fully lost, we need to check the possibility of their modern applications.

The great wall of India

Houses of the past had walls built with mud and exposed to sun and rain for many decades with no sign of damage or decay. 

20bgpKudaliIttigeManneVillagejpgWhat could be an effective solution towards eco, green and sustainable? If we select two – being local and being frugal – it may surprise most people. Haven’t we heard these words too often, which do not belong to our modern times anymore? It is too late to live local now in our hyper-urbanised contexts and frugal living is an unfortunate curse on the poor, to be eradicated at all costs.

Given such thoughts, can we relook at the local and frugal, not as a curse but as a studied choice? Something common that we see across India while travelling is housed with mud walls. How many of us observe them, without taking them for granted?

If we go searching for the local and frugal, every other region has much to offer, especially in natural materials like mud and stone. In an old house in the historic village of Manne near Bengaluru, one can still see the old walls built with a specific technique called “kudali ittige”. Typically owner-built houses, we can still meet the septuagenarian seniors who claim to have built the walls with their own hands.

Mud for construction was dug out from their own land, also to get irrigation ponds; so it’s a double benefit! After careful sieving to remove unwanted dry leaves, debris, hardened mud particles and such others, it is mixed with grass shreds and small stone pebbles. Depending upon the actual soil characteristic, they may add sand, silt or gravel, for mud with too much clay cannot be built with. After two to three days of preparing the mix with water and foot trampling, it is spread flat on the ground to about 3 to 4-inch thickness.

Different sizes

Just before it gets set and very dry, the mat-like spread is cut into blocks using an axe to the size required. Since no individual brick is made upfront, this method allows for making bricks with different sizes as may be required by the construction of external walls, pillars, niches, thin inner walls or so. Primarily it is a variation in doing sun-dried adobe bricks.

Using the same mud composition, slurry-like mud paste is made to be used as mortar.

The wall observed at the site has been partly exposed to sun and rain for many decades with no decaying. Mud consolidated has become like a stone!

The soil varies from place to place, some good for cultivation, construction, pottery or even for toys. Soil for tubers is not good for rice – amazing to see the worldwide local variation within the same global material, without which early human civilisations would not have evolved up to our generation.

If we are, to begin with soil and end with soil and if mud has sustained humans all these 200,000 years, it is not fair that we forget it.

When Nature warns building sector

Cyclone Fani devastated infrastructure because we ignored sustainable designing and healthy construction practices. 

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How many of us have consumed less food after seeing images of starving children? How many of us have used less water after seeing images of famine-stricken Karnataka villagers? Hardly any, or may be a minuscule few.

Given that, how many of us will live consuming less of Earth’s resources so there will be lesser greenhouse gas emissions, after reading about the cyclone in Odisha? Possibly a handful. The drought conditions in one State and cyclone with windy rain in another State – yesterday it was in Kerala, Coorg, Chennai or Odisha and tomorrow it could be in Bengaluru.

These are not freak accidental weather behaviours, but a manifestation of major climate changes emerging across the globe due to increased fossil fuel burning demanded by the millions of products that we are producing. Both the shop sales and e-commerce boast of lakhs of products to be brought, yet the human demand for more products is going unsatisfied. Are these connected to cyclone Fani? Yes. Bhubaneswar was ravaged in 1999, and remarkably recovered. But global warming has relentlessly increased, causing more cyclones worldwide, this time targeting the Odisha coast again. The fact that we lost very less lives is laudable, but how often can we keep preparing for cyclones? What about the livestock, green foliage, power lines, roadways and infrastructure lost forever?

Videos showing buses overturning, small structures coming apart, trees being uprooted prove that nature is more powerful than us. If we wish to claim control over her, please no way. The alarming matter is cyclones are becoming less predictable, as the recent issue of ‘Down to Earth’ reports about the catastrophe at length. It is a paradox that Bhubaneswar is hard hit, the city designed by Otto Koenigsberger who wrote the book ‘Manual of Tropical Housing for India’ – an early text book on climatology not only in India, but also in the world. Unfortunately, we cannot blame either of them.

What is the connection between sustainable designs and cyclones? Across the world, nature is unleashing revengeful punishments against humans in multiple forms and locations. Cyclone is not an event of today but an accumulated implication of our last few centuries of agriculture and urbanisation, hence a warning signal for the future.

Could we have designed and built such that our buildings will have less of manufactured materials, hence lower embodied energy, which means less carbon emissions with reduced greenhouse gases that do not lead to ozone layer depletion, hence cause less global warming?

Resilience to risks and adoption to climate change are the mantras today, instead of eliminating the risks and stopping the change. At this rate, it will be too late.

Can stakeholders of the construction industry – promoters, owners, builders, material manufacturers, designers, managers, marketers, offer such solutions that may minimise damage from possible future cyclones?

Build sensibly or perish

If we ignore valuable advice given by architects of yore and construct buildings against the laws of nature, we are doomed.

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Victor Olgyay is the name few hundreds would have heard of in India and few thousands in the whole world today. Nearly 60 years ago, he started working on his book ‘Design with Climate” which got published in 1963. If he could advise us how do design sensitively and comfortably so long ago, why do we continue to ignore his wisdom? Some of the research topics he wrote about were arrived at much before him too.

Many forewarning kinds of books appeared shortly thereafter. ‘Silent Spring’ by Rachel Carson published in 1969 was path-breaking research on how chemicals are negatively impacting nature, mainly focusing on those which were used in agriculture, pest control and related issues. The organic movement now spreading wide has made people aware of all these.

Another early text, ‘Man Climate and Architecture’ by Baruch Givoni, got published in 1969, making the 1960s a decade of awareness building. However, after 50 years, the use of construction chemicals both in numbers and quantity is growing at an alarming upward curve.

India should be proud of the fact that it is among the first in the world to have had its own book on designing eco-friendly architecture, albeit written by a German. ‘Manual of Tropical Housing’ by Koenigsberger and others was published in 1973, and for more than 45 years we have an early manual for reference.

We have our own manual on climatology, but how much of it do we follow except as a textbook in colleges? How many students who study it for examinations forget it soon after and design architecture against climate? Why and who influences our construction industry decisions?

‘Design with Climate’ by Victor refers not only to all the basics of climate in general but applies that knowledge to design and construction. It contains topics such as an adaptation of shelter to climate; effects of climate on man; solar controls; bioclimatic charts; regional characters; microclimatic effects; basic forms of houses; morphology of town structures; thermal effects of materials; designs for different climatic zones and such others. Even though the book focuses on the U.S., the theory is applicable universally.

As such, more commonly needed data on wind, airflow patterns, heat, solar glare, sky factors, Sun path diagrams, shading devices, light intensities, passive cooling methods, lessons from traditional architecture, implications of massing and such others are all there. It is amazing to see how Victor attempted to cover a wide variety of topics with actual calculations using the early instrumentation available, which is so close to the more realistic ones available today with all software.

In many ways, its subtitle, ‘Bioclimatic approach to regionalism’ was the original contribution of Olgyay. This thought process, directly or indirectly, later led to many terminologies such as Bio-mimicry, Biomorphism, Biophilia, critical regionalism, eco-friendly ideas, local architecture, sustainable designs, green buildings and so on, and we can read shades of bioclimatic approaches in many other related theories like New Urbanism or even in Zero Carbon Cities.

It is easy to say Victor was ahead of his times to thank him, but it is a pity that we pay no attention to his research and advice even now, continuing to design against climate. It is time to realise climate change has already gone beyond our control and merely trying to design with climate will not stop the juggernaut. We have hurt, angered and irritated climate so much that now she is retaliating by warming up and speeding up in the form of cyclones, hurricanes and tsunamis.

Listening to Victor Olgyay and many others could have saved the east coast of India, mainly Bhubaneshwar and Puri, from being devastated by cyclone ‘Fani’. Are we able to see the connection between designing with climate and cyclones like ‘Fani’? If we are not, we as the human race are doomed.

For a ‘mudcrete foundation’

The composition may vary between places, though the basic considerations may include cement as the binding material.

11bgp-MudcreteFoundation1jpgThe first material early humans discovered for their construction purposes must have been mud under their feet and strangely it continues to be valid even today.

To deepen this exciting thought, just imagine a case where we dig out mud and put it back as the foundation! Yes, it was proven as a simple and fast system in many villages of Karnataka for small houses.

Excavated mud is added with broken tiles, stones or pottery with jaggery, lime and water. The mix is well trampled for two days while keeping wet, so it gains the required strength to be placed back.

Despite being a time-tested method, mainstream-size stone approach replaced it, and now sadly, the concrete column foundation is side-lining even the stone one, though RCC is mostly unwanted, costing more and damaging nature even more.

Concrete is like hard rock, but is a human product with cement, sand and coarse aggregate. If cement content can be reduced, the mix can last longer, but the prescribed mix strength cannot be compromised with. This is where mudcrete can step in.

Safe area

One safe area to replace concrete by mudcrete is in the foundation where the soil is hard with good bearing capacity. With both wall sides, the trench will never give way.

A normal 1:4:8 concrete mix at the trench bottom may act as a levelling and anti-termite course. Subsequently, mudcrete may be placed in layers of 9 inch each, compacted to about 6 inch thickness. At maximum two courses a day, a 3-ft.-deep foundation can be raised in 3 days, very safely.

The composition

The composition of mudcrete may vary between places, though the basic considerations may include cement as the binding material; sand to reduce shrinking and cracking; lime to resist termite attacks; mud as the base inert material; and brick bats, aggregates from rubble, broken stone pebbles or construction waste as the coarse material.

Proportions also change based on specific characteristics of mud and size of brick bats.

If the mud has more than half as gravel, about one-fourth silt and minimal clay, around 10% , it suits the purpose. Likewise, brick bats could be 20 to 40 mm in size, more of it in the lower sizes.

Given this, cement, sand, mud and the coarse material can be around 1:2:7:10 for a stronger foundation, and can increase mud to 10 and brick bats up to 20, based on site studies. Of course, all this needs expert supervision and engineering calculations.

A major step towards reviving it happened recently near Bengaluru for the house of Timmaiah along with students of architecture from KSSA, hoping to train the next generation. Mudcrete concept is diluted today for varied reasons, mainly lack of applied knowledge among the younger generation, hence failures. The ideal soil composition and availability of coarse aggregates could also be the causes.

However, there is no real reason why this should not be revived, at least for small and safe applications. May be it’s a matter of mind and time.

Mudcrete, not concrete

Natural materials last for long, while produced ones have to perish someday.

04bgp-GreensensG205QF96I3jpgjpgThis is a fact – longevity of construction hinges around one simple phenomenon: Natural materials last for long, while produced products have to perish someday. Even cement and concrete which are ruling the building industry today are not as strong or durable as the construction industry is making us believe so.

Incidentally, the idea of mixing fine particles, coarse aggregates and binding materials together was originally discovered during the days of Roman Empire, nearly 2200 years ago. They used broken bricks or stones with volcanic ash or pozzolona mortar, adding slaked lime too.

The Pantheon dome spanning 142 feet and rising to the same height has no reinforcement; it’s just the Roman Concrete, still standing tall after 2000 years. Innumerable markets, large gateways with wide vaults and many structures all over their ruled area stand testimony for this wonderful material. The parts of Roman ports submerged in the sea are still there, undisturbed.

After the fall of the Roman Empire, the making and building with concrete got lost. What we call as concrete today could be theoretically same as the older version, but the materials we mix and their proportions are not the same. However, we use the same name, despite the paradox that our concrete may not even live up to 100 years and in no way it can last 2000 years!

With minimal research and testing in this possibly new material that has been termed as mudcrete or earthcrete, not many people have confidence in this combination. However, in areas where load transfer has to happen only by compression, i.e. foundation, walls and such others, mudcrete is an economical and simple option.

Cheaper alternative

In civil engineering applications, stabilised mud mix has been successfully tried as a cheaper alternative for rock fill under roads and also in land reclamation. There have been a few structures built at Auroville. Many rural areas continue to mix mud with local brick waste and pebbles for varied applications. Yet, very little information is available from co-professionals and even on the Internet.

The quality and composition of mud varies between places; as such it is important to check the gravel, silt and clay contents of the mud to ensure the prescribed proportion is maintained. Brick bats, stone pieces and many other such materials are better suited as the larger aggregates.

Principles followed in rammed earth walls are also partly used here, though heavy ramming may be disastrous. If we were to revive mudcrete, many more ideas about how to use it will emerge.

For a masonry pier foundation

Though laying the foundation is the first task at site, it should be the last decision to be taken.

27bgp-greensense1erodefoundationjpgThe most invisible, but critically important part of any building is the foundation. Incidentally, though it is the first task at site, it should be the last decision to be taken, after all the ideas about the superstructure of walls, voids, roofs and such others are finalised.

Traditionally, foundation meant only one option – dig into the ground, run a thicker and widening wall down under all along the wall. Even if the building were to have intermittent wooden pillars, arches or any other design feature, full-length wall foundation was mandatory. Possibly, the failure of earlier structures would have made people wiser, to evolve the load-bearing wall system.

The idea of isolated column foundations connected by beams at ground level was introduced when the RCC frame construction became popular, where we could save time and money by not digging into the earth all along the wall.

Locations with loose soil composition, water-logged sites, constructing along sloping grounds and such other contexts hugely benefited by the RCC column footings. The discovery of this frame construction system with plinth beam is gaining popularity even in rural areas today.

On the flip side, this system meant the total building be built with concrete columns and beams resulting in budget escalation, higher embodied energy consumption and the need for a technically better supervised project. On most occasions, for simple G+1 houses, RCC frame is simply unwanted, but adopted to hike project costs to financially benefit all in the team. RCC is also short lived, unsustainable and difficult to dispose upon demolition some day in the future.

Imagine a case where the conventional load-bearing wall foundation would have worked out costlier due to soil condition, which gets realised only after the earthwork excavation. Is there a way out to economise without compromising on the load bearing capacity of the foundation?

Curious solution

Structural engineer Ravindranath Bontadka came up with a curious solution for a house in Erode by merging the plinth beam concept with load-bearing wall.

Load points were located, masonry piers as if the house would have masonry columns was introduced and the top of these piers connected by plinth beam. Now, the house plinth is ready for its nominal one or two floor construction without any RCC columns, but has equivalent to column footings underneath built with conventional size stones.

Surplus mud dug out from foundation trench was used for making interlocking stabilised mud blocks, leading to a win-win situation. Of course, we need to seek expert advice before venturing into such hybrid concepts.

Eco-friendly and cost-effective architecture is not a one-stop solution to be applied all over the country, like the RCC frame and slab system. Everywhere we see the one and only type of building with columns and slabs cast, later covered with walls, be it on a hill slope or the seaside. It’s time to localise our actions.