Designs and the carbon trail

One area of construction where past practices have changed drastically is floor finish. 

Architecture is an expression of its time and the space where it gets built, as such subtle shifts in our design approach are both welcome and inevitable. Where technology impacts, quality improves or cost reduction is enabled, we notice greater degree of change. Till recently, such emerging ideas were never validated with energy consumption as a criterion, but now our urban lifestyle makes it imperative to check the carbon footprint of our every action. Though the apprehension about depleting world resources has been around for many decades now, consumption has not reduced, but only increased. Hence, the greater urgency to be critical about our choices.

One area where the practices of the past have changed drastically is floor finish. For the older generations, the floors where they played and grew up have virtually disappeared. On site, hand-finished floors are being replaced by manufactured tiles; local options are getting wiped out by outstation products and pre-finished floors are gaining an edge over site finishing. With the new materials being factory produced, it is judicious to evaluate them for their varied impacts.

The unfortunate part of the story is that flooring materials have never been a major part of the sustainability discourse. It is not a challenge for the structural engineers, while most architects leave this decision to the potential building users, leaving a major single item of work to the discretion of the builders and owners. Naturally, the market dominates, where profits matter the most, diluting all professional concerns. Shortage of skilled labour reduced red oxide finish, ready-made mosaic tiles eliminated on-site terrazzo, ceramic tile emerged as a single solution to all flooring needs and innovative materials like vitrified tiles are affecting the future of ceramic tiles.

The shift from hand-finished floor to factory-finished floor has also been a shift from a low carbon solution to a high embodied energy solution. The argument in favour of this shift cites the time and labour intensiveness of traditional methods like red oxide, problems associated with chips coming off in a mosaic tile, ceramic being prone to surface cracking, and so finally, vitrified tiles as the best in the line-up, being a product of extended research and development

Go for the right method

Where to use and how to build are the deciding factors for success stories in antique materials

In construction, each material dictates its own approach. While all that red oxide flooring asks for is skilled hands; in cement block work, the material quality matters the most; detailing is most important for skylights; and weather protection is an overriding criterion for building with mud. This introduction seemed necessary to respond to the enquiries for the last column on antique pillars, where the right kind of location and application is more important than just being able to procure antique materials. Where to use and how to build with, decide the success stories of old carved wood.

Antique pillars

While walls can be built up to any height, antique pillars are short, hence need them in advance to match their heights with the masonry constructions. Though they are mostly found with sloping roofs, they can also be used for flat roofs by adding a brick or stone base to increase the effective height.

Let us never expose these pillars to sun and rain in a new place that they are not accustomed to, for the pillars deteriorate fast. While re-using pillars, the ends developing cracks is a common problem to be carefully attended to. It is better to leave the broken carvings least attended to without much repairing, since the new wood stands out creating a visual mismatch.

Matching the antique with the modern and points of their junction are among the most critical areas of concern. Concrete and wood may need a steel plate in between; a plain stone base may lift the wooden pillar above the floor protecting the base; metal pastes may neatly conceal an awkward joint, also stopping water penetration; clamps and bolts may do a better job than nails; and uninstalling carved four-sided capitals may help if the pillar has to simply meet a flat roof.

Natural materials

In the past all wood applications were made from natural materials, unlike today where chemicals dominate. The former ones would not seal the surface, letting the material breathe and perform differently during varying seasons.

The modern paints, sealants and polishes make wood impervious, in the name of protection, but allow internal dry rot. Hence it is imperative to work with carpenters who use traditional methods, be it linseed oil or hand working to ensure the material lasts. They can also distinguish the type of wood and treat it accordingly.

Re-used carved wood

Building with re-used carved wood demands patience and sensitivity. Once built, they demand time and maintenance. If we intend to use antique materials, it will be good to have not only pillars, but also doors, shelves and such others. Needless to say, the doors have to be bought in advance to ensure perfect fit into the door opening. Without such an overall ambience, antique pillars may look out of place. Mix and match of antique elements with modern construction may appear bad, taking away all sense of history! Let there be the visible touch of tradition.

Seen the Madras terrace?

If you think Madras terrace roofs are forgotten, just visit Auroville to see a few of them standing high

If we pull out any textbook on flat roofing written during the last century, it’s possible that the most prominent chapter would be on Madras terrace roofing. Those were the days when flat roofs were becoming popular, where vernacular flat roof forms had one or the other problems. The Madras terrace method of construction, in many ways, incorporated the best of all known roof forms, avoiding their pitfalls. Thatch roofs were not fireproof, roofs with twigs and branches had termite problem, and mud floor roofs were thick and heavy.

Also, there was a desire to move from the kutchha or seemingly short life approach to pucca , long-term methods. The role played by the British engineers in the evolution of Madras terrace needs to be mentioned here.

Wooden beams, normally teak wood in those days, would be first placed upon opposite walls across the width of the room, 18 to 24 inches apart. In case room spans are wider, steel sections would be first placed dividing the room into shorter spans, along which teak beams run.

High density and high strength clay bricks, made to special thin size measuring 1”x3”x6”, are used in Madras terracing. Properly mixed and matured lime mortar is used for bonding the flat tiles that are placed at an angle of 45 degrees to the wall, or diagonally across the room width.

These terrace tiles, placed on the edge, ensured tensile strength.

The roof is cured for a minimum of one week to achieve early setting. Thereafter, a three-inch thick layer of broken bricks or brick bats would be laid where nearly half the volume would be made up of lime mortar, three parts brick, one part gravel and one part sand. This layer provided the compressive strength and load bearing capacity to the roof. This layer needs to be well compacted, cured and levelled. The final layer would depend upon the slab being an intermediate one or the final roof. If intermediate, a floor finish like red oxide or lime mortar would be applied and if final, there would be courses of flat weather-proof tiles topped by thick mortar to slope.

Rethink

In case we believe Madras terrace roofs have already been written off, we need to rethink. There have been attempts in a few cases, including at Auroville, to revive this technology.

We may not get the same old terrace tiles, but get thin perforated WPC tiles, cladding tiles and such others that can be used to build up the roof, supported by steel sections.

The roof would be thicker than our RCC slabs that should be considered in ensuring required floor heights.

Incidentally, the roof type was termed as Madras roof due to its widespread use in Tamil Nadu, though it became popular all over south India.

Even today, we occasionally meet people who can recollect having got their houses done with Madras roof.

The forgotten roofs

This system with wooden cross beams does not need centering, allows faster construction and demands less structural skills. 

Can the way generations before us lived for thousands of years be continued today? If some ideas are extinct today, where did they err? Do they have any future at all, or are they better forgotten? Before we go into this debate, let us look at some of the past practices, now less used and on the decline.

If we walk into any typical village, we routinely see houses where the roofs have closely placed wooden beams, often as close as six inches, which have wooden twigs and short branches above them, running in the opposite direction. There could be some dried leaves visible above them, or it could directly be a layer of mud mix. These houses were built with minimal cost, often termed as kutcha and face fire, rodents and such other problems. Alternatively the wooden cross beams could be topped with a piece of burnt flat clay tile. The tile layer gets a mud layer on top with the final floor finish.

Where ample quantity of construction timber is available, we see wooden cross beams at a wider span, say 1 to 2 ft. wide, which support a layer of min. 1.5 inch thick wood plank on top. In most houses, a thin layer of lime concrete could be seen above this, finally finished with red oxide floor. Mud flooring mix could also be used above the mud planks, in low termite prone areas. This wood beam concept comes with different variations, among the popular ones in many Sates being stone slabs replacing wood planks as the base of floor material. Any good local stone could be used for this purpose, though stone slabs have defect lines depending upon their material composition, hence are liable for cracking.

This system with wooden cross beams does not need centering, allows a faster construction and demands less of structural skills. These roofs are local by nature, hence more eco-friendly and sustainable. On the negative side, we may list the difficulties of electrification, and feasibility of base materials such as wood or cuddapah. However, this system could be revised by replacing wooden cross beams with steel joists and the sub-floor base by flat hollow clay hourdi blocks or granite or RCC slab precast at site.

When a construction idea popular for centuries loses out, mostly it happens for no mistake of the idea. People may make a mistake in implementing a construction element, but that does not mean the idea is wrong and needs to be discarded. However, if seemingly better ideas get introduced, the earlier systems become less desirable. Most traditional vernacular roofing ideas are still valid and in case newer, better ideas are not possible in the given site, can be replicated.

To that extent, it is advisable to do research on our past architecture and ready them for modern applications.

Climate crisis, and the culprits

Degeneration of the atmosphere is mainly because of modern mechanical devices which have become part of our daily living. 

As schoolchildren, we started reading alphabets not as mere graphical forms, but as the starting letter of a larger word. So A for Apple, B for Ball, C for Cat, D for Dog and so on it goes. Imagine, if we were to start the same again to check what impacts ecology the most, it could be a bad start.

A can be for Atmosphere, but soon we may follow it with A for Agriculture, Accommodation and Administration, all of which in the ancient times effected ecology where human actions altered the landscape to cultivate; consumed resources to construct; and created systems to govern society with capital and operational expenditures.

In modern times, A can stand for Advanced Lifestyle, but equally well for Automobile, Air travel and Air conditioners. Incidentally, these three are strongly advocated by modernity to become the aspirations of every low and middle-income family, who constitute approximately 75 to 80% of the Indian population.

These three are also among the major human actions adversely affecting nature and leading to the climate crisis. For common people, they may not appear to do so directly, but are the indirect causes due to their production, operation, energy consumption and finally waste generation upon discarding. Even the climate subject experts do not go to the depths of varied components of lifestyle, their attributes and implications on atmosphere, but gloss over them broadly saying human actions are causing the climate crisis. Then, of course, there are many people who do not fully agree with this position too.

Take automobiles, for example. Though the first car was patented in 1886, the next 20 years would not have seen more than 200 cars on the road. There was increased production, but between the World Wars, more car companies were closed than founded. The handful few from Europe, U.S. and Japan survived into the 1940s when the real mass production of cars flourished.

As such, it is less than 75 years now that people are driving cars and less than 50 years with the worldwide spread. Most poor regions have very few cars, while more than 90% of Indians still own no vehicle at all. Yet, the havoc the automobile industry has caused to millions of years of fragile nature is frightening. Hundreds of pages of data pour in today, yet none of which has reduced either car production or car sales.

Immeasurable damage

In the U.S. alone, 75% of carbon monoxide and 25% of greenhouse gas emissions are caused by cars, besides many other toxic gases including ground-level ozone. Nearly three-fourths of all of U.S. gas consumption goes for cars. The resources consumed and waste generated in their production, sales, operation and finally scrapping or dumping is virtually immeasurable.

Given this, how do we analyse the impacts of our everyday living? How do we take ownership of our actions to realise we are digging our own graves? Do we need more advanced research on global issues or simple search into our personal matters?

Truly green, and stylish too

Cob walls can take any shape, including curves, sculptural forms and furniture profiles.

Anyone who explored how our past generations built is bound to have discovered mud walls, be it of Didi Contractor up north at Dharamshala or Laurie Baker in deep-south Kerala. We owe much to such pioneers who re-created our confidence in eco-friendly approaches. However, the introduction of newer ideas has eroded societal belief in traditional systems, including the cob wall, which is among the greenest material with not even cement as an additive.

Soil mix with approximately 20% clay, 20% silt and rest sand, a proportion that can vary slightly, is ideal for cob. Chopped straw, rice husk or such non-decomposing fibrous binders are added to control cracking, and lime is added to make it termite proof. Once this smooth mix with no lumps is added with water, it shapes well as a ball or elongated egg. Testing it is important, checking for consistency by how it cracks while dropping, breaks while being pulled or feeling its stickiness to hand.

These handmade lumps are placed side by side, gaps filled with soil, pebbles, or burnt brick pieces. The surface can be leveled by hand and compacted by hammering. Each layer is checked for consistency in width, say 2’ or at least 1’ 6”, and allowed to dry before next layer is placed. The side of the wall needs to be smoothened before it dries too much using wooden leveling bar with the sharpened edge or even hacksaw blade.

Protection

Exposed cob is not advisable anywhere, especially the lower part of wall vulnerable to erosion by rain, where we may use stone. Since the soil mix is unstabilised, walls facing lashing rain would also need protection. Besides, the wall surface tends to crack, more initially and slowly later on through one full cycle of all seasons, i.e. up to a year.

Given these reasons, cob walls need crack filling with the same mix, later plastering with mud stabilised with cement and quarry dust. The final coat can be with lime or left as mud wash with oxides for colour effect.

To locate openings, we need to fix temporary shuttering, to be removed once the wall is shaped. Stone or wooden lintels suit the cob most, though thin precast RCC lintels can be inserted above very wide openings, to be finished with mud later. Electrical conduits can be fixed externally on the wall, though they can be embedded by making grooves like in normal construction.

Being a loamy material, cob walls can take any shape, including curves, sculptural forms, and furniture profiles. Feasibility of cob depends much upon space available for wall thickness, local climate, availability of the ideal soil mix, local precedence, the speed of construction expected and of course owner’s acceptance.

In India, we do not document our works adequately and provide knowledge to others. Given this, the documentation at Sacred Groves is really remarkable, besides which workshops by Thannal and website postings by many consulting architects today provide basic information if one desires to revive cob walls.

Your local material in construction

Reluctance to use bamboo is rooted in the absence of design standards and unpredictable performances.

Where do we source design ideas from? Today it is common to check the internet, books and may be a few buildings around us, generally creating buildings with a modern appearance.

Countering these trends, though occasionally, we get to see newly built traditional structures. They are contemporary, yet are traditional as a cultural expression. In many ways they perform better, functionally and climatically. The Nagaland style tourist facility under construction at Puri beach is a proof for both.

Naga bamboo is straighter than the local, besides being stronger thanks to its thicker outer shell and smaller central hole. It has nodes at shorter intervals with strong diaphragms. These average 5-inch diameter culms are being used for all structural purposes, while the rest of non-load bearing members are from Orissa itself.

Selection

Selection of bamboo is the most important, with every culm treated to reduce sap content. Lengths with signs of cracks are used for slicing and splitting, Split bamboo is commonly used as walling material, weaving it between the vertical bamboo frame to gain strength and reduce porosity.

Subsequently, mud mixed with hay or grass, stabilised soil cement mix or regular mortar can be applied on the surface. This kind of walling is also called as wattle and daub method.

The floor base has to take live and dead loads, so it is made of thin bamboos laid in close proximity with floor joist members, at 2 feet spacing. The final floor finish could be with mud grass mix topped with cow dung, wooden planks, cement oxides or even layer of local thin stones. The ceiling too may have the interwoven split bamboo appearance, but factory finished bamboo matts are now available as a ceiling finish.

Roofing

Roofing is among the more critical decisions in bamboo architecture. While the support system could be same as for floor, the final roof has to be appropriate.

Due to the possible unevenness of bamboo, direct placement of interlocking Mangalore tile is difficult.

So, thatch, metal sheets, ferro-cement and such others can be tried. It’s better to keep the roof angle steep, for both structural stability and faster rain runoff. In Puri, they are using local paddy straw which has shorter life, but it’s economical and easily replaceable.

Being wider at the base and thin at the top, round bamboo can be tricky in achieving uniform sizes and well secured joints. It is vulnerable to cracking and splitting, which of course, can be managed by experts. They would also know how to avoid getting harmed by split edges, sharp tips, peeling of skin and such others.

However, professional reluctance in using bamboo does not come from issues like the above. It is rooted in the absence of design standards and unpredictable performances, dependent upon species and location. But if we see how bamboo has lived with us for generations, it’s our duty to give it due regard.

The Bamboo Revival

It was ideal housing material for long but had lost favour in recent times. However, bamboo is slowly making its mark again. 

When an ecologically appropriate material finds less users, it is time to think. What makes the modern, energy guzzling material ride over the ecologically sensitive one? Equally well, if that material regains its popularity, it is also time to think. What brings about the green sense again?

Bamboo could be an apt example to this trend. Actually a grass, it consumes less primary energy than wood; assimilates more carbon dioxide for photosynthesis than trees, ensuring faster sequestering of carbon; reduces soil erosion due to its thick root formation; and produces more bio-mass per hectare than many other plants with its rapid growth.

An easy to transport material with surface tensile strength higher than steel, bamboo is best among the light weight construction options, where speed of execution is required. It sways with flexibility, hence does not break against fast wind; it is not a rigid construction, hence does not collapse during earthquakes; it grows very fast, hence becomes a rapidly renewable resource; and the culm can be used all through its thicker lower parts, thinner upper parts and the sliced surface.

Majority of construction techniques require externally erected scaffolding systems for holding the materials and workers, with larger buildings demanding cranes.

Building with bamboo needs all these minimally, with expert workers using the built part itself as the support. Even though construction happens part by part, once completed the building appears singular and interconnected.

Core strength

Yet, the execution does not lead to a monolithic construction, which is in favour today. The concrete, ferro-cement and modern organic forms appear monolithic in their final version.

Even the simple brick wall houses we do have a dozen RCC columns with walls plastered and painted to hide the individual masonry units, though they drain the money and strain nature. Bamboo architecture is neither monolithic nor hidden, which is actually its strength, not a weakness.

Bamboo has been best suited for thatch roof, country pan tiles, slates and stones, which can be comfortably fixed despite the slight unevenness of the canes. As roofing materials gave way for interlocking and overlapping tiles like Mangalore tile which demand perfect levels, bamboo lost favour. Coupled with the increasing popularity of RCC roof, bamboo slowly got relegated to the back benches.

In the past, housekeeping and maintenance was part of living in the house. Today people expect that the building be maintenance free, a pre-condition which rules out too many eco-friendly materials and construction types. Bamboo too is a victim to this trend, which cannot be cleaned all around, polished frequently or left exposed to sun and rain once built. As skilled labourers dwindled, popularity of bamboo also waned.

Promoting the cause

But slowly but steadily, bamboo is again in the reckoning. Internationally, books on bamboo are increasing and the one by Gernot Minke proves the value of the material so simply and directly. Vaibhav Kale, Sanjay Prakash, Neelam Manjunath, Uravu group, Sanjeev Karpe, Saajan and many more have been promoting it in their own ways. Bamboo has a future again.

If structures were biodegradable…

Whenever a building needs to be demolished, the debris should not pollute the earth. But the reality is different.

The human race appears to be very good in doling out data and statistics, including about impending disasters. If we wonder what we are doing with those doomsday forecasts, ironically, too often we do nothing about it. Among the best examples for this studied indifference is the research about the fate of modern products that we are recklessly manufacturing.

Try experimenting with banana peels in our household compost pit, where it will visually disappear in a week’s time, at fine particle level may rot the second week and finally at the molecular level, may completely decompose within the next fortnight. Slightly harder items like pumpkin skin or harder part of fruits may take a month to disappear and another month to decompose.

It will be curious to see how long a modern building would take to decompose and completely return to the earth. Of course, we do not have detailed research to answer this query, yet someday this may become an important issue in rating the sustainability of a design or construction approach.

Imagine a mall with elaborately designed shop interiors filled with Indian and foreign materials. We can appreciate them all as a great achievement of our generation and wish that such malls should thrive for generations serving our grandchildren.

What next?

Alternatively, we may also calculate the resources consumed, energy consumed, waste generated and the impact of the mall project on our times.

More seriously, we may wonder what will happen when the building and materials cease to serve any purpose and needs to be demolished.

Technically we can demolish everything; try recycling them to whatever quantity possible and the rest can be piled as debris somewhere on earth.

What will happen next? The materials need to decompose and return to nature. Is it easy for the un-natural products to return to nature?

If yes, how long will it take? For sure, we know that we cannot live that long to be on the day when a product of our time completely decomposes to join the earth. So, do we ignore the bio-degradability of what we are doing?

Respirometry test

Today, there are tests like respirometry, where solid waste is placed with micro-organisms and soil to check the quantity of carbon dioxide emitted due to digestive activity of the micro-organisms.

Though not exact, it gives fair idea of bio-degradation rate, so researchers predict that leather takes 50 years, aluminium can take 200 years, plastic beverage bottles take 450 years, plywood takes 3 years or glass bottle may take up to 1 million years.

The time taken also depends on specific material compositions and context of degradation.

Imagine a time when humans have gone extinct from the Universe. Will our mortal remains be the non-biodegradable manufactured materials? Can we be proud if the earth is full of leftovers of our times? Can our lasting contribution to nature be unnatural construction debris?

It is time to think of the footprints we are leaving behind.

NEW-AGE MUD HOUSE

The interlocking, electric machine-produced, stabilised mud block rises above many other new materials in its advantages.

Are our traditions dead practices? Is there no future for the ideas with which our forefathers lived? Should we believe that continuous innovation and constant change are the only paths towards a better future?

The above questions may lead to many debates, both favouring and countering, due to the mixed and confused state we are now in. While cultural studies may debunk the theories of innovation, technically loaded subjects like modern communication may like to drop the past. However, the construction industry may find itself at the crossroads, it being a synthesis of traditional culture and modern creativity.

Stabilised mud block, also called as soil cement block, is an apt illustration. It is a new technology developed from the age-old mud houses and well established in many areas, yet it has been criticised by many people for not belonging to the modern age of fast production, industrialisation, standardised qualities, ease of operation or skill-sets required. Now, the interlocking, electric machine-produced, stabilised mud block not only answers these critics, but rises above many other new materials in its advantages.

It has been few years since the pre-casting of soil cement blocks started in India, with technology imported from the African company Hydraform, hence has a proven track record. Unlike the manual pressed ones, they are compacted to the set density and strength in an electrically operated machine and cured thereafter. The blocks have grooves and projections on all surfaces, hence can fit one to another without any mortar joints. The interlocking arrangement which needs no pointing of joints is waterproof, besides easy to be fitted even by a semi-skilled mason. Alignments are, by default, guaranteed ensuring faster construction.

Sandy soil is preferred over high clay contents, and the mud needs to be mixed with tested and specified quantity of quarry dust and cement to give it additional strength, surface density and anti-corrosive characteristics. The blocks are pre-cured and construction has no mortar, hence no water curing is required, saving water and labour time. These walls can be load bearing with 9” walls or fill walls with 6” thick or thin walls with 4.5” thick ones.

More than 1,000 blocks can be made at site every working day with a single machine and team of workers. The machine can be fixed in one factory and can be transported where needed without much difficulty. In principle, these walls are made to be left exposed without plastering. However, pigmented blocks can be made or mud and lime mixed with oxides can be painted in case the natural block looks are not appreciated. With the block size of 9×9.5×4.5 inches, they are larger than normal stabilised mud blocks, hence have increased passive cooling capacities.

The house in Mysore by architects Dhyan Belliappa and Rajesh Jain is evolving in this right direction.

There are enough opportunities to make our past practices futuristic, only we need to be willing.