Monthly Archives: January 2019

A rammed wall with coloured earth

Faster construction, perks of low maintenance and aesthetics are the positives.

19bgp-greenppgnIs building with mud an outdated technology? Is it no more practical to do so, considering that a large number of manufactured and marketed materials have flooded our times, claiming better performance and perfection, besides variety?

This is a myth of sorts, which can be felt if we study the properties of mud, its durability and the range of aesthetic expression mud architecture achieves between different regions. With cob, adobe, soil cement block, interlocking mud blocks, rammed earth walls, pigmented walls and such others, the soil of the same place too can have multiple appearances.

Strangely, there are people who believe that natural materials like mud will have a supply problem, while factory produces like cement can be supplied forever. All manufactured materials require raw materials from some sources, mostly taken from nature itself, so they too have their limitations.

Architects, engineers and builders have built a wide range of elements using mud. To list a few, rammed earth foundation, stabilised soil cement block walls, different kinds of arches, corbelled projections, walls with inter locking mud blocks, vaults without shuttering, flat arch lintels, patterned and differently moulded blocks for parapets or compound walls, perforated walls in jaali, masonry domes without shuttering, mud block filler slab roofs, load-bearing pillars, rammed earth floor finishes, solid cob benches and fixed furniture, facia finishes, surface washes and such others have already proven themselves as doable and durable.

Should we believe that continuous innovation and constant change are the only paths towards a better future? Not really, with the carbon footprint of construction industry ever increasing. Fortunately many people today talk about the need to revive the past wisdom and blend it with modern times. But how many are willing to change the course towards natural materials is the million dollar question, especially if there are business risks associated with real estate and construction investments.

One mode of achieving it can be by value addition to the traditional mud construction. Patterned rammed earth walls have proven to be a pointer here, with increasing popularity. The mud composition needs to be the same as for other mud walls with around 15% of clay and silt each, the rest being sandy soil, but mud of different colours needs to be procured to achieve the layering of the earth. Such ideas not only let the skill-sets of the mason continue but also make them feel proud of their accomplishments.

The challenge is facing each one of us. The ecological advantages of minimising on cement, the financial advantages of faster construction, the life cycle advantages of low maintenance and the visual advantages of aesthetics of earthy construction need to be reached out to the masses.

In promoting mud architecture, each one associated with the construction sector, from the mason to the media, can play a role.

Building walls with earth

With scientifically improvised technology, mud buildings can be made to last for centuries, contrary to common belief.

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It is a curious phenomenon – we all live in a planet called Earth, walk upon it, build shelters with it, and eat from it, yet we are on our way to destroy it As such, re-connecting with the Earth appears to be among the major solutions to the climate crisis. Given this, in the construction sector, we need to return to Earth, in all its terms and versions like soil, mud, terracotta, clay, silt, gravel, sand or stone.

Let us ask ourselves a simple multiple-choice question. Among all existing structures in the world, what could be the most commonly found wall material? Choice of answers – stone, mud, burnt bricks, wood. Anyone with common sense may answer it as ‘it could be mud’. Besides being the most common and most historic, mud walls have much to tell about how we lived in the past, for they sheltered the history of human civilisations. Incidentally, mud walls have a future too, in these days of climate change and ecological challenges.

The construction industry today is being blamed for one-third of GHG (Green House Gas) emissions, hence is at a crossroads. To mitigate this crisis, there is an urgent need to minimise manufactured materials and promote natural materials. The least we can do is to attempt a synthesis of traditional construction systems and modern creativity.

This is where mud architecture comes in handy. The methods of improvising traditional systems have re-validated the use of mud, to claim a pole position towards sustainable architecture.

No modern material replacing mud is yet to equal all the qualities of mud walls. It has the lowest cost in most regions; lowest embodied energy; highest insulation from heat gain; option of using mud plastering; a possibility of coating wide range of natural colours; option for bamboo or steel reinforcement; and can be used for all parts of the buildings right from foundation to roof. With scientifically improvised technology today, mud buildings can be made to last for centuries. Unfortunately, too many myths have been spread about mud, including it cracks, taking time to build, difficult to repair, monotonous and such others, as if modern construction methods are devoid of all these. This myth has come to stay, despite the fact that the way traditional mud houses lasted for centuries modern ones may not, which everyone is aware of.

So, the hesitation to build an earthy building appears to come more from fear and apprehension, than from knowledge and experience. Fortunately, mud walls are making a big return in modern architecture, though it is limited to certain regions only.

The technology of rammed earth walls has now been researched into fairly deeply and proven by various institutions such as Mrinmayee, Auroville Earth Institute, and Hunnarshala Foundation, besides many individual consultants. It is time to consider building walls with earth seriously, to save ourselves.

For passive cooling of your home

The design behind the ventilated cavity filler roof.

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Global warming is happening much earlier than ever predicted, at which rate we may leave nothing for our future generations. While it is mandatory on all of us to reduce our consumptions, wastages, trash generation and such other measures, it is equally important to devise ways of comfortable living without depending upon energy and electricity.

Cavity roofs have been a partial solution towards passive cooling, with embedding clay pots, hollow filler tiles and such others. However, during extreme summers even the hollow clay tiles are becoming less effective.

Heat gets transferred through conduction and convection, the former through solid materials and the latter through voids and spaces. When the building terrace receives direct sun rays, it gets heated up and starts to pass the heat downwards into the room below. Even the voids inside the hollow clay filler roof would let the heat go through it, for this trapped air also gets heated with the surface heat being very high. In other words, the present day hollow clay filler roofs will let heat transfer through both the processes of conduction and convection, the void being a sealed one.

In case the trapped air inside the void which gets heated up is not sealed but move across to let cool air in, then the heat transfer would somewhat reduce. This can be achieved by inserting a small length of electrical conduit pipe between the voids of the hollow clay filler blocks, which are embedded within the RCC roof.

Once all the blocks are in place, a small length of pipes are inserted such that their ends are within the void of the filler block. It is not a continuous end-to-end pipe, which serves no purpose at all, but short connections between the voids. As the air inside the void gets heated up, it moves along the pipes to equalise the heat all over the filler block. At the edge block, this hotter air moves out of the block itself, while cooler air enters the voids from the other end.

Between the two outside edges of the slab, one would have breeze called windward direction and the other end will not have much air movement, called leeward direction. Air moves from windward to leeward directions, in the process pushing out the hot air accumulated inside all the voids of the filler roof. This would reduce the heat gain inside the room.

The ends are finished with a slight bend to block rainwater. Pipe pieces should not move so much that their end is within the tile gap which gets filled by concrete, in which case the continuous air movement will get blocked. All that the builder contractor has to oblige is let a few helpers insert the pipes, which is fairly fast. It’s a one-time investment of time and effort, to achieve passive cooling of a slightly higher order.