Monthly Archives: July 2010

Building with clay blocks

New ideas have their share of problems, yet are finding acceptance due to their inherent attractions

Use the right technique: Many like the rugged looks of external and internal surfaces which show varying shades.

When a reader questions what is written, and when this leads to the critical examination of our perceived knowledge, a healthy dialogue takes place and leads to a better understanding of the subject. The last essay on hollow clay blocks has led to such a situation, thanks to two readers, posing different types of queries. Anyhow, we need to elaborate on building with clay blocks and the construction practices associated with it.

Wisdom tells us all new ideas are received with scepticism, but once accepted, they come to stay. What we call as the alternative mode of building has been there for over two decades now, with innumerable examples of well-built and lived-in houses.

There are thousands of structures in urban centres such as Bangalore and Mysore, exhibiting deviations from the norm, a few of them with radical ideas. People who live and work there vouch for the feasibility of these new ideas. Unfortunately, the common citizen does not identify them, while most builders and designers do not spare time to learn about them. However, if a prospective building owner seeks alternative ideas from their project team, they can always get a building of their dream.

Building with clay blocks is similar to the one with cement blocks, in the laying of units. Since the wall is left exposed, the joint mortar should not be placed up to the edge, both to save the wall getting dirty because of fallen mortar and to create the groove joint to later finish by pointing.

Most masons keep a wood section to size the joint thickness to evenness. The number of courses should be calculated in advance, such that once built, lintel and roof levels match with the courses. If this precaution is not taken, often we are left with a small gap between the top of the wall and the bottom of the roof, that needs to be packed separately, looking like a mistake.

During construction, daily wiping of wall ensures it stays clean, minimising cleaning costs. The blocks have voids inside, which behave differently from clay lump areas, with reference to humidity and temperature. As such, the unfinished external surface shows varying shades. This could be liked by some people as a natural pattern, or one may prefer to paint it thin to get evenness. One common practice is to have a mortar band around the window and door openings, to get the edges clean.

New ideas

There could be problems with alternative ideas, but the conventional modes are also not totally free of problems. In recent years, European, minimalist, contemporary architectural styles have become popular.

These new ideas also have their share of problems, yet are finding acceptance due to their other inherent attractions.

Every system has problems, only their nature differs between different construction practices. The challenge is to solve them, not to reject them.

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Have style and convenience

For respite from solar heat, either build with thick clay walls or create a void within the wall. Still better, try to build with hollow clay blocks

We can walk long miles under the hot sun, but cannot sit inside four closed walls for long; we can hold a lump of mud under the sun, but not even touch a lump of cement exposed to heat; and now the simplest example – we can hold a double-layered steel mug with steaming coffee, but not even touch it if it is the normal single-sheet type.

One can figure out what is being conveyed. Presence of air discourages the convection of temperature, mud and related earth products insulate heat and the gap between two layers of steel in the coffee cup reduces the transmission of heat from inside to outside.

What are the lessons to be learnt? For a respite from solar heat, either build with thick clay walls or create a void within the wall. Still better, try with clay and hollowness together, i.e. build with what we call as hollow clay blocks.

In short supply

These blocks were not available in Bangalore till about 20 years ago and even now are in short supply. Calicut, Mangalore, Kundapur, Huliyar, Kunigal and Tumkur are among the prominent places of their production, with minor cost variations.

Popular block size for load-bearing walls comes in 6”x8”x16”, with size variations in length and width being available. Being nearly seven times the size of a normal wire cut brick, the unit cost is cheaper, mortar consumption is reduced, wall weight is lessened and mud consumption at the factory is cut down.

Orientation

Buildings gain most heat from the roof and then from walls, depending upon the direction they face.

We may orient the building such that the least of solar rays fall directly upon the walls, yet during the course of the day, some sunlight would fall directly on the wall. The resultant heat transfer to inside can be controlled by using hollow clay blocks, especially in south and west orientations.

These blocks have high density surface grain structure, and as such need no plastering to make them water proof. Being exposed, the house stands out in the residential block and becomes a landmark in a short period.

We not only save on plastering and painting costs during construction, but also save on life cycle costs since these walls need minimal maintenance.

Hollow clay walls define a different kind of aesthetic play, and many find it adorable. Let us understand more about building with them next week.

Harnessing the five elements

Floors, walls, columns, beams, roofs — these five components form the superstructure of a building. Eco-friendly materials can be used in all of them.

Choice is yours: Think differently while designing a house

There are five elements and multiple techniques, in various combinations, that can lead to an eco-friendly and cost-effective building. In a lighter vein, these ‘panchatantras’ are floors, walls, columns, beams and roofs.

Of course, windows, plastering or fittings also count, but are not listed separately since they get clubbed under these main headings. In a conventional building with moderate final finish, these five components are together termed as superstructure, accounting for one-third of the total cost.

Alternative ideas may not save much cost at this stage, but the superstructure offers varied options towards eco-friendly materials and earthy constructions.

During the finishing stage, by using judicious materials and techniques, we can also achieve cost reduction. However, the green sense emerges from the totality of the building, from foundations to the final finish.

Over the years, our firm has worked with walls built with plastered cement blocks, normal brick, exposed wire cut bricks, laterite, stabilised mud blocks, aerocon light-weight blocks, exposed besser blocks, hollow clay blocks, coursed size stones and random rubble stones.
Likewise, the construction methods also offer options. Rat trap bond, composite walls i.e., walls with different materials in its two sides, curved profiles, short walls not reaching up to roof, non-load bearing walls, jaali or perforated walls and such others have enabled us to experiment with and experience from a wide range of walls.

Imagine having a choice of more than 20 types of walls, created by varied permutations and combinations of materials and construction! Yet, unfortunately, most constructions limit themselves either to bricks or cement blocks. Choice by itself is not important, if we do not know how to apply them.

The challenge

Being appropriate in a given context is the challenge, where choice should lend itself towards an informed decision. The decision cannot be based purely on cost or climate, but on a rightful prioritisation of project requirements. To that end, it is important to be able to assess the applicability of the options.

During the wall construction, there are multiple ideas for lintels, openings, shelves, lofts, chajjas, niches and such others.

Over the coming weeks, let us examine the wall options individually, understanding their potentials.

We are not limited by options, but by their applications. To that end, it is important to be able to think out of the box.

Accordingly, there are more than a dozen homes designed by us in Bangalore today, including that of U.R. Ananthamurthy, which have an open well, saving the money payable to the water board and saving the water for the city.

Open wells do exist!

Some old houses still retain them, and some new ones have got them dug

What did residents of Bangalore depend upon for drinking water before the water board started its supply? If asked in an inter-school quiz, this would be the easiest question to answer. They depended upon open wells within or around their sites. Now, the next question is: why did open wells vanish from Bangalore? Well, hardly anyone has the total answer.

Rare sight: A well with a lid

Before we start construction, arranging for water is important. Most owners dislike paying commercial rates to the water board and blindly go for borewells, incurring great expenditure. A quick look at the past gives us a simpler, long-lasting, cheaper and healthier solution in open water wells.

Let me confess: I do not completely know why open wells have become a rarity today, though one can list a number of possible reasons. Comfort of piped water, increasing pollutants, additional pump for well, lack of government support, small site contexts, subdividing of plots, decreasing water table and many such reasons might have caused the end of the era of open wells.

Good solution

Open water wells are among the best of eco-solutions for sustainable living. They may have to be dug to 3 or 4 feet diameter with RCC rings around for safety, preferably before house construction, but can also be done after occupation if we have adequate site area. Most wells fetch water within 20 ft. depth, beyond which, it may not work out economically.

Laboratory tests to check the water quality is important. In case it is not good for drinking, well water can be used for all other uses. Drinking water reaches us at great efforts and costs, which we tend to ignore due to its heavily subsidised pricing. Even if we can pay extra, it is not judicious to use purified water for construction.

Many historic homes in Malleswaram or Basavanagudi still use them, like the century old house built by Puttanna on what is now called Puttanna Road. Often, these wells are within the walls of the house, as such are not visible from the road. We often suggest digging open wells and surprisingly, most owners are excited by the idea!

Say ‘No’ to borewells

Look at better options such as RWH and buying water

Waste of money: Cities could do without such scenes

It is cheaper not to get a borewell dug, than to have one. The borewell investment can actually earn money, if not spent on drilling the well. No client walking into our firm believes in this statement, until we present the facts.

The ecological disasters of too many borewells in Bangalore are already known, hence let us look at the cost implication first.

True cost

Borewells in Bangalore cost, complete for drilling, pipes, pumps and connections, anywhere around Rs. 1 lakh, depending upon the location, water depth and sub-soil rock condition.

Let us imagine we invest this money with medium returns, say around eight per cent per annum. We earn around Rs. 8,000 annually. Due to water scarcity, if we have to get a water tanker bringing in 6,000 litres in one trip every month, say 12 times a year, the cost of ordering tanker water is less than Rs. 4,000 annually, at an average cost of Rs. 300 per tanker. Our net saving is Rs. 5,000, with the investment of Rs. 1 lakh still intact!

Recently, a prospective client reported that his locality is rumoured to get only weekly supply of water. The household need for water is around 750 litres per day for a family of five, which we can average at 5,250 litres per week.

Even if a modest underground sump and overhead tank store 5,000 litres in one filling, the annual shortfall is 13,000 litres or equivalent of 22 tanker loads costing Rs. 6,600 only. We still save from the interest money and investment as well.

Many years ago, before this calculation dawned on me, even I would not have believed the mathematics. Since then, we have been able to convince scores of prospective house owners away from borewells.

If we add-on the rainwater harvest for household purposes, which we have preached for over eight years now, the borewell appears to be a sheer waste of money. Unless we are left with no other option, borewells are not a must.

During the 90s, few of our residential projects had the borewell dug even before the construction started. Due to various reasons like siltation, infrequent pumping out of water, proliferation of wells in the vicinity and such others, the wells today are no more usable.

Of course, the owners do not worry, for their water needs are anyway met with by other means!