Monthly Archives: August 2010
In more ways than one, stone is among the most complete and eco-friendly construction materials
There are millions of buildings all over the world built completely with stone, right from foundation and walls to floors, stairs, columns, beams, roofs and parapets. But for re-sizing, constructed stone is the same as what nature has provided us, with no processing at all, unlike mud and wood which get partially altered by us.
Staying cool in summer and warmer in winter, it responds to local climate very meaningfully. After the life of the building, stone returns to earth equally easily.
India is a fortunate country, in having abundant supply of stone as a possible building material, both in variety and quantity. Eastern Maharashtra may be rich in basalt, Rajasthan is full of marble, while Kerala has extensive laterite deposits.
The pink sand stone of Jaipur region is synonymous with the pink city itself. Local inhabitants have discovered what the nature has in store for them and accordingly, each region has historically developed the art of building with stone.
Rocks and boulders
Bangalore region sits on the Deccan plateau, with both sheet rock and boulders. As such, granite size stones, boulders, slabs, hard aggregates and other variants are commonly available here.
Depletion of natural reserves is a major cause of concern today, with excess stone quarrying denuding the large rocky countryside. As such, while we may credit stone as a complete eco solution, it will have to be used judiciously in future.
There are better alternatives for columns, beams and roofs, where we can spare stone, leaving it mainly for foundations and walls. We often come across walls with both side stone left exposed with thickness up to 15 inches, while stone composite walls with 12” thickness are more popular. Much thinner walls at only 8” is possible with slabs, but they cost twice the regular ones due to cutting and dressing.
The criteria of cost resulted in many houses with random rubble walls, an 18” thick wall with irregular stones and no straight jointing. They appear very natural, however demand an experienced mason to build them and waterproof the joints.
What most of us see as stone wall, in recent times, could actually be normal brick wall finished with a large slab or small cut stone pieces, known as cladding. It ensures speed and even surface, can be applied for lintel or RCC edges to hide the concrete look and create different patterns.
Cost is a major concern here, also the aesthetics. Such walls often lack the real stone look, due to the slab face and tend to appear decorative.
Methods of building with stone could be different, but the basic precautions to be taken are similar. Learning about these principles itself can be an exciting journey into architecture!
Every other builder or designer claims that he can work with all materials, when actually, the facts are otherwise
Working with a material is not as easy as it appears. We need to know the characteristics, how best to use it, common problems and possible mistakes that we may commit. It’s like a chess champion knowing the opening game, a cook negotiating with a vegetable or a potter working with the type of clay.
The master works with ease, where the novice still struggles. Unfortunately, in the construction field, everyone poses as a master with every second builder or designer claiming they can work with all materials! In all of my 16 years of consultancy, I am yet to meet a contractor claiming inability to build with stone, even when they accept not having ever built a stone wall earlier.
This long introduction became necessary, in the light of occasional discussions the professionals have been having about disseminating information in public.
We still remember what happened to the image of soil cement blocks during its early years, when it was made and built without proper care.
Often, we see exposed brick walls so badly done, and I want to say, “Someone please plaster it off immediately!” This happens mainly when a helper is assigned to build a wall and a brick layer becomes a stone mason overnight.
All material technologies demand certain lead time to understand how to use them, before a builder can start with them.
Real picture: Architects, masons and others need some time to understand material technologies before starting the building work
As such, while writing about construction is useful, it may also lead to creating overconfidence among the practitioners, who may try their hand on field without adequate preparation.
Composite walls that we discussed last week face this danger more than any other wall type. Most masons get no chance of visiting a building under construction with the said technology, so end up re-discovering the wheel of learning all over again, making the same old mistakes in the process and killing the great new idea for ever. Unfortunately, while people have gained expertise during their practice, no major attempts have happened to record their knowledge as a code of practice or builders notes to help others learn.
Even if we have such texts, it can only compliment the hands-on work. Design, however cerebral it may be, finally ends up as a visible and tangible act.
Architects and owners observing a finished building during day light, builders learning about the experience of others and masons actually building sample walls under expert supervision are all among the mandatory preparations a project should undergo before embarking on the alternative path.
Working with a material is not as difficult as it may appear, if we can prepare well.
People working with clay crafts can tell us the finishing like glazing and pattern-making makes the pottery better, but costly as well. It is true in building construction too where the finishing costs are double of basic superstructure, hence our emphasis on leaving the material exposed.
In a composite wall, the outer and inner layers need to be tied to each other by a single stone going through the thickness of wall or a small piece of reinforcement rod or there should be adequate randomness in the wall core such that two layers do not fall apart. The course height would vary between stone and bricks, so only occasionally both would be at same level, which is acceptable.
However, when they reach lintel or roof bottom, both the materials need to reach together. It demands pre-checking the course height and the mortar joint thickness, adjusting it to match with levels as needed.
Periodic checking of levels with water tube levels is a simple measure to ensure quality of finish. To maintain uniform joint thickness, a piece of wood of desired thickness could be used as a standard reference.
If both sides are to be exposed, the electric conduit pipe should be laid within the wall during construction itself!
Composite walls in stone and bricks have all the potential we need, but one precaution: once done, there is no changing; hence the first time itself, we need to get it right.
Soil was processed to get building mud, dried under sun resulting in un-burnt mud blocks, fired up to get burnt bricks, then evolved into better types like chamber and wire-cut bricks. India exhibits, historically and otherwise, a wide range of brick structures.
In composite masonry walls, needless to say, bricks are among the most commonly used. The outside demands burnt clay blocks or wire cut bricks with high surface density and resistance to wear and tear, while the inside could be the normal table-molded bricks suited for plastered finish.
Granite stone, either as size stones or as slabs, is popular in composite walls along with bricks in Bangalore contexts, both being local materials. Just working with stone and bricks, often keeping stone outside for elevation and then reversing at other places, making it the internal wall, is actually fun! The resulting external and internal patterning can be so interesting; no additional efforts would be called for to create the building elevation.
Leaving material exposed
Why are we repeatedly emphasising on leaving the material exposed? It is not only to reduce heat gain, but equally well to reduce construction and maintenance costs.
People working with textiles can tell how cheap the basic cloth is and how finishing it demands money. Hence, using khadi or simple kora cloth is always an economical solution.
Let us at least feel happy that composite walls have been rediscovered and are gaining popularity
Attractive: Indoor and outdoor walls can have different textures
Everything in nature requires protective external cover, just like our own building walls. The difference is simple – nature has designed millions of plant and animal skins while we have only a handful of wall solutions.
Let us look at a dry coconut, complete with its inner shell and thick outer protective layer. The outer skin is so hard it requires sharp tools to peel it off. After we de-husk it, we see the inside being soft and fibrous, in total contrast to the outside finish and surface. Let us peel a banana, scrape a cucumber, study animal skins, or cut a pumpkin.
The story is the same, with the outside skin designed for harsh external environment for survival, while the internal surface is finished simpler, relating more to the soft pulpy contents inside. There is no logic that demands both to be same. Instead, the inside and outside being different is the logic.
Now let us look at our own building walls. Nearly all that we build today has a wall plastered and painted both sides, almost similar but for the type of paint. Incidentally, architecture from the past exhibited at least some variety. The grand palaces of Rajasthan, all built with stones outside, did not have stones visible inside. They were smooth finished, with stucco, niches, mirror, paintings or anything else that the room wanted. The rural houses in northern Karnataka have walls in stone, built with minimum masonry joints, but inside finished with mud plastering. Laterite walls left exposed are a common scene in the vernacular architecture of the west coast, which are rendered with lime mortar inside. Fort walls were constructed with stone on both sides.
Off with colonial ideas
With all this background, why have we forgotten the lessons from the past? We can cite many of them including the imposition of uniform ideas from the colonial powers. Leaving it all aside, today, we can feel happy that composite walls have been rediscovered and are gaining popularity.
It is building a wall with one type of material or finish outside and another type inside, both decided as per the needs of respective contexts.
Over the last 15 years, our firm has explored numerous combinations of singular or composite walls with soil cement blocks, granite size stone, normal table molded bricks with plastering, wire cut exposed bricks, hollow clay blocks, Besser cement blocks, hollow jail or perforated walls, stone slab walls, rat trap bond walls and such others.
Right decision needed
Each material and construction type needs to be judiciously finalised, based upon location, cost, heat gain, elevation aesthetics, maintenance and the desired final finish.