Monthly Archives: May 2010
Flattening an uneven site does not appear logical either ecologically or economically
One aspect where all of us — owners, builders and designers — need to be blamed is for the habit of destroying nature by constructing on undulating locations. Traditionally our country believed that sites should be in an unaffected level, strange in a nation of gently sloping regions, rolling plains and low hilly terrains. So, what we do is to cut the ridges, fill the valleys and level the uneven.
Even in the historic homes of the west coast where we notice raising verandahs in 2 or 3 levels, the ground had to be flat. The back filling of soil into the plinth must have been humongous, demanding large labour and cost. The ground water flow, disturbed, must have eroded soil elsewhere causing unwanted headache. The levelling cost added with foundation in greater depths must have hiked the budget. The possibility of creating a building elevation, growing taller and majestic, must have got lost.
Building in different levels
Have we learnt our lessons? Not really. We can build up the foundation in steps, corresponding to the site gradation, instead of it going down to the same depth everywhere. Better still, we can plan the building itself in different levels. By skilful planning and careful alignment of the structure to the natural site levels called contour, we can not only avoid unwanted cut and fill, but also keep the foundation depth to the minimum.
Designing with parallel load-bearing walls could be considered, where the cross walls need only a nominal support. In traditional homes with wood joist roofs, it was common to have a full-fledged foundation only for those walls which take the joists. Today, in RCC design, we can replace this system by one-way slab design. If these walls taking the slab load are running parallel to the contours, required digging can be further reduced.
In coastal Karnataka, the practice of proper foundation for the external walls with nominal ones inside the plinth is still prevalent.
In case of varying slopes within a larger site, providing plinth beam could be another simple system, where deep foundation trench can be avoided where soil is loose and uneven. Also, the engineer may advise us to execute a soiling course, primarily a large stone base to strengthen the soil condition. Of course, it is advisable to get the expert opinions and construction cost compared before jumping to a conclusion.
Anyhow, flattening the site does not appear logical either ecologically or economically.
This method saves on materials and cost but needs an innovative structural engineer
Strong and sustainable: The curve profile of the arch foundation being
The fourth in the series, ‘Green Sense’ is trying to inculcate sustainable methods in construction and suggest traditional wisdom and ideas to help people achieve socially responsible triumphs during construction.
Take the case of foundations, there are quite a few vital points that could be adopted from long-established principles…
Did you ever realise that building foundations have contributed to much of our historic knowledge? Surprising, but it is true across the world including Harappa and Mohenjodaro. They live long, being firmly held within the earth. It is the soil beneath which fails leading to the collapse of a building, and not the foundation independently.
Look at the Golconda Fort, with high stone walls perching precariously on the corner of a boulder with no separate foundation dug out by blasting the stones. With load-bearing wall systems, Golconda was possible. But the modern RCC column system demands that we blast the rock and anchor the footings. The financial and ecological implications are heavy. Actually, what we call as foundation is not the layer absorbing the weight. All the dead weight goes into the earth, and understanding the earth condition saves money and time.
A good engineer can design an efficient foundation by mere site observation. If in doubt, soil test should be done and in complicated cases geo-investigations may have to be undertaken.
The trench to be excavated and size of footings would vary with the total load to be transferred to ground and the soil-bearing capacity. With all this background, it is surprising to know that most house owners get no drawings done for the foundation, with the mason doing what he knows. So, the first step is to appoint an innovative structural
If the idea is to transfer load to ground, why not an arch action? We all have seen long railway bridges across rivers with big arches and few pillars, where the arch passes on the weight to pillars. Can there be such arches below the building which pass on the load to fewer points in the ground? In all the older civil text books, there used to be arch foundation details, yet of late, its popularity has drastically reduced. Architect Mohan Rao recently worked with this idea and has once again proven the validity of arch foundation, demanding less materials and cost.
It requires certain calculations about the ground arches, their width, curvature rise, and arch materials. Instead of a full 3’x3′ trench, the excavation itself is done in arch forms, a series of them to cover the full wall length, and each curved mud profile takes a natural arch.
The springing points of arches can also be the pillar points, if needed. With reducing application, arch foundation faces the fear of extinction, despite all its advantages. It’s time we revive it.
Boulder-packed foundation is an easy and widely applicable solution
Crucial factor: Soil condition has its impact on the foundation
This is the third in the ‘Green Sense’ series focussing on topics that could help one follow some rules or get ideas for an eco-build. Getting ecologically conscious or bringing in sustainable architectural methodologies, the column speaks of green sensibilities and makes you contemplate on matters for your construction.
If you dig around the walls of your ancestral home, you may not see any foundation steps or size stones. If you enquire at most century-old villages of Karnataka, you may hear about foundations in laterite, bricks, stone slabs or even timber, with mud or lime mortars. If you check out Laurie Baker on websites, possibly you would come across the term ‘boulder-packed foundation’.
Foundation is the first action at site, but should be the last design decision. The first part we are aware of, but the latter part we never thought of. Surprised? We all know that the soil condition has its impact on the foundation, which the engineers attend to. Besides, the invisible foundation is influenced by all the visible parts of the building – if flat roofs behave one way, the sloping roofs demand a different approach. We may or may not need columns. How about curved roofs over large areas without any columns? When walls are not in one alignment, the foundation can be used to tie the walls. Foundations cannot be done only in one way, in standard sizes.
So, if we know what we are designing for, the foundation can be optimised. However, most Bangalore houses start with the standard trench 3’x3′ even before the design is finalised. We hope to save time by doing earth-work during designing, but waste resources by unwanted dimensions and avoidable locations. As such, most houses end up with over designed or the standard foundations, without considering the alternatives.
Boulder-packed foundation is an easy and widely applicable solution. It may not be safe to apply it in very loose soil or water-logged areas without expert advice, where boulder packing may have to be combined with soiling or plinth beam, as the case may demand. Once the foundation trench is dug as per size, place a levelling course of stone slabs or plain concrete at the bottom. Build up the foundation in courses of irregular stone boulders packed with sand and layers of only sand to the full width of trench up to the ground level. Then use undressed stone with external edge along the wall edge. Materials specific to the place can replace stone.
Most buildings built before the British stand on boulder-packed foundation, even today.
People scoff at buildings with natural materials but realise their value later
To think and feel green is in itself a socially responsible attitude and this sense is what is going to help people get into the eco-build mindset. Ecological, sustainable, green buildings are much discussed in the media today. The factors that make up all this is an impossible gather of ideas, owing to the magnitude of the subject. More so, ‘going green’ is area specific too, making one rule be a misfit elsewhere. Therefore, local wisdom would be a vital factor to be considered in the green principle guide.
Plan-designs or materials, the multiplicity of choices can overwhelm one into hurriedly choosing some wrong ideas. Just what is it that commoners need to know for having a socially conscious, responsible building?
This basic sense is what the new column ‘Green Sense’ in PropertyPlus is trying to attempt, while making one understand simple principles that go a long way in adhering to sustainable practices.
Why do people take all the trouble to design against nature and then struggle to live with all the problems, must be among the top questions of our times. Most builders and designers believe that it is difficult to design with nature or even with natural materials. Of course, it is a myth, like many other myths about eco designs.
Professionals may not agree in public, but it is a fact that designing a house is half-based on common sense. There is a designer within you, I and everyone, for all animals have been endowed with an impulse to create a shelter. Look at those lovely nests of the weaver bird, tall anthills of termites and the little bowl dug into ground by the street dog.
We all manipulate our immediate surroundings to intervene with the harsh climate around us to protect ourselves. However, while protecting the self, no animal damages the context. Only we the human beings know both — how to design and how to damage. The former is necessary and the latter avoidable.
Only a myth
Natural materials often last only for a short period, leading to the myth about their negation in construction. Some minimalist processes can infuse longevity in mud, turn them into burnt clay, with which Harappan structures were built and can be seen even now thousands of years later.
A simple admixture of cement and stone dust stabilizes mud into a strong material. Treated wood can last for ages, as proved by millions of specimens of timber architecture around the world. Durability of stone need not even be mentioned here. Strangely, well-maintained thatch roofs too have lasted many generations. If so, why do people scoff at buildings with natural materials?
“Eco-friendly buildings are for the economically poor” is a statement I heard about a decade ago. Though it was shocking to hear this, it reminded me about how people initially rejected Laurie Baker’s low-cost designs, but when his designs became iconic, sought them “at any cost”!
Air conditioning is not an indicator of affordability, but of lack of effective planning; high life cycle cost may not be a matter of pride, but of continuing financial drain; and we place exhaust fans in toilets because we design such that the foul air refuses to exit. Incidentally, if we can save money by being eco-friendly, why not?
Construction activities such as buildings, roads and infrastructure contribute to around one-third of the global greenhouse gas emissions
Green buildings are much discussed in the media today. The factors that make up all this green is an impossible gather of ideas, owing to the magnitude of the subject. More so, ‘going green’ is area-specific too, making one rule a misfit elsewhere. Therefore, local wisdom too would be a vital factor to be considered in the green principle guide.
Plan-designs or materials, the multiplicity of choices can overwhelm one into hurriedly choosing some wrong ideas. Just what is it that commoners need to know for bringing in worthy ideas for having a socially conscious, responsible building? This basic sense is what the new column ‘Green Sense’ in PropertyPlus is trying to attempt, while making one understand simple principles that go a long way in adhering to sustainable practices.
Creation is such a wonderful word. All of us believe we are creative; we can create corporate wealth, an iconic building or a signature wall mural. Global economy, web world, climate change and hungry society are also our creation. During these self-congratulations, the only thing we tend to forget is that we too have been created; as such, we owe something to our creator — Mother Nature.
We human beings are not greater than the earth to say, “Let us save the earth.” Instead, if at all there is a saviour for us, it is the earth itself, which we are destroying. Construction activities such as buildings and roads contribute to around one-third of global greenhouse gas emissions, becoming the single largest cause for climate change. However, buildings are inevitable for our shelter, security, activity and image. Even the smallest act of construction consumes resources and damages nature; hence no construction can be certified as good for earth. If so, why do we hear so many words and terms referring to alternative building ideas, which claim to save the earth?
“Alternative” is a loose term to sum up all that architects, engineers and builders intend to do towards reducing the damage we create by building. As we now know, we can only minimise these damages, not totally eliminate them. Hence, when we say eco-friendly, it expresses our concern for nature, reducing the negative effects of our acts.
Most of us regard architect Laurie Baker as the father of cost-effective construction in India, which is also being sensitive to resources, hence eco-friendly. ‘Green building’ is among the new words buzzing around us, promoted by American companies, attempting to reduce cost, consumption and embodied energy by large buildings which are high-end energy guzzlers. The rating system called LEED has also been accordingly promoted. Our own Indian standard called GRIHA is also available now to evaluate a construction.
To apply the quote by Gandhiji, if only we can build just for our need, and not for our greed, also build for our living and not for our luxuries, then the earth might not have suffered so much. To this end, already many ideas have been tried, efforts have been spared and new architecture has been suggested. Let us share them between us and save us all.