Save time and money with these three construction techniques, says Achyuta Reddy Pannala
India in the last few decades has made many technological advances in many fields. However, there is one industry that has not changed much – construction. We are still using the age-old methods in the way we build our homes/apartments. Our mindsets have not changed when it comes to accepting newer trends and materials in building the dwellings where we spend our lives. Although the way the style and facades have changed the crux of the building - the structure, the walls, the cement plastering is still the same.
We are still employing the same old laborious and time consuming methods of building the walls brick by brick and then plastering the surface entirely floor after floor. Finding skilled masons to do this is becoming a challenging task. Add the Supreme Court of India’s order on restrictions on sand mining, and we have a real situation at hand. Non availability of sand is hindering the speed of projects.
After observing the construction techniques of the west, in comparison to the Indian methods, I found that there are almost no brick walls and no plastering in many developed countries. Particularly in the US, forget about the availability of the materials, you cannot employ people to sit and plaster the whole surface – it will be expensive due to their labour costs. Even in India the labour costs have risen by 100-200 per cent in just two-three years. They may even go up further.
So what are the remedies? Simply adopt the construction methods followed in the West or absorb whatever is applicable to our conditions. For example, nailing a sheet rock (gypsum board) on the interior walls can eliminate the need for plastering.
Secondly the concept of building ‘green’ is catching up in India. Use of environmental friendly material is promoted by organizations like IGBC (Indian Green Building Council). Traditionally, Indian building materials have been rock, mud brick or cement blocks, concrete and cement mortar. All these materials have the tendency to absorb the heat during the day time and radiate it back into the building raising the temperatures inside, increasing the energy consumption in the building.
Here are a couple of methods that could work for Indian conditions. All these construction methods utilise EPS (expanded polystyrene (or thermocol as called in India) an excellent insulator against heat and cold. EPS in India is predominantly used as a packaging material but not as a building material. The web site www.eps.org describes EPS as a building material. When made at higher densities, EPS becomes very rigid and strong to hold concrete, cement mortar etc. EPS used for packaging purposes is manufactured at very low densities and breaks easily, unlike the one made for construction use.
EIFS (External Insulation and Finish System) : Or you may want to call it as 'Synthetic Plastering' which is meant for the exteriors of the buildings. EIFS adds the values of insulation and aesthetics to the building. Plastering can be completely eliminated for the exterior using this system. Invented in 1960s and used extensively since then, this system has been included in the building codes of the US making it mandatory for every home.
EPS sheets at desired density (normally 20kg/m3 and higher is recommended) and thickness are first attached to the outer surface of the building. A polymer mixed cement called the 'Base Coat' is used as an adhesive while finishing the sheets to the exterior of the walls. In addition to the adhesive, special fasteners can be used to hold the sheets attached to the wall surface. After the entire surface is fixed with the EPS sheets, the surface is then rasped for any mis matches at the joints or undulations on the surface. Then the same Base Coat is applied on the entire surface of the EPS using a trowel. We trained some regular painters who apply the wall care finishes like Alltek or Birla Putty and they learnt doing this within no time. While the surface is still wet, a fiber wire mesh is placed on the base coat surface. Fiber mesh gets stuck to the surface very easily. Another coat of 'base coat' is applied on top of the wire mesh evenly to embed the mesh completely in the base coat. The fiber wire mesh reinforces the surface of the EPS. After 24 hours the surface hardens and becomes almost like a cement plastered wall surface. Then exterior primer is applied on this surface. The second main component of this system, the finish coat is an acrylic material which gives a textured appeal to the wall. Acrylic as against the cementitious textures prevents the crack formation on the surface. The combination of the finish coat on top of the base coat works as water proofing layer as well. One other major advantage we have in the finish coat is that we can eliminate the painting completely. The color pigments of the desired color choice can be directly mixed in the finish coat before applying. When the finish coat is troweled on, it will get the color automatically. There is no need to hold the brush and paint the surface. Imagine the savings in painting time. Especially for multi storied buildings EIFS works out to be far better than plastering it and then painting the traditional way. Most of all, you are insulating the building which results in energy savings for the life of the building.
There is no need to water cure the surface unlike the cement plastering. You have savings in water, electricity and labor by employing EIFS. Not just the plain surface, many elevation features can be incorporated into this system as they can be achieved by adhering the EPS cut sheets or slabs as per the design before applying the base coat. Far superior finish than the regular plastering, embedded color, insulation against weather, water proofing are the main advantages of this system. Of course, it is much faster than the traditional plastering.
EIFS is being used in the US and European countries for decades now. EIFS is proven to withstand harsh weather conditions like heavy rains, snow, heat etc. It is very much suitable for Indian conditions. We are using the materials of PAREX USA a pioneer in EIFS materials. Our team worked on installing EIFS in a red brick pattern, all done with EPS at 'Bhuvana Greens', Four towers of eleven storied each on Sarjapur road, Bangalore.
1- Brick wall
2- Base Coat
3- EPS Insulation Layer
4- Fiberglass Mesh
5- Base Coat
6- Finish Coat
ICF (Insulated Concrete Forms): ICFs are stay-in concrete forms. ICFs are EPS molded box like objects which are open at the top and bottom. The edges at the top and the bottom have interlocking features. When placed one on top of the other, they get locked into each other firmly. ICFs are simply placed one next to the other in a line to form the wall. Next layers of ICFs are placed on the top in a row to make up the wall. Concrete is poured into the cavity of the wall after the ICF are placed to form the wall. Concrete is poured after placing three rows of ICFs each time and continued until the desired height is reached. Time laps is given for the concrete to set before pouring the next level of three rows each time. Rebar can be placed both horizontally and vertically and tied before pouring the concrete. This adds lateral strength to the wall.
After the wall cavity is completely filled with concrete, the exterior and interior EPS surfaces can be finished in many ways. GFRC (glass Fiber Reinforced Cement) finish which uses a fiber wire mesh again can be used to finish the surface of the wall. The cement paste (no sand is used) mixed with a polymer is applied on the surface with a trowel as a thin coat.
ICF walls are very strong as they are filled with concrete. Walls can be easily built employing unskilled labor. Again, plastering can be avoided totally, hence no sand is needed. The concrete poured in ICFs forms a grid structure inside giving substantial strength to the wall compared to the brick walls with many joints. Wall cracks are impossible as the inside of the wall forms as a monolithic structure. EPS layers on both sides of the wall insulate the building. Labor component is substantially reduced in this method and skilled labor are not a compulsion. Wall finish is a painter's job as no plastering is involved.
ICF method of construction is a proven technique for rapid wall building. Huge time savings can be realized in the over all construction. Solid strong walls are possible with an added benefit of insulating the building.
SIPCRETE Walls: The word SIPCRETE can be split into two parts. SIPs or Structural Insulated Panels are wall construction panels made of EPS. 'Crete' represents the concrete or cement mortar. Slabs of EPS at 100mm or 150mm or as per the desired thickness with 3 feet width and required height as length will be assembled with welded metal wire mesh both sides three dimensionally. An automatic weaving machine welds the wire mesh on either side of the EPS slab and cross links are welded from one side of the mesh to the other side, passing through the EPS slab. These panels are erected one next to the other in a line to make up the wall to be built. Starter rebars for upto 2 feet height will be placed into the floor slab or plinth beam at a regular interval. Panels will be tied to the rebars on both sides of the wall at the bottom of the wall to secure it in place. Overlapping mesh is placed at the joints and tied together to cover the joints.
Panels are cut with openings for the door frames and windows where required as per the plan. Supports are placed against the walls to keep them plumb and vertical. Then cement mortar is sprayed-on on the panel surface on either sides. Yes, this is nothing but plastering but mostly done by the sprayer attached with an air compressor. Cement mortar is sprayed by half an inch to one inch as per the requirement. Then the wall surface is leveled and smoothened for a good finish. With one inch cement mortar on either side of the wall, the wall panel becomes super strong and load bearing. This type of walls can be constructed in an already existing RCC structure or the roof slab can be poured after the walls are built. Villas upto two stories can be built without any additional columns or beams as the walls themselves become load bearing.
Even the roof can be built using the same type of panels. A two inch thick concrete slab will be poured on top of the roof panel while the bottom is plastered in cement mortar. SIPCRETE walls are rigid, sturdy and last long. The walls become a monolithic structure as against the number of joints in a brick wall. Most importantly you get an insulated home that saves energy consumption for the life of the building.
Although we are plastering the walls unlike the above two methods, we are eliminating the brick work completely. Employing the sprayer which is very easy to operate, one can plaster the surface of the wall quickly. This system reduces the construction time, saves on labor which can become significant advantage while constructing big buildings. For small villas and homes, RCC structure can be totally eliminated which is direct savings. Even stair cases can be built with an ease.
Although expensive machinery is required to assemble these panels with welded mesh, we invented a cheaper, manual way to accomplish the same results to cut down on the cost of manufacturing these panels. A sample building built for Golden Gate Properties at Liberty Acres gated community at Athibeli, Hosur Rd, Bangalore is available as an example of this system.