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Thursday, September 29, 2011

House ponds and Swimming pools for Kerala Houses

A 'Kulam' or house pond used to be an integral part of Kerala Houses since time immemorial. This is where the daily rituals of bathing, washing and even 'Sadakam' for the musically inclined was performed. Apart from providing the source of water for these daily activities, the 'kulam' also provided adequate exercise to the men, women and children of the household, one factor that is grossly lacking in today's lifestyle.
Now, more and more home builders are opting to have a swimming pool constructed as part of their house. Swimming pools come in various sizes and budgets. Normally a residential swimming pool ranges from 4m x 8m, 5m x 10m, 6m x 12m to 7m 14m, depending on the budget and available plot size. The shape varies from rectangular to irregular. The cost of a swimming pool depends on location, design, size, materials used, permit fees, local labor costs, depth, water features, additional accessories such as diving boards, slides, pumps, filters, automated filtration, heating, electronic chlorinators, automated cleaning systems, wireless remote controls, design add-on options such as waterfalls, landscaping, decking and other such details.
Almost any pool shape can be designed to fit your property and your specifications.
There are three types of swimming pools commonly built, one is the standard skimmer design, second is the rimflow and the third is the infinity. Cost of each design varies from one another. 
The swimming pool is going to be the water recreation area in your compound. A place where you will entertain friends and family. A place where children and grandchildren will meet and play. 
You should first determine what kind/size of pool is appropriate for you and your family, in terms of shape, style, etc...It really depends on how you plan to use your pool. If exercise is the priority, then a rectangular pool that facilitates swimming laps is appropriate. If you desire a pool that reflects a backyard oasis that is the perfect setting for entertaining, relaxing and overall enjoyment then a Freeform designed pool is probably most suited.
A regular residential swimming pool in Kerala will not cost much to maintain. The level of involvement in maintaining your pool is up to you. You can either opt to do the maintenance yourself or engage the swimming pool contractor to do it. You can negotiate a maintenance schedule with your swimming pool contractor to keep your pool in peak condition throughout the year.
Unlike earlier House Ponds, the Swimming pool does not have a ground water circulating system. The water in the pool is pumped in and stays there until it is mechanically removed. With modern swimming pool filtration equipment now available, you can use the same water even up to 2 years as long as you follow the correct water treatment and filtration procedures. Although this may not seem as an ideal situation for us Keralites who have a strongly embedded 'fresh water' concept; swimming pool water filtration systems have been found to be efficient in maintaining clean and safe levels over an extended period of time.

Friday, September 23, 2011

M-Sand as a substitute for River Sand in Construction

Procuring River Sand for Concrete is one of the major problems a House builder faces in Kerala. With severe scarcity and more restrictions imposed by the government on dredging of river-beds, we have to look at alternative materials like Quarry Dust or Manufactured Sand. While Quarry dust is a by-product of stone-crushing, Manufactured Sand is made specifically to be used in Construction Concrete.

Manufactured Sand or M-Sand, as it is more popularly known, is made by powdering hard granite rocks using heavy machinery. It's particles are cubical in shape and finely graded and hence provides greater durability and higher strength to concrete by overcoming deficiencies like segregation, bleeding, honey combing, voids and capillary.

As M-Sand is made specifically for construction, it has many qualities that are superior to River sand or Quarry dust. The particle shape of the aggregates is very important. Sand having cubical particles provide higher tensile and compressive strength to the concrete. While clay and slit is present in River sand which may affect the strength of concrete, M-Sand is free of these impurities. Also, consistency of quality can be achieved in Manufactured Sand, while River Sand has varying quality in different batches.

River sand has to be sieved to remove stones, slit and clay. Average wastage of sieving is about 35% in materials and extra labour cost is incurred.  Whereas M-Sand is ready-to-use-sand with no wastage since it has no organic impurities.

Properties of Manufactured Sand-

Greater Durability
M-Sand has balanced physical and chemical properties that can withstand any aggressive environmental and climatic conditions as it has enhanced durability, greater strength and overall economy.  Usage of M-Sand can overcome the defects occurring in concrete such as honey combing, segregation, voids, capillary etc.

High Strength
The superior shape, proper gradation of fines, smooth surface texture and consistency in production parameter of chemically stable sands provides greater durability and higher strength to concrete by overcoming deficiencies like segregation, bleeding, honey combing, voids and capillary.

Greater Workability
The crusher dust is flaky and angular in shape which is troublesome in working. There is no plasticity in the mortar which makes it even difficult for the mason to work, whereas the cubical shape with grounded edge and superior gradation gives good plasticity to mortar providing excellent workability.

Offsets Construction Defects
M-Sand has optimum initial and final setting time as well as excellent fineness which will help to overcome the deficiencies of concrete such as segregation, bleeding, honeycombing, voids and capillary.

Usage of M-Sand can drastically reduce the cost since like river sand, it does not contain impurities and wastage is NIL.  In International Construction Scenario, no river sand is used at all, only sand is manufactured and used, which gives superior strength and its cubical shape ensures significant reduction in the cement used in the concrete

M-Sand is the alternative to river sand.  Dredging of river beds to get river sand will lead to environmental disaster like ground water depletion, water scarcity, threat to the safety of bridges, dams etc.

Beside with the Government contemplating ban on dredging of River beds to quarry river sand, as part of the growing concern for environment protection, M-Sand will be the only available option.

Information- Courtesy: POABS

Saturday, September 10, 2011

Advantages of Filler Slabs

In a simply supported RCC slab, the upper part of the slab is subjected to compressive forces while the lower portion is subjected to tensile forces. Concrete is very good in compression while it is weak in tension. Hence the steel reinforcement is placed in the tension zone. The concrete in this portion is only for holding together the steel reinforcement and has no structural purpose. This 'un-productive' concrete can be replaced by a 'Filler' material which will reduce the weight of the slab and also reduce the cost by reducing the amount of concrete used. Also, since the weight of the slab is thus reduced, lesser steel is also required for reinforcement, further reducing the cost.
  • There is no reduction in the structural strength of the slab at all and it will act as a normal load bearing slab.
  • Common filler materials are light weight materials like Mangalore tiles, clay pans, bricks, waste bottles, coconut shells, thermocol etc.
  • Reduces the cost of the slab by around 25-30%
  • Creates interesting designs and patterns on the ceiling
  • Helps in better thermal insulation of the slab due to the air pockets present.
  • Reduces the load on the foundation

Reinforced concrete
The filler slab is based on the principle that for roofs which are simply supported, the upper part of the slab is subjected to compressive forces and the lower part of the slab experience tensile forces. Concrete is very good in withstanding compressive forces and steel bears the load due to tensile forces. Thus the lower tensile region of the slab does not need any concrete except for holding the steel reinforcements together.

Therefore in a conventional RCC slab lot of concrete is wasted and it needs extra reinforcement due to added load of the concrete which can otherwise be replaced by low-cost and light weight filler materials, which will reduce the dead weight as well as the cost of the slab to 25% (as 40% less steel is used and 30% less concrete).
The filler slabs also result in fewer loads getting transferred to the load-bearing walls and the foundations. The air gap in between the tiles makes it a good heat insulator and the ceiling looks attractive as well.

The mechanism 
The filler slab is a mechanism to replace the concrete in the tension zone. The filler material, thus, is not a structural part of the slab. By reducing the quantity and weight of material, the roof become less expensive, yet retains the strength of the conventional slab. The most popular filler material is the roofing tile. Mangalore tiles are placed between steel ribs and concrete is poured into the gap to make a filler slab. The structure requires less steel and cement and it is also a good heat insulator.

Strength of filler slabs.
Conventional tests by different institutions and laboratories has proved the load bearing capacity of filler slab and found it no less in performance from the conventional R.C.C. slab. Since filler roof tiles are firmly bonded to and covered by concrete, it does not collapse under the impact of say, a coconut falling on the roof.

Leak proofing filler slabs.
With proper supervision and workmanship, leaks can be avoided. The chance of a leak in a filler slab is much the same as the conventional R.C.C.slab.

Saving on cost 
The savings on cost can be from 15 per cent to 25 per cent. But designing a filler slab requires a structural engineer to determine the spacing between the reinforcement bars.
Other favored filler materials include clay pots, stabilized mud blocks, brick or brick panel, broken pieces of cement blocks and even coconut shells. The quantity of concrete in the tension zone of the slab that can be replaced by a filler material depends upon the shape of the filler material and the thickness of the solid slab.

Thermal insulation
The air pocket formed by the contours of the tiles makes an excellent thermal insulation layer. The design integrity of a filler slab involves careful planning taking into account the negative zones and reinforcement areas.

Patterned ceilings 
Filler slabs provide aesthetically pleasing patterned ceilings. In most houses, the filler material is left open without plastering to form aesthetic design symmetry but some residents prefer to cover the space with Plaster of Paris coating.

Thus the filler slab as the roof has the following advantages:
  • Consumes less concrete and steel due to reduced weight of slab by the introduction of a less heavy, low cost filler material like two layers of burnt clay tiles. Slab thickness minimum 112.5 mm.
  • Enhances thermal comfort inside the building due to heat-resistant qualities of filler materials and the gap between two burnt clay tiles.
  • Makes saving on cost of this slab compared to the traditional slab by about 23%.
  • Reduces use of concrete and saves cement and steel by about 40%.

Tuesday, September 6, 2011

Low-Cost House: 2 Lakhs budget

Alappuzha, Cherthala

We are planing to construct a low cost house - Maximum 2 Lakhs budget. Is it possible in the present situation?


We appreciate your effort in trying to construct a house of Rs 2 Lakhs budget. Before you embark on this mission, do prepare mentally for the extra hard work you need to put in planning and budgeting all the activities to be performed right from design stage to completion.

First, what you need is a very cost effective design that incorporates all your requirements without over-utilizing space or structural elements. The design has to be worked and re-worked until it is Cost-effectively Optimized. Take extra time and effort in finalizing the design.

The next step is to decide on the materials to be used. With a constrained budget, you cannot afford to have a margin of error. Find the most cost-effective building materials in your area. It would vary depending on the location of your residence. Eg- Laterite Stones are Cost Effective in the North Kerala Malabar Region. Do research on the most cost-effective wood, flooring, roofing and other materials in your region.

Study your Site Conditions to avoid any unexpected future setbacks. Do make sure that the Site did not previously have wells, ponds or clay fields that were filled without proper soil consolidation. Use the most appropriate foundation depending on the soil condition.

Appoint a Contractor who has previous experience in Low-Cost House Construction. You may contact the local branch of Cost-effective Construction Agencies like Nirmiti, Costford, Habitat etc. Have long and extensive discussions with the Contractor and be very clear about the various stages of construction and the time and cost incurred at each stage.

Once Construction starts, stick to the schedule without a break in the work. Any delay may further increase the cost and material wastage. In short, constructing your residence on a tight budget requires meticulous planning and execution.

To get a Cost-effective Design for your site, send us your Site Plan and List of Requirements as in>>