Tuesday, September 10, 2013

Hollow Blocks used by SEVAI for the construction of Cost effective Housing



Shelter walls constructed by SEVAI in Trichy slums for fire victims

Cost effective Housing is an appropriate concept which deals with effective budgeting and following of techniques which help in reducing the cost construction through the use of locally available materials along with improved skills and technology without sacrificing the strength, performance and life of the structure. There is huge misconception that Cost effective Housing is suitable for only sub standard works and they are constructed by utilizing cheap building materials of low quality. The fact is that Cost effective Housing is done by proper management of resources. Economy is also achieved by postponing finishing works or implementing them in phases. The building construction cost can be divided into two parts namely: Building material cost and Labour cost. Now in Cost effective Housing, building material cost is less because we make use of the locally available materials and also the labour cost can be reduced by properly making the time schedule of our work. Cost of reduction is achieved by selection of more efficient material or by an improved design.Areas from where cost can be reduced in Cost effective Housing are Reducing plinth area by using thinner wall concept.Ex.15 cms thick solid concrete block wall, Using locally available material in an innovative form like soil cement blocks in place of burnt brick and applying  energy efficiency materials which consumes less energy like concrete block in place of burnt brick. Use environmentally friendly materials which are substitute for conventional building components like use R.C.C. Door and window frames in place of wooden frames. Preplan every component of a house and rationalize the design procedure for reducing the size of the component in the building. By planning each and every component of a house the wastage of materials due to demolition of the unplanned component of the house can be avoided. Each component of the house shall be checked whether if it’s necessary, if it is not necessary, then that component should not be used. Normally the foundation cost comes to about 10 to 15% of the total building and usually foundation depth of 3 to 4 ft. is adopted for single or double store building and also the concrete bed of 6″(15 Cms.) is used for the foundation which could be avoided. It is recommended to adopt a foundation depth of 2 ft.(0.6m) for normal soil like gravely soil, red soils etc., and use the uncoursed rubble masonry with the bond stones and good packing. Similarly the foundation width is rationalized to 2 ft.(0.6m).To avoid cracks formation in foundation the masonry shall be thoroughly packed with cement mortar of 1:8 boulders and bond stones at regular intervals.It is further suggested adopt arch foundation in ordinary soil for effecting reduction in construction cost up to 40%.This kind of foundation will help in bridging the loose pockets of soil which occurs along the foundation. In the case black cotton and other soft soils it is recommend to use under ream pile foundation which saves about 20 to 25% in cost over the conventional method of construction. It is suggested to adopt 1 ft. height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6″ which is normally adopted can be avoided and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%.It is necessary to take precaution of providing impervious blanket like concrete slabs or stone slabs all round the building for enabling to reduce erosion of soil and thereby avoiding exposure of foundation surface and crack formation. Wall thickness of 6 to 9″ is recommended for adoption in the construction of walls all-round the building and 41/2 ” for inside walls.The above suggestions for reducing construction cost is of general nature and it varies depending upon the nature of the building to be constructed, budget of the owner, geographical location where the house is to be constructed, availability of the building material, good construction management practices etc..Govin

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