Good planning makes like simpler when you build your home. The first step is to allocate funds for plot purchase and home construction separately from your total budget.
Once you have finalized the plot you can meet professionals like Architects/Engineers/Contractors, etc. for design and drawing of your home. He should be registered with the Municipal Authority. He will provide you with the plan, elevation, side and rear views of your proposed house along with steel reinforcement details.
If you are engaging a contractor then specify the terms and conditions in writing to him. You must specify the construction schedule, payment terms, quality of work, quality of material like cement, sand steel, finishing & fittings, electricals, sanitary items, etc. in the contract specification.
Estimates will depend on the actual design and drawing of your home and market rate of materials and labour. However, an approximate estimate can be done before that. Construction cost depends on the quality of construction and the finish you want to have. Just to illustrate – a high class finish construction can cost you as much as 50-100% higher than an economy class finish.
While you can always make a rough estimate of the cost using your judgement, it is always advisable to take professional consultation on budgeting of home construction. Generally, construction costs can be divided into material cost, labour cost and other expenses in the ratio of 60:30:10 respectively.
Cement is an important construction material and when mixed with water and other material like sand, aggregates (gitti), etc. binds them together. It is used in concrete, brick work and plaster work. Good quality cement should feel smooth when touched or rubbed between fingers. If a small quantity of cement is thrown into a bucket of water it should sink and not float. It should be free of lumps. Cement should always be kept free from moisture and water. Its storage shed should have finished floor raised atleast 150mm from ground level and should have airtight doors and windows.
Rebars is the most important component of RCC structure. Concrete alone cannot take tensile loads. Steel rebars are cast into concreting to carry tensile loads. Generally rebars available in the market are manufactured through TMT route. However, the consistency in the strength of the rebar is determined by the input material. If it is manufactured via scrap route the consistency of strength along the length of the rebar is not there.
For any steel rebar weight per running metre is equal to d2/162 Kg, where d is diameter of the rebar in mm. for example, 10 mm diameter rebar will weigh 10 X 10 / 162 = 0.617 Kg/m. In India, quality and properties of steel rebars are governed by the code IS:1786 given by Bureau of Indian Standards (BIS).
|Strength and elongation of rebars must comply the following standards|
|Grade of Rebar||Minimum Yield Stress (N/mm2)||Minimum Ultimate Tensile Strength (N/mm2)||Minimum Elongation %|
|Fe 415||415||10% over yield Stress but ≯ 485 N/mm2||14.5|
|Fe 500||500||8% over yield Stress but ≯ 545 N/mm2||12.0|
|Fe 550||550||6% over yield Stress but ≯ 585 N/mm2||8.0|
|You should ask for the steel supplier to verify the quality.|
Water is an important as any other material mentioned above. It helps cement in hydration and distributes the cement evenly. It should be free from any salt, silt, organic compound, etc. Potable water is recommended for the purpose of construction and curing.
Foundation Work :
For designing strong and economical foundations, soil testing is very important. Bearing capacity of the soil also called soil strength has impact on the way foundation should be laid. For instance, in case of black cotton soil or soil types with low load bearing capacity, pile foundations or continuous foundations are common practice. In case if back filling is required, mooram is the best material. If it is not available then either good quality clay or sand may be used. Filling should be done in layers of maximum 6 inch thickness, sprinkling each layer with water before compaction.
Steel Reinforcement :
Plain concrete without reinforcement is like a body without bones. Reinforcement through steel rebars is one of the best forms of reinforcement to take care of all kinds of stresses generated in structure. It is advised that same type and grade of steel should be used in a structural member. Always ask your engineer to do the reinforcement detailing for earthquake resistant construction, if your house is located in seismic zone III, IV, or V. You should make sure to take the steel reinforcement detailing from your engineer. It is called Bar Bending Schedule (BBS). This schedule contains all the details of size, shape and dimension of rebars to be cut. A good BBS will help you in buying the rebars in most economical quantity and minimize steel wastage.
Proper grade of concrete should be developed using the adequate quantities of cement, sand, stone chips, and water. For example, to prepare M 20 (1:1, 5:3 approx.) mix of concrete, you require one bag of cement, 1.5 boxes of sand, 3 boxes of stone chips and 21 litres of water. A mixer should be used to ensure uniform distribution of the material.
Concrete pouring should happen within 30-60 minutes of preparation. It should be poured in layers without breaking the continuity with maximum free fall of concrete not exceeding 1.5 metres. Lastly, compaction around steel bars and the corners of the structure should be carried out using vibrators.
Curing is the final step in completing RCC structure. It prevents moisture loss from the concrete or mortar and maintains the required humidity for reaction of cement in achieving its strength. It should be started after 12-24 hours on drying surfaces and should be continued for a minimum of 7-14 days.