Approximate estimate is preliminary or rough estimate. This is made to find out an approximate cost of construction in a short time. Such an estimate is prepared adopting different methods for different types of works.
Approximate estimate for main parts of a project as for buildings, services like sanitary, water supply, drainage, electrification, boundary wall, roads, if any, cost of land etc. are made separately. At the end a General Abstract of cost is drawn.
Provision of contingency @ 5 per cent to 10 per cent is added with the Abstract which is the total approximate cost of the project.
Benefits of Approximate estimate:
To investigate feasibility:
To save time and money
To investigate benefit and comparison of cost with utility.
Adjustment of planning
To obtain administrative approval
For insurance and Tax-schedule.
Approximate Methods of Estimating for Building The following are the common methods used to estimate construction cost of buildings.
Plinth area or square meter method Cost per square foot: If the total cost of the house is divided by the square feet of floor areas, the cost per sq. ft is determined.
Cubic rate or cubic meter method Cost per cubic foot: It is ascertained by floor area x height to the eaves + floor area x ½ of height from the areas to the peak of roof. Divide the total cost of the house by the figure so secured.
Cost per room: Total cost of the house is divided by the number of main rooms in it i.e. living room, dining room, kitchen & 2 bed rooms.The cost of the subsidiary rooms such as bath room, closets & hall is included in the estimated cost of the main room.
Open porches cost about ? of the finished house.
Enclosed porches ? rd of the finished house.
Garages of building ½ of the finished house
Cost of building fluctuate widely from time to time and from locality to locality & is due to the relative availability of material and to differences in wage rates.
Accurate or Detailed Estimate For Building: Accurate estimate is prepared by Detailed Estimate Method and it is done by Civil Engineers.
How to prepare a detailed Estimate
Detailed measurements of every item such as excavation for foundation, concreting, masonry etc.
Other part consists of an abstract quantity of various items and the rate of each item. When the quantities are multiplied by their respective rates and the whole thing added up you get the total cost and add 5% for contingencies to their total
Measurement Form:
Item No.
Description or particulars
No.
Length
Breadth
Height or Depth
Content or Quantity
Various heads of items to be estimated:
Cleaning site i.e. cutting trees digging the roots, ant hills etc.
Excavation for foundation
Filling foundation trenches with concrete
Foundation masonry – with stone or brick in mortar
Plinth masonry
Super structure masonry of exposed wall
Partition walls
Doors of teak or other wood with or without ventilators.
Windows of teak or other timber with iron bars
Cupboards of teak with shelves with brass handles & other fittings
Glazed wall tiles to wall in bath, W.C, kitchen etc
Water tank on top of roof
Complete equipment of W.C
Clothes drying lines – water supply & drainage pipes
Compound wall, drive way & foot paths
Electric wiring from street mains to various rooms
Planting trees & seedlings and flower beds.
The total estimate is the summation of
cost obtained by adding all items priced,
Contingencies 5 per cent and
Work charged establishment 2½ per cent a detailed estimate is prepared.
For big projects an amount 1 per cent to 1½ per cent of the estimated cost is also provided to purchase special Tools and Plants for specific purpose of the project.
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