ESTIMATION AND ITS TYPES - TS

 

INTRODUCTION:

Ø  Estimation or estimating is the process of calculating the quantities of various items of works involved in the project.

Ø  Estimate is a document which furnishes the quantities of different works involved, their rates and the expenditure anticipate in a project.

NECESSITY OF ESTIMATES:

Ø  To know about the approximate cost of the building construction.

Ø  To calculate the tax of the building

Ø  To fix the rent of building

Ø  The know about the various items of works involved in the building construction and arrange the available materials of the construction.

Ø  To arrange the labours of the construction works.

Ø  Take the approval for the government projects.

Ø  To having the loan from the bank.

DIFFERENT TYPE OF ESTIMATES:

Preliminary or Approximate estimate:

Ø  This estimate is prepared to decide financial aspect, policy and to give idea of the cost of the proposal to the competent sanctioning authority.

Ø  It should clearly show the necessity of the proposal and how the cost has been arrived at. The calculations for approximate estimate can be done with the following data.

Ø  The data can be had from a similar construction already complete in the nearby area, executed by the department.

Ø  The following documents should be attached with it.

Ø  Detailed report

Ø  Site plan of the proposal

Ø  It should also clearly mention about the acquisition of land, Provision of electric and water supply etc.

Types of Approximate Estimate:

Ø  Plinth area method

Ø  Cubical content method

Ø  Unit cost (or) service unit method

Ø  Typical bay method

Ø  Carpet area method  and Rough quantity method

Plinth area Estimate:

•        P.A. is approximate estimate

•        Plinth area should be calculated for covered area by taking external dimensions of the building at the floor level.

•        Courtyard and other open area should not be included.

•        For multi storied building Plinth Area for each storey is determined separately.

•        Plinth area rate is known from cost of similar building in the locality.

•        Approx. Cost of the building = Plinth area Rate/ m² x Plinth Area

Cubic Contents Estimate:

Ø  Cube rate estimate is again approximate estimate.

Ø  Cubical content of the building is determined by multiplying length, breadth and height of the building.

Ø  External length and breadth at the floor level are calculated for the purpose.

Ø  Height should be taken from the floor level to the top of roof.

Ø  For multi storeyed building height is taken from floor level of one storey to top of next higher floor.

Ø  Cube rate estimate is more accurate as compared to the plinth area estimate.

 

Unit cost (or) service unit method:

Ø  The unit method of estimating is the simplest and quickest method.

Ø  In this method, the quantity surveyor counts the number of units which are going to be accommodated in a building, for example the number of occupants or main furniture objects used by an individual.

Ø  The number is then multiplied by the cost per unit to get the total estimated cost of the project.

Typical bay method:

Ø  This method is useful and is generally followed in case of building having several bays.

Ø  The cost of the one class room is worked out and then multiplied by the number of bays in that building.

Ø  The extra cost of the end walls and difference in framing. If there is any, should be made, so as to arrive at the correct cost.

Carpet area method:

Ø  Carpet area the covered area of the usable spaces of rooms at any floor.

Ø  It is measured between walls to walls within the building and is the sum of the actual areas of the rooms where you can carpet.

Ø  Floor area = Plinth Area –Area of Walls.

Ø  This includes the floor areas of all rooms, verandahs, passages, staircase rooms, bathroom etc.

Ø  In residential building, the carpet area will be about 55% to 65% of the plinth area.

Annual repair estimate:

Ø  In order to keep building and roads in perfect condition, annual repairs should be carried out as follow: -

ü  In case of a building-white washing, painting of doors and windows, cement plaster repairs (inside & outside), repairs of floors etc.

ü  In no case this annual repair amount should increase more that 1.5 % to 2 % of the capital cost of the building.

ü  In case of a road-filling patches, maintenance of berms etc.

Special repair estimate:

Ø  If the work cannot be carried out of the annual repair funds due to certain reasons resulting in the genuine increase in cost, then special repairs estimate is to be prepared. The reason of increase may be: -

ü  In case of a building-opening of new doors, change of floors, re-plastering walls etc.

ü  In case of roads-if the whole surface is full of corrugation & patches, then the total surface is to be scarified.

ü  The old metal is taken out, consolidation by adding more metal is done and top surface is repainted.

Revised estimate:

Ø  When the sanctioned estimate exceeds by 5% either due to the rate being found insufficient or due to some other reasons, a fresh estimate is prepared which is called a Revised Estimate.

Ø  A comparative statement on the last page of the estimate is attached giving there in the reasons of the increase of cost in case of each item.

Supplementary Estimate:

Ø  This is fresh detailed estimate in addition to the original sanctioned estimate prepared when additional works are deemed necessary during the progress of a work to supplement the original works.

Ø  The abstract of cost should show the amount of the original sanctioned estimate as well as the supplementary amount of the original sanctioned estimate as well as the supplementary amount for which sanction is required.