ESTIMATION 13.pptx

ESTIMATION Estimate is a document which furnishes the quantities of different works involved, their rates and the expenditure anticipated in a project. Estimation or Estimating is the process of calculating the quantities and cost of various items of works involved in the project. This is generally...

ESTIMATION Estimate is a document which furnishes the quantities of different works involved, their rates and the expenditure anticipated in a project. Estimation or Estimating is the process of calculating the quantities and cost of various items of works involved in the project. This is generally done with reference to the already prepared plan and sectional elevation of the structure. ESTIMATION  The estimate may be prepared approximately as a preliminary estimate by various methods with out going details of the different items of work ,to know the approximate cost or rough cost.  Accurate estimate is prepared in detail item –wise by detailed estimate Types of estimate 1. Preliminary estimate or Approximate or Rough estimate 2.Complete estimate 3. Detailed estimate or item rate estimate 4. Revised estimate 5. Supplementary estimate 6. Annual maintenance or repair estimate ESTIMATION Rough estimate The estimate which is prepared using any rough method to get the approximate cost of construction. Complete estimate The estimate includes, in addition to the cost of construction, the cost of land, the expenses towards surveying, preparation of plans and estimates, getting the plan approvals, legal assistance, registration of documents, payments of taxes and service charges to the concerned departments.  ESTIMATION Detailed estimate The estimate which provides the item wise quantities of works, item wise unit rates and item wise expenditure anticipated in the project/construction. Revised estimate When any major change or alteration is made in the plan/structural arrangement, with or without affecting the estimated cost… When the estimate cost is likely to exceed by more than 5% during execution due to increase in the cost of materials and labour or due to alterations in the items of works. ESTIMATION Supplementary estimate. During the execution of work, sometimes, it might be found necessary to do a few extra items of works which were not included in the original estimate. At the same time , there might not be any change in the quantities/rates/amounts of the items already considered in the original estimate. ESTIMATION Annual maintenance estimate. The structures once completed are to be properly maintained for its effective functioning and durability. Maintenance works such as white washing, painting, cleaning etc., are to be carried out periodically. For such expenditures, annual maintenance estimates are being prepared by the concerned department for getting the allocation of fund made in the annual budgets. ESTIMATION Repair estimate Such as replacement of roof covering ( A.C sheets, tiles, etc.,), decayed wooden items, corroded steel items, pipes, old wire, switches etc., Repairs of cracked roofs, walls, sunshades, shelve etc., Renewal of broken glass/ window shutters, wash basin, water closets, flooring etc., Are often found necessary to keep the structure in good condition. Repair estimate are being for such repair works whenever they are to be taken up. METHODS OF APPROXIMATE ESTIMATION  SERVICE UNIT METHOD  PLINTH AREA METHOD  CARPET AREA METHOD  CUBE RATE METHOD.  TYPICAL BAY METHOD.  ROUGH QUANITY METHOD. The following things shall be included in the plinth area: 1. all floor, area of walls at the floor level 2. internal shafts for sanitary installations provided these do not exceed 2 sq.m in A/c ducts, lifts etc., The following things shall not be included in the plinth area:  Area of loft  Internal sanitary shaft ( more than 2 sq.m)  Un enclosed balcony  Towers, domes, projections etc.,  Architectural bands, cornice etc.,  Sunshade, vertical sun breakers or louvers projecting out., . Floor area is equal to plinth area minus area occupied by walls.  Circulation area Circulation area is the floor area of verandahs, passages, corridors, balconies, entrance hall, porches, stair cases etc., which are used for movements of persons using the building. 1. Horizontal circulation area 2. Vertical circulation area HCA – This may be 10 to 15% of the plinth area of the building VHA – Space occupied by stair, lifts, this may be 4 to 5% of the plinth area of the building. Carpet area  Carpet area of building is the useful area or liveable area.  This is the total floor area minus the circulation area, verandahs, corridors, passages, stair case, lifts, entrance hall etc., and minus other non useable areas as sanitary accommodations ( bath & w.c )  Carpet area should exclude the kitchen, pantry, stores and similar other room which are not used for living purposes.  The carpet area of an office building may be 60 to 75 % of plinth area of the building with a target of 75 %.  The planners should aim to achieve a target to 75 % of the plinth area.  The carpet area of residential building may be 50 to 65 % of the plinth area of the building with a target of 65 %..  The actual expenditure of an residential building 127 sq.m is found to be Rs. 6,35,000/- in which 60% is towards the cost of the material and the remaining is towards the cost of labour. It is now proposed to construct a similar office of same height and specification with a plinth area 154 sq.m at a place where the cost of materials is 10 % more and cost of labour is 20% less. Estimate appox., cost of the proposed ANSWER  Total cost of existing office building = Rs. 6,35,000 /-  area of existing building = 127 sq.m  rate = 635000 = Rs.5000 per sq.m  127  cost of materials = 0.6 x 5000 = Rs. 3000 per sq.m  Cost of labour = 0.4 x 5000 = Rs. 2000 per sq.m  Increase in cost of materials = 10%  Decrease in cost of labour = 20 %  Plinth area rate for proposed office = 1.1 x 3000 + 0.8 x 2000  = 3300 + 1600 = 4900  Appox., cost = 4900 x 154 = Rs. 754600 SPECIFICATIONS  Is an important document attached with a tender form/contract agreement which in most cases controls the quality of materials and works.  Sometimes , specifications mat used to describe matters which could not be explained clearly by drawings/ sketches. This chapter explains the different types of specifications and their necessity. SPECIFICATIONS  For each proposed work, drawing are prepared to explain the details of foundations, basement, superstructure, roof , floors, joinery etc., whatever attempt is made to furnish complete working drawings, it becomes necessary to describe the drawing in detail.  This description in words without sketches and sometimes with line sketches giving details of standard materials, method of construction and the requirements of workmanship of construction etc., is called specification….. SPECIFICATIONS  Objectives ……  The specifications define the quality of materials and workmanship. Hence this will help the contractor to quote correct rates for the different items of works.  The information contained in the specifications will serve as a guide to the contractor as well as the supervising staff during the execution of the work. TYPES OF SPECIFICATIONS  General specifications  Detailed specifications  Standard specifications General specifications  General specifications gives the nature and class of work and materials in terms of various parts of work, from the foundation to the superstructure.  These general specifications do not form part of the contract document. Detailed specifications  It’s a part of the contract document.  The detailed specifications of an item of work specifies the qualities and quantities of materials, the proportion of mortar, workmanship, the method of preparation and execution and method of measurement.  Detailed specifications are written to express the requirements clearly in concise form avoiding repetition and ambiguity. Standard specifications  The standard specifications SAVE TIME, LABOUR, STATIONERY EXPENDITURE etc.,  For example, specifications for earthwork, concrete works, brickwork etc.,  The department developing their own standard specifications repeatedly they are referred to the departmental standard specification.  Public work department ( P.W.D)  Central Public work department ( C.P.W.D)  Railway department.