• Done to find out approximate cost in short time.
• This estimate is prepared after preliminary surveying.
• This estimate is prepared from practical knowledge and cost of similar works.

Types:

a. Unit rate estimate:

• In this method all cost of a unit quantity such as per km for a highway, per meter for span of bridge, per bed for hospital etc. are considered first and the estimate is prepared by multiplying the cost per corresponding unit by the number of unit of the structure.
• Buildings:
  • Per student for school/college
  • Per bed for hospital
  • Per seat for cinema hall
• Road work:
  • Per Km
• Bridge culvert:
  • Per meter length
• Irrigation work:
  • Per Km of canal
  • Per hector of command area

b. Plinth area estimate:

• In this method, plinth area rate of building is adopted from the cost of similar building having similar specification, height and construction in same locality.
• Plinth area = Carpet area + Circulation area + Kitchen/Toilet + Wall

c. Cubic rate estimate:

• This estimate is worked out on the basis of cubical content of the proposed building and then multiplying with rate per cubic content.
• Estimate = Plinth area * height * cubical content rate

1.2 Detailed Estimate

• It is an accurate estimate which contains very detailed data about project variable such as cost/quantity and price.
• The dimension of each item are taken out correctly from drawing and quantities of each item are calculated, abstracted and billed.
• 5-10% of estimated cost for unforeseen item and 2% of work charge establishment should be added.
• This estimate is accompanied by:
  • Detailed report.
  • Detail specification for the execution of work.
  • Detailed drawing (plans, site plan, elevation etc.)
  • Calculation and design of various item such as beams, slabs etc.
  • Schedule of rates followed and premium if allowed.

Factors to be considered for preparation of detail estimate:

• Quantity of materials.
• Availability of materials.
• Transportation of materials.
• Location of site.
• Availability of labor.

1.3 Revised Estimate

• It is also a detailed estimate and is prepared when the original sanctioned detail exceeds by 5%.
• Revised estimate is prepared:
  • When a sanctioned estimate is likely to exceed by more than 5%.
  • When the expenditure of work exceeds or is likely to exceeds by more than 10% of the administrative approval.
  • When there is material rate deviation from original proposal.
  • When sanction estimate is more than actual requirement.

1.4 Supplementary Estimate

It is also a detailed estimate and is prepared when additional work is required to supplement the original work.

1.5 Annual repair and maintenance estimate

In order to keep the structure in proper condition annual repair and maintenance are carried out. The estimate prepared for this purpose is known as annual repair and maintenance estimate.

1.6 Extension and improvement estimate

When some changes and extension are required to be made in the old work, a detailed estimate of extension and improvement work is carried out which is called as extension and improvement estimate.

1.7 Complete Estimate

• In complete estimate following should be included:
  • Cost of land.
  • Cost of preliminary work.
  • Cost of preliminary design, drawing and estimate.
  • Cost of detailed design, estimate, specification and contract documents.
  • Cost of electricity, water supply and sanitary work.
  • Cost of design and supervision charges
  • Cost of external service.
  • Cost of repair and maintenance.

1.8 Split up of cost and building work

a. General split up:

• Labor cost = 30-35% of total cost
• Material cost = 65-70% of total cost

b. Stage wise breakup:

• Construction below plinth level = 10-15% of total cost
• Construction above plinth level = 85-90% of total cost

c. Activity wise breakup:

• Foundation work = 17-18%
• Brickwork/block work = 20%
• Concreting and reinforcement steel = 15%
• Door, windows and ventilation = 12%
• Roof water proofing & finishing = 5%
• Plastering = 5-6%
• Flooring = 5%
• Painting = 2-3%
• Water supply and sanitation = 12-13%
• Other work = 4-5%

References:

• Dutta, B.N. – Estimating and Costing in Civil Engineering, UBS Publishers, New Delhi.
• CPWD (Central Public Works Department), India – Standard Schedule of Rates and Analysis of Rates.
• IS 1200 – Indian Standard for Method of Measurement of Building and Civil Engineering Works, Bureau of Indian Standards (BIS).
• Punmia, B.C. – Estimating and Costing, Laxmi Publications.
• Building Estimation and Costing Notes – Department of Civil Engineering, Pokhara University.
• MoUD Nepal – Standard Norms and Guidelines for Public Infrastructure Development Projects.

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