We are all aware of the importance of estimation in any civil engineering work. The builder needs to have knowledge of the amount of work and the associated costs before taking up any project. It is also important to know how to estimate all the items involved in the project.
This article lists out the general items involved in the estimation of a building.
1. Clearing the Site
Materials on the top of the soil, such as vegetation, bushes, and/or other perishables and organic materials, should be cleared and measured in square meters.
2. Soil Excavation for Foundation Trenches
The earth is excavated for foundation trenches to the exact width and height of the foundation. The sides and the bottom of these trenches are leveled both longitudinally and transversely. Its unit is cubic meters.
3. Earthwork in Filling
This includes filling up the excavated part up to the required depth, either with the soil excavated from the site or soil carried from outside the site. The filling is based on the quality and type of soil that is excavated. Its unit is cubic meters.
Earthwork in filling can be subdivided into:
- Filling in foundation
- Plinth filling: The depth of filling is from the ground level up to the floor level
4. Damp-Proof Course (DPC)
This is generally a layer of 1:2:4 cement concrete mixture mixed with a water-proofing compound laid between the plinth and superstructure walls to prevent the seepage of water rising from the ground through capillary action. It is measured in terms of square meter.
5. Plain Cement Concrete (PCC) Works
In this, one needs to calculate the quantity of PCC required for foundation, trenches, grade slabs, sills, etc. If the slope is provided for the foundations, its quantity needs to be determined. Its unit is cubic meters.
6. Reinforced Cement Concrete Works
The concrete in foundations, grade slab, plinth beams, floor beams, lintel beams, columns, and slabs are all included in the quantities of RCC. This item also includes the concrete in Chajja. No need to deduct the volume of reinforcement from the total volume of concrete. As a separate item, the reinforcement quantity will be determined.
Shuttering of formwork is recommended to be calculated separately. If reinforcement or shuttering are included and considered as a consolidated item with RCC, this should be properly described in the item description. Its unit is cubic meters.
7. Steel Work
The quantity includes bending and binding in position and is measured in quintal. No separate payment for the binding wire is required. For calculation purposes, the quantity of steel is calculated from the percentage volume of reinforced concrete. But for practical purposes, reinforcement is calculated from the bar bending schedule and paid after measuring the bars before concreting.
8. Shuttering (Formwork)
The cost of formwork is approximately 30% of cement concrete. It is measured in square meters, multiplying length and breadth. The measurement is taken as the actual surface in concrete with concrete or any other material requiring formwork. General practice is to consider the area of built-up concrete members.
9. Masonry work
The volume of brickwork is calculated by multiplying the length, breadth, and height of the wall. Its unit is cubic meters. It is convenient to break masonry work into:
- In foundation: Since there are no openings in the wall up to the plinth, no deduction is required in the volume.
- In superstructure wall: The volume of brickwork is first calculated assuming that there are no openings. After calculating the volume of brickwork, standard deductions for volumes of openings, volumes of lintel, etc. are made as prescribed in the building standards.
10. Plastering Work
The measurement is taken as the surface area of the wall before plastering. The required deduction for door and window opening is thereby calculated. Plastering quantity for the ceiling is measured as the area between walls. Soffits of stairs are also considered as ceiling plastering. Certain points to note regarding deductions for openings are as follows:
- Openings not exceeding 0.5 sq.m, no deduction or addition shall be made.
- In case of openings exceeding 0.5 sq.m but not exceeding 3 sq.m and when both the faces of the wall are plastered with the same plaster, the deduction has to be made on only one face.
- For openings of the area exceeding 3 sq.m, deduction shall be made for each face of the wall plastering.
11. Painting
This item includes quantities measured for applying 2-3 coats of whitewash or color wash or emulsion paints. Like in the case of plastering, the quantity for painting is also calculated as area.
12. Flooring and Tiling
This item consists of two sections:
- The flooring of the ground floor: In this, we measure the quantity of rubble soling provided below the foundations, floors, pavement, ramps, etc. The quantity includes either the quantity of thick lime concrete or cement concrete over soling. Then the top part of the flooring is calculated. This top flooring may be of different types, embedded in cement mortar bed. All these items together will contribute to flooring on the ground floor.
- The flooring of top floors: The quantity of flooring is measured as the area between walls that should be floored.
13. Woodwork for Doors and Windows
This item consists of two sections:
- Door and window frame: By multiplying the total length of the frame to its cross-section, the quantity for the door and window frame can be determined. The total length would be two times the height and one width of the opening, as there is no bottom sill. The window frame quantity would include two vertical lengths and two horizontal widths. Its unit is cubic meters.
- Door and window shutters: By multiplying the height by the breadth and stating the thickness in the description, the quantity for the door and window shutters can be determined. For double shutters, the overlapping at the center in between is not accounted for. Other fittings are usually paid individually and provided as separate items. Its unit is square meters.
The estimation calculation should include all these items. It is important to calculate all these quantities to great precision.
Read More
Cost Estimation of Construction Projects
How to Make Deductions in Masonry Construction Estimation?
Methods of Cost Estimation in Projects – Tools and Techniques