Estimation & Costing In ONE SHOT | SSC JE Civil Engineering Classes | Estimation & Costing SSC JE

Summary

The lecture provides a broad revision of estimation, costing, valuation, measurement rules, and related civil-engineering calculations. It moves from foundational definitions to types of estimates, area calculations, measurement units, cost allowances, and selected formulas. The subtitles end while introducing brick soling.

Construction Stages and Key Terms

The instructor describes five construction stages:

1. Planning — initiate and assess the proposal.
2. Pre-construction — survey the site, prepare preliminary budgets, and complete the design and drawings.
3. Procurement — buy or rent equipment and arrange resources.
4. Construction — carry out the building work.
5. Post-construction — complete finishing, measurements, and quality checks.

Key terms:

• Estimation is the probable or approximate cost of a project, calculated before construction using drawings, materials, site location, and manpower.
• Costing is found by multiplying the quantity of work by its suitable rate.
• Valuation is the current fair price of an asset, such as land or a completed building.
• Quantity surveying involves working out quantities for the various work items.

Estimates help determine whether a project is financially feasible, how long it may take, what budget to use when inviting tenders, and how to monitor expenditure. The actual cost can only be tallied after construction is complete.

Information Needed to Prepare an Estimate

The instructor identifies three essential inputs:

• Drawings: May include plans, sections, elevations, dimensions, and site or location information.
• Specifications:
  • General (brief) specifications give a broad idea of the work, its nature, and basic materials or proportions.
  • Detailed specifications describe the work more fully, including quality, quantities, workmanship, and the method of execution.
• Rates: Depend on the cost and availability of materials, labour, and machinery. The lecture distinguishes skilled from unskilled labour and notes that equipment needs also affect cost.

Areas Used in Building Estimates

The instructor distinguishes several area terms:

• Plot area is the site area. It is broadly divided into the building area and the surrounding setback area, which is left around the building for movement and possible future expansion.
• Plinth area is the built-up covered area measured at floor level from the outside face of one external wall to the outside face of another. It can apply to a basement or any storey. Any offset is excluded.
• Built-up area refers to constructed portions of the building, such as rooms and certain balconies or service spaces.
• Super built-up area includes the built-up area plus certain shared or external constructed areas, such as corridors, lobbies, parking, or a swimming pool.
• Floor area is calculated by subtracting wall area from plinth area.
• Carpet area is the usable or lettable area after specified spaces and services are excluded from the floor area.

The lecture gives these approximate planning figures:

• Residential carpet area: about 50–65% of plinth area.
• Non-residential office carpet area: about 60–75% of plinth area.
• Plinth area is generally about 10–20% greater than carpet area.
• Horizontal circulation (movement on the same floor): roughly 7–15% of plinth area, with 10% offered as a useful exam figure.
• Vertical circulation (movement between floors by stairs, lift, ramp, or escalator): roughly 3–5% of plinth area.

The instructor also gives plot-size categories and ground-coverage percentages for different plot sizes. These are lecture figures and should be checked against applicable local rules or exam references.

Plinth-Area Inclusions and Exclusions

Items discussed as generally included in plinth area include:

• Walls, measured at floor level and excluding offsets.
• Sanitary shafts up to 2 m²; larger shafts are excluded.
• AC ducts, garbage chutes, electrical-installation spaces, and water-supply and firefighting pipes.
• Lifts and covered staircases.
• A veranda: 100% of its area if covered and 50% if uncovered.
• A balcony: 100% if protected by a projection above and 50% if unprotected.
• Alcoves, depending on height: 25% for up to 1 m, 50% for 1–2 m, and 100% above 2 m, according to the lecture.

Items described as excluded from plinth area include lofts, architectural bands and cornices, vertical sun-breakers or box louvers, towers and domes, open platforms, spiral staircases, machine rooms, courtyards, cantilevered porches, and backyard areas.

Wall Area and Carpet-Area Details

Wall area may include doors and other openings, intermediate supports, substantial plaster projections, flues or chimneys, fireplaces projecting beyond the wall face, and cupboards within the stated height limit. Certain small projections, such as a stove platform projecting beyond the wall face, are excluded from wall area.

Spaces listed as excluded when calculating carpet area include circulation spaces, verandas and balconies, stairs, shafts, machine rooms, bathrooms and lavatories, kitchens and pantries, stores, canteens, plant rooms, AC ducts, service installations, and lifts.

Types of Estimates and Their Methods

Preliminary or Approximate Estimates

These rough estimates are used early in a project to assess likely cost and financial feasibility. The instructor presents five methods:

• Plinth-area method: Approximate cost = plinth area × plinth-area rate.

• Service-unit method (also called the unit-rate or functional method): Uses a service unit—such as a classroom, hospital bed, hotel room, theatre seat, or kilometre of road—and the cost per unit.

• Cubical-content method: Cubical content = plinth area × building height. Approximate cost is found using the rate per unit of cubical content. The instructor notes that including height can make this method more suitable for multi-storey buildings than the plinth-area method.

• Typical-bay method: Estimates cost using the number of bays or spans and the rate per bay or span, particularly for bridges.

• Approximate-quantity method: Estimates work using wall lengths in running metres, with the structure considered in parts such as foundation/plinth and superstructure.

Detailed Estimate

A detailed estimate is presented as the more accurate and reliable estimate. It involves finding quantities for each item and multiplying them by the corresponding rates.

The process uses two main documents:

• Measurement book/sheet: Records item descriptions, length, breadth, height, and quantity.
• Abstract sheet: Records the calculated amounts based on quantities and rates.

A Bill of Quantities (BOQ) is described as similar to an abstract sheet, with quantity, unit, rate, and amount columns. In the arrangement discussed, the rate and amount columns are left for the contractor to fill in.

Revised and Supplementary Estimates

• A revised estimate is prepared when the cost departs from the original estimate. The lecture gives a 5% deviation from a detailed estimate and a 10% deviation from a preliminary estimate as triggers discussed in class.
• A supplementary estimate is used when additional work is required.
• A revised and supplementary estimate may be needed when materials or designs change and affect cost, or when work is abandoned partway through and the remaining work is less than 95% of the original cost, as explained in the lecture.

Repair and Maintenance Estimates

• Annual repair estimate: Covers routine yearly maintenance and minor repairs, such as whitewashing. The lecture gives an approximate allowance of 1–1.5% of overall cost.
• Quadrennial repair: Repair work carried out every four years, including painting and repairs to damaged plaster, doors, or windows.
• Special repair estimate: Prepared for major or unusual damage, such as earthquake damage, a damaged roof, or broken doors and windows that need replacement.

Lump-Sum Allowances and Project Approvals

The instructor lists example allowances that may be added to an estimate. These are approximate lecture figures, not universal rates:

• Contingencies for unforeseen work: 3–5%.
• Work-charge establishment: 1.5–2%.
• Tools and plant: 1–1.5%.
• Departmental charges for planning, surveying, estimating, drawings, and design: 10–15%.
• Sanitary and water-supply work: 8%.
• Electrification: 8%.
• Fans in public buildings: 4%.
• Drinking-water requirements: 1–1.5%.
• Labour: approximately 25–35%.
• Contractor’s profit: approximately 10%.
• Overheads: approximately 10%.

Three approval or sanction stages are outlined:

1. Administrative sanction: The proposal and preliminary estimate are reviewed for purpose and budget.
2. Expenditure approval/fund allocation: Funds are assigned after administrative approval.
3. Technical sanction: A detailed estimate, specifications, drawings, and rates are submitted to the competent engineering authority.

Measurement Rules, Units, and Deductions

Units of Measurement

• Cubic metres: Bulk earthwork (with the lecture distinguishing shallow excavation), concrete work, thicker brickwork, stonework, and many timber-frame items.
• Square metres: Surface work and thin work, including shallow excavation, DPC, some roof-terracing work, partition brickwork under the stated thickness threshold, honeycomb brickwork, plastering, painting, and many sheet or panel items.
• Running metres: Linear items such as courses, pipes, fencing, joints, and certain trims.
• Numbers or counts: Items such as electrical points and some individual components.
• Kilograms or quintals: Specified materials and metalwork, depending on the item and convention.

The instructor notes that unit selection can depend on the work’s thickness and whether it is measured as bulk or surface work.

Lead and Lift

• Lead is the horizontal distance over which excavated material is transported.
• Lift is the vertical distance over which it is moved.
• The lecture discusses conventional lead and lift values and gives surface factors of 1.0 for a metal road, 1.1 for a stone-and-sand track, and 1.4 for a mud track.
• It also describes converting lift into an equivalent lead using multipliers for different lift ranges. The transcript’s figures in this section are somewhat unclear, so they should be verified against the relevant specification or study material.

Measurement Accuracy and Deductions

The lecture provides precision rules for dimensions, area, volume, steelwork, and timberwork; the stated tolerances vary with the item and dimension.

For openings in plastering, the lecture says:

• No deduction is made for openings below the stated small-area threshold.
• For openings between 0.5 and 3 m², one face is deducted.
• For openings above 3 m², both faces are deducted.

No deduction is made for certain embedded ends of beams or rafters, or for specified small bearings and projections. For an arch opening, the lecture describes calculating the arch’s mean length and accounting for the opening and arch separately.

Steel, Bar Bending, and Soling

Steel weight can be estimated using:

Weight (kg) = d²/162 × length (m)

Here, d is the bar diameter in millimetres.

The Bar Bending Schedule (BBS) is a comprehensive record of bar location, diameter, type and grade, identification mark, length, and bending details.

Crank length is based on straight length plus additional length due to bends and any hooks. The lecture gives approximate bend allowances by angle for one bend:

• 0.27d at 30°
• 0.42d at 45°
• 0.57d at 60°
• 0.89d at 90°

Allowances increase when there are bends on both sides. Hook allowances are also discussed.

Soling is a hard brick or stone layer placed over the soil to improve its bearing capacity. The instructor introduces flat soling and edge soling and begins a brick-count example, but the subtitles cut off before the discussion is completed.

Speakers and Sources Featured

• Shubham Dadheech Sir — the instructor and primary speaker, identified by the video metadata; the subtitles themselves do not clearly state his name.
• Live students/viewers — an unnamed audience appearing through comments and questions. No other clearly identifiable speakers or sources are featured.