UNIT 2: QUANTITY SURVEYING & COSTING (CE-503 C)

I. FUNDAMENTALS OF ESTIMATION

Purpose and Importance of Estimation

• Purpose: To determine the probable cost of a construction project before commencement. It is the foundation for financial planning, budget control, and decision-making.

• Importance:

  • Financial Planning: Secures funds, arranges loans, and assesses financial viability.

  • Tender & Contracting: Forms the basis for inviting tenders and entering into contracts.

  • Cost Control: Provides a benchmark (estimated cost) against which actual expenditures are measured.

  • Decision Making: Helps in choosing between alternative designs, materials, or methods.

  • Valuation: Essential for property valuation, insurance, and sale/purchase.

Types of Estimates

Principle of Units for Various Items

• Length (m, km): Masonry (walls, columns), plastering, painting, pipes, cables.

• Area (sq. m): Flooring, roofing, plastering, painting, damp proof course (DPC), glass, shutters.

• Volume (cu. m): Earthwork, concrete, brickwork, lime concrete, plastering (thickness considered).

• Number (each): Doors, windows, fittings, fixtures, manholes, gullies.

• Weight (tonne, quintal): Steel reinforcement, ironwork, bitumen.

• Running Meter (rm): Pipes, cables, conduits (length with fixed cross-section).

[!TIP] Exam Focus: Distinguish between Supplementary (new work) and Revised (excess in original work) estimates. Know the unit for each common item (e.g., plastering is sq.m but calculated from wall dimensions in m).

II. DETAILED ESTIMATE PREPARATION

Data Required

1. Detailed Drawings: Plans, sections, elevations, foundation details.

2. Specifications: Quality of materials, workmanship standards.

3. Rates: From Current Schedule of Rates (CSR) or market analysis.

4. Standard Data: Material constants (e.g., cement bags/cu.m concrete), wastage percentages.

5. Bye-laws & Standards: Local building bylaws, IS codes.

Procedure (Step-by-Step)

1. Study Drawings & Specifications: Understand scope, dimensions, materials.

2. Take-off Quantities: Measure dimensions from drawings for each item (e.g., wall length, height, thickness for brickwork).

3. Apply Deduction Rules: For openings, embedded items, etc. (See rules below).

4. Abstract Preparation: Transfer item-wise quantities to an Abstract Sheet with columns for Item No., Description, Quantity, Rate, Amount.

5. Rate Analysis: Prepare or adopt rates for each item (covered in Section V).

6. Total Cost Calculation: Sum of all Amount columns. Add contingencies, supervision charges, etc.

7. Report Preparation: Compile estimate, drawings, and reports into a Detailed Project Report (DPR).

Factors to be Considered

• Site Conditions: Accessibility, water availability, soil type.

• Material & Labor Availability: Local sources, seasonal fluctuations.

• Transportation & Handling: Cost of moving materials to site.

• Wastage & Overheads: Include for materials (2-5%) and site/office overheads (2-5%).

• Contingencies: Unforeseen items (usually 2-5% of total cost).

• Profit of Contractor: Typically 10% of total cost.

• Taxes & Levies: GST, cess, etc.

Rules for Deduction in Masonry & Plastering

[!TIP] Common Pitfall: Students often forget to apply the 100 mm rule for beams/columns in masonry. Always check the width. Also, remember plastering deductions are based on area of opening, not volume.

III. APPROXIMATE ESTIMATES

Rough Estimate (Cubical Content Method)

1. Calculate Plinth Area (PA): PA = (Length x Breadth) x No. of floors.

2. Calculate Total Cubical Content (TCC): TCC = PA x Total Height of building (from foundation to top of parapet).

3. Structural Cost: Structural Cost = TCC x Rate per cu. m (Rate based on locality & type of construction).

4. Add Ancillary Costs (as % of Structural Cost):

   • Water supply & Sanitary: 5-8%

   • Electrification: 6-8%

   • Contingencies: 2-3%

   • Supervisor charges: 2-3%

   • Fluctuation of rates: 5%

   • Contractor's profit: 10%

5. Total Estimated Cost: Total = Structural Cost + Sum of all Ancillary Costs.

Example from Past Paper (Jun 2025):

Given: PA = 500 m²/floor, Ht/storey = 3.5 m, G+2 = 3 floors.

TCC = 500 x (3 x 3.5) = 500 x 10.5 = 5250 m³.

Structural Cost = 5250 x 1000 = Rs. 52,50,000.

Ancillary % sum = 8+6+5+10+3 = 32%.

Ancillary Cost = 32% of 52,50,000 = Rs. 16,80,000.

\boxed{\text{Total Estimated Cost} = 52,50,000 + 16,80,000 = \text{Rs. 69,30,000}}

Abstract Estimate vs. Detailed Estimate

Approximate Estimate from Plinth Area Rate

• Calculation: Total Cost = Plinth Area (sq.m) x Plinth Area Rate (Rs./sq.m).

• Plinth Area Rate: Includes cost of construction up to plinth level only (foundation, plinth, superstructure up to window sill level). It does NOT include finishing (flooring, plastering, painting, electrification, etc.).

• Inclusion of Ancillary Costs: Costs for electrification, water supply, contingencies, supervisor charges are added as percentages of the cost of building (up to plinth) or sometimes of the total plinth area cost. The exact base (structural cost vs. total) must be specified in the question.

• Example (Dec 2024):

  • Plinth Area = 180 sq.m, Rate = Rs. 3500/sq.m.

  • Cost of Building (up to plinth) = 180 x 3500 = Rs. 6,30,000.

  • Add: Special Arch. (1%) = 6,300; Electrification (8%) = 50,400; W.S. (5%) = 31,500; Contingencies (3%) = 18,900; Supervisor (3%) = 18,900.

  • Total Estimated Cost = 6,30,000 + (1+8+5+3+3)% of 6,30,000 = 6,30,000 + 20% of 6,30,000 = 6,30,000 + 1,26,000 = Rs. 7,56,000.

IV. ESTIMATION METHODS FOR SPECIFIC WORKS

A. Building Estimation

Long Wall and Short Wall Method

• Procedure:

  1. Identify long walls (outer walls running along the length of the building) and short walls (walls along the breadth).

  2. Length of Long Wall (at a level) = Center to Center length of building + (Full thickness of wall).

  3. Length of Short Wall (at a level) = Center to Center breadth of building - (Full thickness of wall).

  4. For Foundation & Plinth: Use center line lengths (as above).

  5. For Superstructure (above plinth): Deduct half thickness of the wall from the center line length for each successive lift.

• Example: For a room 10m x 8m C-C with 230mm thick walls:

  • Long Wall (foundation) = 10 + 0.23 = 10.23 m.

  • Short Wall (foundation) = 8 - 0.23 = 7.77 m.

  • Long Wall (superstructure) = 10.23 - (0.23/2) = 10.115 m (for each lift above plinth).

Brickwork & Plastering Estimation

• Brickwork Quantity: Volume = Length x Height x Thickness (use correct wall length from above method).

• Plastering Quantity: Area = (Perimeter of wall x Height) - Area of openings. For both sides, multiply by 2.

• Cost: Cost = Quantity x Rate per cu.m (for brickwork) or per sq.m (for plastering).

B. Earthwork Estimation

Mid-Sectional Area Method (for roads, embankments)

• Formula for Volume between two sections:

$$V = \frac{A_1 + A_2}{2} \times L$$

where,

$$\displaystyle A_1, A_2 $$ = Cross-sectional areas at two chainages (in sq.m),

$L$ = Distance between sections (in m).

• Cross-Sectional Area Calculation (for embankment with side slope m:1):

$$A = \left( B + mH \right) H$$

where,

$B$ = Top width (m),

$H$ = Depth of embankment/cutting (m),

$m$ = Slope ratio (horizontal:vertical).

• Example (Jun 2025): Embankment L=500m, B=4m, H=2m, slope 1.5:1 (m=1.5).

  $$\displaystyle A = (4 + 1.5 \times 2) \times 2 = (4+3) \times 2 = 14 \text{ sq.m} $$.

  Assuming uniform section, $$\displaystyle V = A \times L = 14 \times 500 = \boxed{7000 \text{ cu.m}} $$.

Mean Sectional Area Method

• Used when many cross-sections are taken at regular intervals.

$$\text{Total Volume} = \frac{L}{n} \times \left( A_1 + 2A_2 + 2A_3 + ... + 2A_{n-1} + A_n \right)$$

where $L$ = total length, $n$ = number of sections.

C. Concrete, RCC, and Masonry Estimation

Material Statement for Concrete (per 1 cu.m)

• Note: Actual quantities include wastage (usually 2-5% for sand/aggregate). Cement bags = 50 kg each.

• Calculation for 25 cu.m RCC 1:2:4:

  Cement = 6.4 bags/cu.m x 25 cu.m = 160 bags.

  Sand = 0.42 cu.m/cu.m x 25 = 10.5 cu.m.

  Aggregate = 0.84 cu.m/cu.m x 25 = 21 cu.m.

Brickwork Estimation (1st Class)

• Volume: L x H x T (use long/short wall method).

• Mortar Ratio: Common ratios are 1:4 (foundation/plinth) and 1:6 (superstructure). Affects rate analysis, not quantity of bricks (which is based on net volume).

• No. of Bricks/cu.m: ~500 (for standard brick 190x90x90 mm with 10mm mortar).

Plastering Estimation

• Area: (Perimeter x Height) - Deductions (see rules).

• Thickness: Usually 12mm (internal), 20mm (external). Affects volume of mortar but cost is per sq.m.

• Mortar: Typically 1:4 or 1:6 for 12-20mm thickness.

Damp Proof Course (DPC)

• Material: Cement concrete (1:2:4) or bitumen felt.

• Thickness: 25-40 mm for concrete DPC.

• Quantity: Area = Length of wall x Thickness of DPC (usually calculated in sq.m).

Lime Concrete (Foundation)

• Mix: Common is 1:2:6 (Lime : Surkhi : Brick Ballast 40mm down).

• Quantity: Volume in cu.m. Rate analysis requires material breakdown (lime, surkhi, ballast).

D. Specialized Works

Culvert Construction

• Methods: Pre-cast RCC segments, cast-in-situ, pipe culverts (RCC, Hume pipes).

• Estimation Items: Earthwork, foundation, base slab, walls, top slab, pitching, approaches, inlet/outlet structures.

• Key: Consider hydraulic design, scour depth, soil bearing capacity.

Cost Estimates for Drainage & Electrification

• Drainage: Excavation, bed concrete, masonry walls, slab, covers, connections. Quantities in m (pipes), cu.m (structures), sq.m (covers).

• Electrification: Conduiting, wiring, switches, sockets, fixtures, MCBs, main board. Quantities in rm (wires/conduits), each (fixtures/switches). Rates are highly item-specific.

V. RATE ANALYSIS

Definition & Purpose

• Definition: Systematic determination of the unit rate (Rs./unit) for a specific item of work (e.g., Rs./cu.m for concrete, Rs./sq.m for plastering).

• Purpose: To find the fair and reasonable cost of an item, including all direct and indirect expenses, for preparing a detailed estimate or for payment certification.

Factors Affecting Rate Analysis

1. Material Costs: Cost of cement, sand, aggregate, bricks, steel, etc. + wastage (2-5%).

2. Labor Costs: Skilled/unskilled labor wages (daily or task-based). Include task work (piece-rate) factors.

3. Equipment & Tools: Depreciation, hire charges, fuel for mixers, pumps, etc.

4. Overhead Charges: Site establishment, office expenses, supervision, insurance, taxes (not GST on materials).

5. Contractor's Profit: Typically 10% of total cost (material+labour+equipment+overheads).

6. Fluctuation of Rates: For long-duration projects, include a percentage (e.g., 5%) for material/labor rate hikes.

7. Water & Incidentals: Water for curing, sundries, small tools.

Preparation of Rate Analysis (Example: Lime Concrete 1:2:6)

Overhead Charges

• Components: Site rent, office staff salary, electricity, water, telephone, stationery, insurance, local taxes, security.

• Inclusion: Added as a percentage (usually 2-5%) of the Subtotal (Material+Labour+Equipment) before adding profit.

• Formula: Total Rate/cu.m = (Direct Cost + Overheads) + Profit.

VI. VALUATION OF BUILDINGS

Purpose of Valuation

• To determine the market value or fair value of a property for:

  • Sale/Purchase, Mortgage, Insurance.

  • Rent fixation, Taxation (property tax).

  • Compulsory acquisition (government), Partition of property.

  • Financial reporting (book value).

Methods of Valuation

Key Valuation Terms

• Sinking Fund: Fund accumulated periodically to replace/renew a property after its useful life. It is the amount set aside each year so that with compound interest, the total equals the replacement cost at the end of life.

  • Determination: Annual Sinking Fund = \frac{R}{(1+i)^n - 1} \times i, where R = Replacement Cost, i = interest rate, n = life.

  • Importance: Ensures funds are available for future replacement without sudden burden.

• Year’s Purchase (Y.P.): The present worth of Re. 1 payable annually for a fixed number of years at a given rate of interest. It is the reciprocal of the Annuity Factor.

  • Calculation: Y.P. = \frac{1}{i} \left[ \frac{1 - \frac{1}{(1+i)^n}}{1} \right] (for standard rate tables).

  • Example (Nov 2023): Life=15 yrs, Interest=7% for capital, 4% for sinking fund. Use combined rate or calculate separately. Typically, Y.P. for 15 yrs at 7% = 9.12 (from tables).

• Dual Rate Interest: Using two different interest rates: one for capital recovery (return on investment) and one for sinking fund (replacement). The capitalization rate is derived from both.

• Scrap Value vs. Salvage Value:

  • Scrap Value: Value of dismantled materials at the end of useful life (very low, often negligible).

  • Salvage Value: Value of the entire property if sold as a going concern at the end of its economic life (higher than scrap).

• Market Value vs. Book Value:

  • Market Value: Current open market price (fluctuates).

  • Book Value: Original cost - Accumulated depreciation (accounting term, fixed in books).

• Value, Cost, Price:

  • Value: Worth of property (subjective, utility-based).

  • Cost: Amount spent to construct/acquire (historical).

  • Price: Amount actually paid/asked in a transaction (market-driven).

Functions of a Valuer

• To determine fair value for various purposes.

• To prepare valuation reports and certificates.

• To advise on investment, rent fixation, insurance.

• To act as an expert witness in legal disputes.

• To assess depreciation and obsolescence.

VII. FINANCIAL AND ADMINISTRATIVE ASPECTS

Fixation of Standard Rent

• Method (as per Rent Control Acts): Based on Cost Method.

  • Annual Rent = (Cost of Construction - Depreciation) x Fair Rate of Return + Land Value x Rate.

  • Or simpler: Standard Rent = \frac{Total Cost (including land)}{100} \times \frac{9}{2} (old formula, varies by state).

• Key: Ensures landlord gets reasonable return on investment while protecting tenant.

Current Schedule of Rates (CSR)

• Meaning: Official publication (by PWD, CPWD, etc.) listing standard rates for various items of work at a given place and time.

• Preparation: Based on analysis of material, labor, equipment costs, overheads, and profit in that region. Updated periodically.

• Usage: Basis for preparing estimates, analyzing rates, settling measurements, and paying contractors in government projects.

Detailed Project Report (DPR)

• Content:

  1. Executive Summary.

  2. Project Background & Objectives.

  3. Location & Site Details.

  4. Technical Feasibility (Design, Drawings, Estimates).

  5. Financial Feasibility (Cost Estimates, Funding, Economic Analysis).

  6. Implementation Schedule (Bar Chart/PERT).

  7. Organizational Setup.

  8. Risk Analysis & Mitigation.

  9. Conclusions & Recommendations.

• Preparation Steps: Data collection → feasibility studies → design → cost estimation → financial planning → compilation.

Tender Process

• Tender Notice: Advertisement inviting bids. Contains: project name, scope, cost, earnest money, completion time, last date, address.

• Bidding: Contractors submit tender documents (BOQ, rates, terms).

• Award: Lowest (L1) or most advantageous bid is accepted after technical & financial evaluation. Letter of Award (LoA) issued.

Bill of Quantities (BOQ) and Abstract Sheet

• BOQ: Itemized list of all quantities of work from detailed estimate, with blank columns for unit rate and amount to be filled by tenderer.

• Abstract Sheet: Summary of BOQ, grouping items into trades (earthwork, concrete, masonry, etc.) showing total quantities and total estimated cost per trade. Used for quick reference and payment.

Work Charge Establishment

• Definition: Dedicated technical & administrative staff (engineers, clerks, assistants) deployed at the project site for supervision and management.

• Components: Salaries, allowances, transport, office expenses at site. Charged to the project as site overheads.

Gross Income vs. Net Income

• Gross Income: Total revenue from rent/sales before any deductions.

• Net Income: Gross Income - Outgoings (taxes, repairs, insurance, management charges). This is the actual return to the owner.

Petty Supervision and Contingencies

• Petty Supervision: Charges for site supervision by junior staff (overseers, clerks). Usually a small fixed percentage (1-3%) of the total cost.

• Contingencies: Provision for unforeseen items not in the estimate (e.g., minor design changes, price fluctuations). Usually 2-5% of total cost.

VIII. KEY CONSTRUCTION STAGES AND COST PERCENTAGES

Identification of Stages

1. Foundation & Plinth: Earthwork, PCC, foundation concrete, plinth filling, DPC.

2. Superstructure (Lintels, Columns, Beams, Slabs): Brickwork/RCC work for floors, roofs.

3. Finishing: Plastering, flooring, painting, joinery, glazing.

4. Services: Electrification, plumbing, drainage, HVAC.

5. External Works: Compound wall, gates, landscaping, approach roads.

Approximate Cost Percentages (Typical for a Residential Building)

Factors Affecting Cost Percentages

• Location: Material/labor cost variation.

• Design & Specifications: High-rise vs. bungalow, luxury finishes.

• Material Choices: Marble vs. tiles, vitrified vs. ceramic.

• Labor Charges: Regional wage differences.

• Architectural Features: Complex shapes, cantilevers increase superstructure %.

• Service Intensity: Central AC, smart home systems increase services %.

[!TIP] Exam Focus: Be ready to justify why a stage's percentage is high/low. E.g., "Finishing % is high in a hospital due to special flooring and sterile plaster." Also, remember Foundation+Superstructure typically forms ~60-70% of total cost.