Quantity Surveying Notes

Quantity Surveying for Construction Works

  • General Overview

    • Quantity Surveying (Q.S) concerns the estimation and costing in the construction industry.
    • It encompasses various methods of estimating quantities for construction elements like buildings and infrastructure.

  • Major Aspects Covered

    • Units of Measurements
    • Requirements of Estimation and Costing
    • Methods of Taking Out Quantities
    • Estimating of Buildings

Classification of Trades of Work

  1. Fill and Excavations: أعمال الحفريات والطمم
  2. Concrete Works: أعمال الخرسانة
  3. Masonry Works: أعمال الحجر
  4. Block Works: أعمال الطوب
  5. Plastering: أعمال القصارة
  6. Tile and Marble Works: أعمال البالط والرخام
  7. Joinery: أعمال المنجور
  8. Glazing and Aluminum/Steel Works: أعمال الحديد واألمنيوم والزجاج
  9. Painting: أعمال الدهان
  10. Plumbing Installations: أعمال التمديدات الصحية
  11. Central Heating and Air-Conditioning: أعمال التدفئة المركزية والتكييف
  12. Electrical Installations: أعمال التمديدات الكهربائية
  13. Waterproofing – Roof: أعمال عزل السطوح
  14. External Works: الأعمال الخارجية

Units of Measurements

  • Types:

    1. Linear Measurements (Length): Measured in meters (m), centimeters (cm), etc.
    2. Areal Surface Measurements (Area): Measured in square meters (m²), square feet (ft²), etc.
    3. Cubical Measurements (Volume): Measured in cubic meters (m³).
    4. Unit-works: Counted as numbers (e.g. doors, windows).

  • Measurement Rules:

    1. Measurements should be for finished items.
    2. Same type of work under different conditions measured separately.
    3. All measurements shall be subjected to acceptable tolerances:
    • Linear: closest to 0.01 m
    • Area: closest to 0.01 m²
    • Volume: closest to 0.01 m³

Importance of Estimation and Costing

  • Necessity:
    1. Clarifies intended work scope; feasibility can be assessed.
    2. Determines timeframe for completion.
    3. Essential for obtaining quotations and arranging contracts.
    4. Aids in planning project funding and controlling expenditures.

Data Required to Prepare an Estimate

  • Essentials:
    1. Drawings: Detailed plans including structural and architectural.
    2. Specifications: General descriptions and detailed specifics regarding materials and techniques.
    3. Rates: Local market rates for materials, labor, and transportation.
    4. Completed Works: Regular measurements of work completed for accurate billing.

Procedure of Estimating

  • Steps:
    1. Detailed estimation of quantities for construction elements.
    2. Calculation of rates using estimated quantities and market rates.
    3. Preparing an abstract of estimates to summarize costs for different work units and overall project.

Basic Rules of Calculations

  • Quantities can be specified using various techniques:
    1. Quantity = Number of Units (e.g. Quantity for window type B2 = 12 units).
    2. Quantity = Mass/Weight (e.g. Quantity for white cement = 20 kg).
    3. Quantity = Length (e.g. Quantity for external stairs handrail = 16 m).
    4. Quantity = Area (e.g. Quantity for mosaic tiling = 40 m²).
    5. Quantity = Volume (e.g. Quantity for Plain Cement Concrete PCC = 120 m³).

Methods of Taking Out Quantities

  • Categories:
    1. Long Wall – Short Wall Method
    2. Centre Line Method
    3. Mixed Method (Centre Line and Short Wall)
  • Applicable for: General works including earthwork and brickwork.

Example of Long Wall – Short Wall Method

  • Steps:
    • Identify long and short walls and calculate respective lengths and quantities.
    • e.g. Length of Long-Wall = Length of center line + Breadth of wall.

Detailed Estimate of Cost

  • Essential to calculate accurate quantities, identify rates, and determine overall costs based on planned works and possible unforeseen expenses.
  • Calculating Overall Cost:
    • Target known costs, quantities, and utilize formulas to express relationships accurately.

UK Methods of Measurements and Quantity Surveying

  • Various standard codes and methods exist:
    1. Standard Methods of Measurement of Building Works (SMM7)
    2. Civil Engineering Standard Method of Measurement (CESMM3)
    3. RICS Code of Measurement Practice.