Quantity surveying is a vital profession within the construction industry, focusing on the meticulous management of project costs and budgets. From initial design to project completion, quantity surveyors ensure financial viability and efficiency. This guide delves into the core aspects of Quantity Surveying: Measurement and Cost Estimation, providing students with a comprehensive overview of essential concepts and procedures. It's a foundational understanding for anyone embarking on a career in construction finance and project management.
Measurement in quantity surveying transforms architectural drawings into detailed descriptions and quantifiable items. This process is crucial for producing the Bill of Quantities (BoQ), which is then used for tendering, costing, and effective project management. Accurate measurement and cost estimation are paramount for successful project delivery.
Understanding Quantity Surveying: Roles and Documents**What is Quantity Surveying?**Quantity surveying is a profession dedicated to managing construction costs and budgets throughout a project's lifecycle. It begins the moment a plan is drawn and continues until the construction is complete, ensuring financial discipline and accuracy.A quantity surveyor is a professional expert in construction costs and contracts. They apply their knowledge to various duties, whether working for the client or the contractor. Their role is central to the financial health of any construction endeavor.
Key Documents in Quantity Surveying
Several documents are fundamental to the quantity surveying process: - Bill of Quantities (BoQ): A detailed document itemizing materials, labor, and services required for a construction project, used primarily for tendering. - Interim Payment Certificate: Issued by the architect, this certificate indicates the amount due to the contractor for work completed up to a certain stage. - Final Account Certificate: Issued at the end of the defects liability period, releasing all remaining funds, including retention money, to the contractor. - Specification: Detailed requirements for materials, workmanship, and construction methods. - Condition of Contract: Outlines the legal terms and responsibilities between parties. - Contract Drawings: Graphical documents providing side, top, and sectional views of the construction work. - Standard System of Measuring Building Work (SSM): A guide with uniform rules for preparing the bill of quantities.
The Standard System of Measuring Building Work
The Standard System of Measuring Building Work (SSM) is an indispensable guide for quantity surveyors. Issued by the Association of South African Quantity Surveyors in conjunction with the Building Industries Federation, it provides uniform rules for preparing a bill of quantities.
This book is a mandatory reference in any quantity surveyor's office and for every student in quantity surveying. Its primary function is to standardize the preparation of the bill of quantities, ensuring consistency and clarity across all projects.
Types of Building Contracts
Understanding different contract types is crucial for quantity surveyors. These contracts dictate how payment and responsibilities are structured: - Lump-sum contracts: A single fixed price for the entire project. - Labour-only contracts: The contractor provides only labor, with materials supplied by the client. - Cost-plus contracts: The client pays for all actual costs incurred, plus an agreed-upon percentage or fixed fee for profit. - Bill of quantities contracts: Payment is based on the measured quantities of work completed, priced according to the BoQ.
The Bill of Quantities (Bo
Q) DocumentA Bill of Quantities (BoQ) is a critical document in the tendering process for construction projects. It itemizes all materials, labor, and services, detailing terms and conditions, and allowing sub-contractors to price their work accurately.
Relationships of the Bill of Quantities
The BoQ interacts with several key stakeholders in a construction project: - The client (employer) - The architect - The quantity surveyor - The contractor's estimating and costing clerks - The contractor's foreman - The clerk of worksEach relationship highlights the document's central role in communication and financial management.
Procedure for Preparing the Bill of Quantities
The preparation of a BoQ follows a strict chronological order to ensure accuracy and completeness: 1. Study Drawings and Specifications: Thoroughly review all drawings and specifications, then begin the 'taking off' process. 2. Check Side Casts, Squaring, and Checking: Verify preliminary calculations and initial quantity measurements. 3. Abstracting Items and Checking the Abstract: Group similar measured items together and ensure accuracy. 4. Work Up the Abstract, Billing, and Checking the Bill: Further consolidate items and transfer them to the bill paper, then review. 5. Type and Read Over the Bill of Quantities: Finalize the document, ensuring no errors before distribution.
Office Procedures for Quantity Surveyors
Quantity surveyors perform a range of crucial office duties to produce the bill of quantities. These procedures ensure all aspects of a project are accurately measured and accounted for.
Initial Steps: Drawings and Query Lists- Receipt of Drawings: Drawings are often delivered over time, so each is date-stamped and recorded in a register to prevent oversight. - Preparation of Drawings: Before measuring, the quantity surveyor must: - Peruse drawings to understand the building's nature, construction type, and finishes. - Check dimensions, filling in any missing overall dimensions needed for 'take-off'. - Check drawings for any errors.A query list is then compiled for uncertain items or discrepancies found in the drawings or specifications. This list is submitted to the architect for clarification, and all solutions are meticulously recorded as evidence.
Measurement Preparations and Techniques- Cover Page: A set of dimensions must include a title page with project details (building type, location, client, architect, quantity surveyor, and measurement commencement date). - Measuring List: Before 'take-off', a list of all items to be measured is compiled, serving as a reminder and guide. - Collection: These are preparatory side casts done before 'take-off', identified with headings for clarity. Collections are thoroughly checked to prevent errors from being carried forward. - Descriptions: Each dimension requires a clear, concise, and unambiguous description. While abbreviations are used during 'take-off' for efficiency, full descriptions are required for 'working up' and 'billing'. Descriptions must follow standard system information, clearly stating work type, construction details, and relevant sizes.
Taking Off: Essential Considerations
When taking off quantities, several points must be considered for accuracy: - Reference all dimensions clearly. - Make necessary notes on both dimension paper and the plan. - Query unclear construction details or materials. - Coloring in Plans: Use colored pencils to mark measured items on drawings (e.g., red for brickwork, brown for timber) to prevent over-measurement. Plain openings, doors, and windows are not colored. - Always use indicated dimensions; avoid scaling unless absolutely necessary. - Use headings and sub-headings (e.g., floors, openings). - Be accurate, systematic, and methodical. - Number all dimension columns. - Book dimensions in meters; side casts and waste calculations in millimeters.
Principles and Techniques of Measurement
Accurate measurement is the cornerstone of quantity surveying, translating visual plans into quantifiable data.
Forms of Dimensioning
Understanding how dimensions are booked is essential: - Cubic: For items like concrete or excavations (e.g., 25.00 x 0.60 x 0.80 for volume). - Square or Superficial (Super): For items like walls, plaster, or screed (e.g., 13.56 x 2.45 for area). - Linear: For items such as skirting or pipes (e.g., 3.00 for length). - Enumerated: For discrete items like doors, windows, or hinges (e.g., 4 for a count of four items). - Itemized: For items that cannot be given a standard unit of measurement; denoted by 'item' in the dimension column.
Dimension Paper and Its Columns
Dimension paper is specially ruled for entering dimensions and descriptions: - Column A (Timesing Column): Used to multiply single or grouped dimensions. - Column B (Dimension Column): Records lengths, areas, or volumes, rounded to two decimal places. - Column C (Squaring Column): Displays the calculated product of dimensions. - Column D (Description Column): Provides full descriptions of measured items, including references and side casts.
Recording and Referencing Dimensions- Numbering: All dimension sheets are numbered promptly to prevent loss. - Rounding: Dimensions are rounded to two decimal places. - Order of Dimensioning: Follows a sequence: horizontal at right angle to line of sight, horizontal parallel to line of sight, then vertical. - Spacing: Measurements and descriptions must be clearly spaced to avoid crowding. - Bracketing Descriptions: Links dimensions to one or more descriptions, with total squares transferred to abstract paper. - Timesing: Used when identical items occur multiple times. - Dotting On: Gathers similar items from different locations. - Deductions (Omissions) and Additions: Ddt (Deduct) precedes items to be subtracted; Add precedes the first addition item after a deduction. - Adding On: Brackets together different items with the same quantity related to a specific section. - Alterations: Incorrect dimensions are neatly crossed out, marked 'NIL', and correct dimensions booked below; never erased. - Sign-posting (Referencing): Clear references indicate the source of information or location of measured items (e.g., 'Laundry', 'Dining room'). - Side Casts: Reference calculations in the description column, indicating how measurements were established, given in millimeters and to three decimal places.
Methods of Taking Off- Trade-by-trade method: Each quantity surveyor measures a complete trade (e.g., masonry, carpentry) for the entire project, streamlining the process by removing the abstract stage. - Group method: Measurement is divided among surveyors by building sections (e.g., substructure, external walls, roof). This requires careful coordination to avoid omissions or double measurement.
Working Up: From Measurements to Bill
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