Quantitative estimating techniques

Quantitative Estimating Techniques

• Introductory Concepts
  • Quantitative estimating: This is a method used in construction to determine the total cost of a project by calculating and totalling all the costs associated with different resources needed for the project like materials, labour and equipment.
  • Purpose: The main purpose of quantitative estimating techniques is to predict the likely cost of an upcoming project in as much detail as possible.
  • Unit pricing: Involves estimating the cost of individual units of work, and multiplying them by the quantity required for the project.
• Common Quantitative Estimating Techniques
  • Take-off Quantities: This technique involves measuring the quantities of materials from drawings or plans and then estimating the cost based on these measurements.
  • Analogous Estimating: This involves using actual cost of previous, similar projects as the basis for estimating cost of the current project.
  • Detailed Estimating: This involves estimating the cost of each individual activity in a construction project, and is usually used when the project scope, schedules and tasks are predefined.
  • Parametric Estimating: Involves using statistical relationships between historical data and variables to calculate an estimate.
• Principles in Quantitative Estimating
  • Accuracy: Estimates should be as accurate as possible. Ensure to cross-check measurements and calculations, and account for all possible costs.
  • Comprehensiveness: All aspects of the project should be considered, including labour, materials, equipment, utilities, permits, and contingencies for unforeseen costs.
  • Consistency: The same unit measurements and pricing methods should be used throughout the estimation process.
  • Transparency: Maintain clear and detailed records of how estimates were measured and calculated to allow for easy review and auditing.
• Potential Issues in Quantitative Estimating
  • Inflation: Fluctuations in the cost of labour and materials can cause the actual costs to differ from the estimate.
  • Unforeseen costs: Potential complications and unexpected issues may arise during the construction process that were not considered in the estimate.
  • Measurement errors: Incorrect measurements can lead to inaccuracies in estimates. Careful consideration should be given to reduce these errors.
• The Role of Estimators
  • Estimator’s job: The role of an estimator in construction is to gather and analyse data in order to estimate the time, money, materials and labour required for a project.
  • Site visits: Before making an estimate, it’s often necessary for the estimator to conduct a site visit to understand the potential challenges and complications of the project.
  • Communication: Estimators need to communicate effectively with engineers, architects, owners, contractors and sub-contractors to gather all necessary information and ensure alignment of the project’s goals.