Purpose and importance of specification

A specification is a written description of the quality of materials, standard of workmanship, method of construction and mode of measurement and payment for each item of work in a project. Together with drawings and the bill of quantities, it forms the contract document.

Purpose

1. To describe the quality and quantity of materials, such as grade of cement, size of aggregate, mix ratio.
2. To define the method and standard of workmanship for each work item.
3. To guide the contractor on how the work must be done, and the engineer on how to inspect it.
4. To serve as the basis of the rate analysis, estimate and tender.
5. To fix the method of measurement and payment.
6. To control quality by giving tests and tolerances.

Importance in construction contracts

• Basis of the contract: it makes clear what the contractor has to supply, so tenders are comparable and fair.
• Quality assurance: work and materials below the specification can be rejected.
• Avoids disputes: the written standard settles disagreements between owner, engineer and contractor.
• Cost estimating: the contractor can price the work correctly; the owner can check the estimate.
• Supervision tool: the engineer inspects and approves against the specification.
• Uniformity: the same standard is followed by different contractors and work items.
• Legal document: it is used in claims, variations and arbitration.
• Safety and durability: it ensures the structure performs as designed.
• Basis for measurement and payment, which prevents overpayment.