Part 1 of 2
Specifications
Last reviewed 16 Sept 2026 · 7 min read
Meaning and purpose
Specifications are written descriptions of the quality of materials, workmanship, method of construction, tests and mode of measurement for each item of work. Drawings show what is to be built (shape, size, location); specifications describe how and with what quality.
Purposes
- Define the quality of materials and workmanship precisely.
- Provide the basis for rate analysis and estimating.
- Enable uniform tendering — all contractors quote for the same work.
- Guide the execution and supervision of work at site.
- Serve as a legal document (part of the contract) for settling disputes.
- Allow checking of work and materials through specified tests.
Types of specifications
| Type | Description |
|---|---|
| General (brief/outline) specifications | Short description of the class of building and main features — type of foundation, walls, roof, flooring, finishing — used with preliminary estimates |
| Detailed specifications | Complete description of each item — materials, proportions, method of preparation and execution, curing, tests, finishing, mode of measurement and payment — used with detailed estimates and contracts |
| Standard specifications | Published by organisations and used as references — e.g. CPWD Specifications, MoRTH Specifications for Road and Bridge Works, state PWD specifications, relevant BIS standards |
| Manufacturer's specifications | Instructions from manufacturers for proprietary products (waterproofing compounds, adhesives, sealants) |
| Open specifications | Allow materials/products meeting stated requirements from any source — encourages competition |
| Closed (proprietary/restricted) specifications | Specify a particular brand/product — used where required, but restrict competition (public works generally require "or equivalent") |
| Performance specifications | Specify required results/performance (e.g. strength, durability, compaction density) — method left to the contractor |
| Prescriptive (method) specifications | Specify materials and methods in detail (e.g. mix proportions, number of roller passes) |
Principles of writing specifications
- Clear, concise and unambiguous language; avoid vague terms ("good quality", "as directed" without limits).
- Consistent with drawings and other contract documents; any conflict to be resolved by stated precedence.
- Follow a logical sequence — materials → preparation → execution → curing/protection → tests → measurement → rate.
- Quote standard specifications and BIS codes instead of repeating long details where appropriate.
- Specify tests and acceptance criteria.
- Avoid repetition and contradictory clauses.
- Be fair to both owner and contractor; realistic requirements.
- Use the imperative/future tense ("shall").
Detailed specifications of common items (outline)
Earthwork in excavation for foundations
- Site cleared; centre lines and trench widths marked from drawings; excavation to lines and levels.
- Bottom of trench levelled, rammed and watered; soft or loose pockets removed and filled with concrete or as directed.
- Excavated earth deposited at a specified distance from the edge of the trench; shoring/timbering and dewatering where necessary.
- Measurement in m³ as trench dimensions; rate includes lead and lift as specified.
Plain cement concrete (e.g. 1 : 4 : 8 in foundations)
- Materials: OPC/PPC as specified; clean, well-graded sand and hard broken stone aggregate of specified size.
- Mixing: in a mechanical mixer (hand mixing on a watertight platform where permitted), specified water–cement ratio.
- Placing and compaction: in layers not exceeding a specified thickness; compacted by rammers/vibrators; no segregation.
- Curing: kept wet for the specified period (commonly at least 7 days for OPC, longer for blended cements).
- Measurement: m³; no deduction for small embedded items.
Reinforced cement concrete
- Formwork rigid, watertight, true to line; reinforcement as per drawings and BBS, with specified cover blocks, laps and binding.
- Design mix concrete; slump and cube tests; placing within the initial setting time; vibration; construction joints at specified locations.
- Curing for the specified period; stripping of formwork after specified periods.
- Measurement in m³ (concrete), m² (formwork) and kg (steel), as specified in the item.
First-class brickwork in cement mortar
- Bricks: first-class, well burnt, of uniform size and colour, with metallic ringing sound, free from cracks; soaked in water before use.
- Mortar: cement and sand in specified proportions, used within the specified time (e.g. before initial setting).
- Laying: in English bond (unless specified), frog upwards, joints fully filled, joint thickness not exceeding about 10 mm; courses truly horizontal and walls plumb; not more than a specified height (commonly about 1 m) raised in a day.
- Curing: kept wet for about 7–10 days; joints raked for plastering/pointing.
- Measurement: m³.
Damp-proof course
- Typically cement concrete (e.g. 1 : 1.5 : 3), 40–50 mm thick with or without waterproofing compound, or bitumen coats as specified, over the full width of the wall at plinth level; not provided across door openings unless specified; cured.
Cement plastering
- Joints raked, surface cleaned and wetted; dots and screeds for uniform thickness.
- Mortar of specified proportions; applied in one or two coats as specified (e.g. 12 mm internal, 15–20 mm external in two coats).
- Finished with a wooden float/trowel; curing for about 7 days.
- Measurement in m² with IS 1200 deductions.
Flooring (cement concrete / tiles)
- Base concrete over compacted filling; floor laid in panels with dividing strips; specified slopes; curing; polishing/grinding for terrazzo; skirting as specified.
Whitewashing, colour washing and painting
- Surface cleaned, holes filled, priming where required.
- Lime wash/colour wash in specified number of coats, each coat allowed to dry.
- Paints (distemper, emulsion, enamel) applied as per manufacturer's instructions, with specified coats.
- Measurement in m² (with coefficients for doors, windows and grilles).