Amogh N P
✦ In loving memory of Amogh N P — Architect · Designer · Visionary ✦
A specification document beside material samples — ceramic tiles, paint swatches and a plaster sample: the quality of materials and workmanship the drawing cannot show.
Unit IVEstimation and Specification

Specifications

Defining the quality a drawing cannot show — general and detailed.

≈ 40 min + studio task

A drawing shows dimensions and arrangement but cannot convey the quality of materials and workmanship — the grade of cement, the mix, the curing, the finish. The specification supplies exactly this: drawing + specification + BOQ together fully define the work. Learn general vs detailed (item) specifications, the five-part anatomy of an item spec (materials, proportion, workmanship, measurement, rate), the spec ↔ BOQ ↔ rate link, sample specifications for brickwork and flooring, and the standard CPWD Specifications you reference by clause.

Learning objectives

By the end of this lesson, you will be able to — mapped to the course outcomes for Estimation and Specification:

1
CO4 · Understand

Explain why specifications exist and how they complete drawing + BOQ.

2
CO4 · Understand

Distinguish general from detailed (item) specifications.

3
CO4 · Apply

Write a detailed item specification with its five parts.

4
CO4 · Apply

Reference the standard CPWD Specifications and keep spec ↔ BOQ ↔ rate consistent.

Quality the drawing can't show

Why specs exist, and their types

Drawing (geometry) + specification (quality) + BOQ (quantity) together define the work; general specs give the class, detailed specs the full item.[2]

Three things fully define the work Drawinggeometry Specificationquality BOQquantity & cost A drawing shows geometry; the specification gives quality; the BOQ gives quantity and cost.
DiagramDrawing, specification and BOQ together fully define the work — geometry, quality and quantity

Quality, not geometry

A drawing shows dimensions and arrangement; it cannot convey the grade of cement, the mix proportion, the curing period, the finish or the tolerances. The specification supplies this. Together — drawing (geometry) + specification (quality) + BOQ (quantity & cost) — fully define the work. A vague or missing spec leads to disputes, poor work and unfair rates.[2]

General vs detailed General brief · per trade · approximate estimate Detailed (item) full · per item · detailed estimate & tender The detailed item specification minimises ambiguity — and disputes.
DiagramGeneral specification gives a brief class of work, while detailed item specification describes each item fully
Five parts, with samples

Writing the item spec

An item spec has five parts — materials, proportion, workmanship, measurement and rate — and maps onto the BOQ item and its rate.[2, 1]

Anatomy of an item spec 1 · Materials — source, grade, IS code, tests 2 · Proportion / mix — CM 1:6, M20 3 · Workmanship — laying, compaction, curing, finish 4 · Mode of measurement — unit & deductions (IS 1200) 5 · Rate — what the rate includes This maps one-to-one onto the BOQ item and its rate analysis — keep all three consistent.
DiagramThe five parts of an item specification — materials, proportion, workmanship, measurement and rate

First-class, CM 1:6

MATERIALS: first-class bricks (IS 1077), well-burnt, water absorption ≤ 20%; OPC 43 grade (IS 8112); clean sharp sand (IS 383); potable water. PROPORTION: cement mortar 1:6. WORKMANSHIP: bricks soaked until bubbling ceases; laid in English bond with broken vertical joints ≤ 10 mm, courses horizontal, wall plumb, joints raked for plaster; cured 7 days. MEASUREMENT: m³ per IS 1200 Part 3, openings deducted full, ≤0.1 m² ignored. RATE: includes bricks, mortar, scaffolding, labour, curing, T&P.[2, 3]

General vs detailed

At a glance

AspectGeneralDetailed (item)
DetailGeneral: brief, per tradeDetailed: full, per item
Used inGeneral: approximate estimateDetailed: detailed estimate & tender
DefinesGeneral: overall class of workDetailed: materials, workmanship, measurement, rate
Dispute riskGeneral: higher if relied onDetailed: minimises ambiguity
SourceWrite deviations onlyReference CPWD Specifications by clause
Vocabulary

Key terms

Specification

The written definition of materials and workmanship quality.

General specification

A brief trade-wise statement of the class of work.

Detailed (item) specification

A full per-item description of quality — the five parts.

Workmanship

The method and standard of executing the work (laying, curing, finishing).

Standard specification

A published reference spec (CPWD / IS) referenced by clause.

Rate inclusions

Everything the unit rate must cover, as defined by the spec.

Apply it

Studio task

Write a detailed item specification for first-class brickwork in CM 1:6, structured in the five parts (materials with IS codes, proportion, workmanship including soaking/bond/curing, the IS 1200 mode of measurement, and the rate inclusions). Then write a one-line general specification for the same building's plastering and flooring, and explain how the spec links to the BOQ item and its rate.

Check your understanding

Self-assessment

1. A specification primarily defines what a drawing cannot — namely —

2. Water absorption of a first-class brick should not exceed —

3. 'As per CPWD Specifications' in a BOQ refers to —

In a nutshell

Recap

A specification defines the quality of materials and workmanship a drawing cannot show.
General specs give the class of work per trade; detailed (item) specs describe each item fully.
An item spec has five parts: materials, proportion, workmanship, mode of measurement, and rate inclusions.
Keep spec ↔ BOQ ↔ rate consistent — the rate must cover everything the spec requires.
Reference the standard CPWD Specifications (and IS codes) by clause; write only project-specific deviations.
The evidence

References & further reading

  1. [1]CPWD, Specifications (current edition, multi-volume) — standard trade specifications.
  2. [2]B.N. Dutta, Estimating and Costing in Civil Engineering (specification chapter with samples).
  3. [3]BIS, IS 1077 (bricks), IS 456 (concrete), IS 383 (aggregates), IS 8112 (43-grade OPC).
  4. [4]M. Chakraborti, Estimating, Costing, Specification & Valuation (specification writing).
  5. [5]S.C. Rangwala, Estimating and Costing (general & detailed specifications).

Further reading

  • CPWD — Specifications (multi-volume, standard reference).
  • B.N. Dutta — Estimating and Costing in Civil Engineering.
  • M. Chakraborti — Estimating, Costing, Specification & Valuation.

Sources gathered and fact-checked June 2026. Published values vary by source, sample and method — treat as indicative and confirm against the cited standard before structural use.