Specifications & Measurement
The words that state quality — and the drawings only show quantity
The set is not finished with the drawings, because a drawing has a limit: it can show geometry, quantity and location — a 100 mm wall, here, this long — but it cannot show quality. It cannot draw that the paint is two coats to a given standard or the timber a named grade. That is the job of the specification, written clause by clause, and drawings plus specs together form the contract. And to turn a design into a cost, quantities are measured by an agreed mode of measurement (IS 1200), so the designer, contractor and client all count the same.
Learning objectives
By the end of this lesson, you will be able to — mapped to the course outcomes for Working Drawings & Detailing:
Explain why specifications are needed alongside drawings — quality versus geometry, quantity and location.
Write a clause-by-clause specification covering material, standard, execution, test and workmanship.
Apply the mode of measurement (IS 1200) and see how drawings and specs together form the contract.
Words complete the drawing
A drawing shows geometry, quantity and location; it cannot draw quality — the grade, standard, test and workmanship. Those are stated in the specification, in words. ‘The drawing says it all’ is a myth: drawings and specs together are the contract.[1, 2]
Quality the drawing can't show
A drawing can show GEOMETRY, QUANTITY and LOCATION — a 100 mm wall, here, this long — but it cannot show QUALITY. It cannot draw that the plaster is a particular mix, that the paint is two coats to a given IS standard, that the timber is a named species and grade, or that the workmanship must meet a tolerance. Those are stated in the SPECIFICATION, in words. 'The drawing says it all' is a MYTH: drawings and specifications describe DIFFERENT things, and a design is only fully defined when both exist.[1, 2]
Writing a specification
A spec is written clause by clause — each naming the material and its standard, the execution, any tests, and the manufacturer’s details. Its heart is referencing a defined standard (‘to IS 269’), not a vibe (‘good cement’) that invites a cheaper substitute.[2]
Clause by clause
A specification is written CLAUSE BY CLAUSE, trade by trade and material by material. Each clause states the MATERIAL and its standard (referencing an IS code, not a vibe — 'cement to IS 269', not 'good cement'), the EXECUTION (how it is prepared and applied, pre- and post-execution), any TESTS required, and the manufacturer's details where a proprietary product is named. Good specification is PRECISE and unambiguous: it should leave no room for a cheaper substitute or a lower standard to be slipped in, because the spec is what defends the quality on site.[2]
Mode of measurement
To turn a design into a cost, quantities are measured by an agreed mode of measurement — IS 1200 — so the designer, contractor and client all count the same. Documentation governs before (estimate) and after (verify) execution.[3]
How quantities are measured
Turning a design into a COST needs an agreed way to measure quantities, so everyone counts the same. In India that is the MODE OF MEASUREMENT — IS 1200, methods of measurement of building and civil engineering works — which, part by part (earthwork, concrete, flooring, plastering, painting and so on), defines exactly how each item is measured, what is included and what is deducted. Following it means a quantity measured by the designer, the contractor and the client all agree, which is the basis of a fair bill of quantities and the bridge to estimation and costing.[3]
At a glance
| Aspect | The fact | The folklore |
|---|---|---|
| A drawing shows | Geometry, quantity and LOCATION | Everything, including quality |
| Quality (grade, standard, workmanship) is stated in | The SPECIFICATION, in words | The drawing |
| A design is fully defined by | Drawings AND specifications together (the contract) | Drawings alone |
| A good spec clause references | A defined STANDARD ('to IS 269') | A vibe ('good cement') |
| Quantities are measured by | An agreed MODE of measurement (IS 1200) | Each person's own count |
| Documentation governs the job | Before AND after execution (estimate, then verify) | Only until it's issued |
Key terms
The written statement of QUALITY a drawing cannot show — material, standard, execution, test and workmanship — clause by clause; with the drawings, it forms the contract.
Drawings show geometry, quantity and location; specifications show quality. Different things — a design is only fully defined when both exist, read together.
A spec written trade by trade and material by material, each clause naming the material, its standard, execution, tests and manufacturer's requirements.
The mark of a strong spec: citing a defined standard ('to IS 269', 'Class 1') rather than a subjective word ('good', 'as approved') that invites substitution.
The Indian methods of measurement of building and civil works — how each item is measured, included and deducted — so all parties agree on quantities for a bill of quantities.
Documentation governs before (spec + estimated quantities for the bill) and after (tests verify quality, measurement confirms built quantities for payment).
Study task
Take one finished element from your interior set — a plastered and painted wall, a tiled floor, or a piece of joinery — and complete it as a document. First, confirm what the drawing already states (geometry, quantity, location). Then write the specification for it, clause by clause: the material and its standard (cite an IS code, not ‘good quality’), the execution pre- and post-work, any tests, and the workmanship required — precise enough that no cheaper substitute could be slipped in. Finally, using the idea of the mode of measurement (IS 1200), state how its quantity would be measured for the bill of quantities. The test is that your drawing and specification together define the work completely — the geometry from the drawing, the quality from the words — leaving nothing to the cheapest interpretation.
Self-assessment
1. What can a drawing NOT show, that a specification must?
2. What forms the contract that gets a design built?
3. What makes a specification clause strong?
4. What is the 'mode of measurement' (IS 1200)?
5. When does the documentation set stop governing the work?
Recap
References & further reading
- [1]Specifications and drawings as the contract — drawings show geometry/quantity/location, specifications show quality; the two together define the work (construction documentation practice; Interior Graphic Standards). https://www.wiley.com/
- [2]Specification writing — clause-by-clause material, standard, execution, test and workmanship; referencing IS codes rather than subjective terms (specification-writing practice, CPWD/standard specifications). https://www.bis.gov.in/
- [3]IS 1200 (multiple parts), Methods of Measurement of Building and Civil Engineering Works — the mode of measurement for bills of quantities (BIS). https://www.bis.gov.in/
Further reading
- Maryrose McGowan & Kelsey Kruse, Interior Graphic Standards.
- B.N. Dutta, Estimating and Costing in Civil Engineering (specifications and measurement).
- Ernst Neufert, Architects' Data.
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.
The author
Amogh N P
Architect, interior designer, and creative polymath. Studio Matrx began in his notebooks — his vision of design made honest, useful, and open to everyone. Its Academy is written and taught in his memory, and free, forever.
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