Specifications and Mode of Measurement

Float a one-line BOQ item - "Plastering to walls ... 500 sqm" - to three contractors and you will get three prices that differ by 30 or 40 percent. Not because one is cheap and one is greedy, but because each priced a different guess: 12 mm or 15 mm thick? Cement mortar 1:4 or 1:6? Internal or external? Scaffolding included? Curing included? The words were vague, so every bidder filled the silence in their own favour, and the cheapest guess wins the job and then fights for extras. Specifications exist to close that silence, and the mode of measurement clause decides how the words convert to money. This is the least glamorous lesson in the module and the one that prevents the most disputes.

What a specification is

A specification describes the quality of work: materials, proportions, workmanship, tolerances, and testing. Indian practice uses two levels:

• Brief specifications - one paragraph per major work item, used in preliminary estimates and small works ("230 mm brick masonry in CM 1:6 with bricks of minimum class 7.5 MPa...").
• Detailed specifications - the full method statement per trade: material standards (IS codes for cement, aggregate, bricks, steel), mixing, laying, curing, tolerances, and acceptance tests. Most Indian projects do not write these from scratch; they adopt a published standard - CPWD Specifications are the most common national reference, some states use their PWD equivalents - and then state only project-specific deviations.

The QS is rarely the author of specifications, but is always their heaviest user: every rate you analyse and every bill you check is priced against what the specification demands. A 1:4 plaster and a 1:6 plaster are different items with different cement consumption; specification changes are cost changes.

Anatomy of a BOQ item

A payable BOQ item description has recognisable parts, and each part carries money:

Walk through the example in the figure - a PCC item - part by part:

1. The work verb ("Providing and laying") defines scope: providing means the contractor supplies the material; laying means placement. "Fixing only" items, where the client supplies material, price completely differently.
2. Material and proportion ("cement concrete 1:2:4 with 20 mm nominal size graded aggregate") fixes the recipe the rate must cover. Change 1:2:4 to 1:1.5:3 and the cement content - and rate - changes.
3. Location and use ("in foundation and plinth") matters because the same material costs different amounts at different heights and access conditions; codes and schedules commonly separate work in foundation from work in superstructure.
4. Inclusions ("including compaction, curing, all leads and lifts") name the things the contractor cannot later claim as extras. Silent items become arguments; listed items become rate components.
5. Mode of measurement and unit ("measured net as laid; cum") states how quantity will be computed. This is where lesson 3 plugs in.

When you inherit a BOQ, audit items against these five parts. Every missing part is a future negotiation.

Mode of measurement: the contract's arithmetic clause

The mode of measurement answers one question per item: from drawing or site to number, by what rules? The practical hierarchy in India:

1. What the contract says - a measurement preamble or notes in the BOQ ("no deduction for openings up to 1 sqm in plaster", "steel measured inclusive of authorised laps only"). This governs.
2. The standard the contract adopts - usually IS 1200 (or CPWD practice, which is aligned with it for most trades).
3. Trade custom - only where both are silent, and dangerous to rely on.

Why would a contract override IS 1200? Usually simplification: a small-works contract may say "plaster measured flat, no deductions, no additions" to make site measurement fast. That is legitimate - if the bidders knew it when pricing. The dispute pattern to avoid is measuring one way and pricing another: a contractor who priced plaster expecting no deductions, then loses one-face deductions at billing, has genuinely been shortchanged - and vice versa. Mode of measurement is not a technicality; it is part of the price.

Worked example: two words worth eleven bags of cement

Item as floated: "Cement plaster to internal walls, 500 sqm." The bidder assumed 12 mm thick in CM 1:6. The client's engineer intended 15 mm in CM 1:4. Look at just the cement consequence of that silence, computed from first principles (assumptions stated: dry mortar volume taken as wet volume plus 30 percent for voids and wastage - a common estimating allowance; cement bag = 50 kg = about 0.0347 cum):

Twenty-four bags of cement apart - roughly ₹9,600 at an indicative ₹400 per bag (mid-2026; use current local prices) - plus proportionally more sand and labour, on one item of one small building. Neither party is dishonest; the words were incomplete. Now re-read the item as it should have been floated: "12 mm cement plaster in CM 1:4 to internal walls including curing and scaffolding, measured per IS 1200 - sqm." Every number in the rate analysis now has an anchor.

(The 30 percent dry-volume allowance is an estimating convention that varies by source and region between about 25 and 35 percent; Module 4 treats mortar constants properly. The point here is the money that hangs on the item's words, not the exact coefficient.)

Reading a specification like a QS

Three habits turn a specification from legal wallpaper into a working tool:

• Extract the measurable facts. Thickness, proportion, grade, size, tolerance - pull them into your takeoff notes next to the item. Your quantity sheet should never require re-opening the spec book to check what "plaster" meant.
• Hunt the "including" list. Scaffolding, curing, dewatering, leads and lifts, wastage, testing - whatever the rate includes cannot be claimed again as an extra. Whatever it excludes will be. Price and check bills accordingly.
• Flag spec-BOQ contradictions early. Where the BOQ says 1:6 and the specification book says 1:4, raise it before award, in writing. Contracts usually state a precedence order among documents; discovering it at billing time means someone has already lost money.

Specs in the RERA era - and on the smallest site

For RERA-registered projects the specification stopped being marketing copy: promoters are bound to the specifications promised in the agreement, and buyers commonly have a multi-year window after possession (five years is the widely cited period) to demand rectification of structural and workmanship defects. Treat that as commonly applied practice and confirm against the agreement and current rules - but the direction is unmistakable: the spec is now a liability document, and it is a large part of why organised developers maintain the full document chain from lesson 1. If you work developer-side, the specification you write today is the standard your snag-list liability is measured against years from now.

The same protection scales down to a self-builder dealing with a thekedar. An oral "achha kaam hoga" agreement becomes a one-page written spec annex behind the work order: wall thicknesses, mortar mixes, plaster thickness, concrete grades, a named brand list for cement and steel ("OPC 43 of brand X, Y, or equivalent"), and who pays for rework. Dealers substitute brands when supply tightens; a written "or equivalent" list lets you accept or reject a substitution without a fight. Two hours of writing beats months of dispute - the paper decides, at every scale of Indian construction.

Common mistakes

• Copy-pasting old BOQs. Yesterday's project's items carry yesterday's thicknesses, materials, and preambles into today's drawings - the single most common source of spec-drawing contradictions in small practice.
• Treating the unit column as decoration. An item written for sqm but united in cum (or rm) is unpriceable; unit and description must agree with the mode of measurement.
• Assuming IS 1200 applies when the preamble says otherwise - covered in lesson 3, and it bites in both directions.
• Ignoring "providing" versus "fixing only". Who supplies the material changes the rate several-fold; check every supply-and-fix assumption on client-supplied-material projects.
• Leaving proportions and thicknesses to custom. "As directed" and "as per standard practice" are dispute generators; numbers in the item are dispute killers.

Where this module leaves you

You now hold the four foundations: what the QS role is, how to read the drawing set, the units and IS 1200 rules that govern measurement, the estimate ladder, and the words that bind quantity to money. Module 2 puts them to work on real takeoff, starting where every building starts - setting out, excavation, and the substructure - with the centreline method as your primary tool.