IS 1200 — Method of Measurement of Building Works

Two people can measure the same wall and bill different amounts — unless they both follow IS 1200. It is the code that fixes what is measured, in what unit, and crucially what is deducted. It is the quiet referee behind every running bill, and the deduction rules are where contractor and client most often disagree.

Why a measurement code exists

Without an agreed method, every quantity is arguable: do you deduct the door opening from the plaster? Do you measure the plaster into the reveal? Is excavation paid by the pit or the neat dimension? IS 1200 answers these the same way for everyone, so a Bill of Quantities and a running bill can be checked rather than negotiated.

What is measured, and how

IS 1200 is issued in parts by trade — earthwork, concrete, masonry, plastering, flooring, steelwork and so on — and each fixes the unit and the rules:

Work	Typically measured in
Earthwork / excavation	cubic metre (m³)
Concrete (PCC / RCC)	cubic metre (m³)
Reinforcement steel	tonne / kg (by weight)
Brickwork	cubic metre (m³)
Plastering, flooring, painting	square metre (m²)
Skirting, cornice	running metre (m)

The deduction rules — where it bites

The rules that cause the most argument on a house are the deductions for openings:

Plastering: small openings up to a set area are not deducted — the reasoning is that the plaster to the reveal (the sides of the opening) roughly compensates for the face area lost. Larger openings are deducted, for one or both faces per the rule.
Brickwork: openings are deducted above a threshold, and lintels and jambs are measured to the code's convention.

You do not need to memorise the exact thresholds to benefit — you need to know that there is a rule, so that when a bill deducts nothing for a large window or deducts a small door twice, you can point to IS 1200 rather than argue by feel.

Estimation and reconciliation

The same code underpins the two estimation methods that must agree — the centre-line method and the long-wall / short-wall method — and the reconciliation of materials issued against materials that should have been consumed for the measured work. Being asked to reconcile the two estimation methods, or to state the plaster-deduction rule, is a standard quantity-surveying interview question.

Frequently asked questions

What is IS 1200? The Indian Standard method of measurement of building and civil engineering works — it fixes what is measured, in what unit, and what is deducted, so bills can be prepared and checked consistently.

How are openings deducted in plastering as per IS 1200? Small openings up to a set area are generally not deducted (the reveal plaster compensates); larger openings are deducted for one or both faces per the rule.

In what unit is brickwork measured? Brickwork is measured by volume (cubic metre); plastering, flooring and painting are measured by area (square metre); reinforcement is measured by weight.

Why does the method of measurement matter to a homeowner? Because it decides what you actually pay for. Two honest people can compute different quantities for the same work unless both follow IS 1200, so it is the reference that settles a disputed bill.