Which of the following items is NOT typically measured in square metres (sq.m) under standard methods of measurement?

Introduction / Context:
Selecting the correct unit for measurement is fundamental in estimation and billing. Many thin or superficial items are measured by area, whereas structural concrete is generally measured by volume with separate items for formwork and reinforcement.

Given Data / Assumptions:

• D.P.C. is a thin layer at plinth or floors.
• Formwork is measured by its contact surface area.
• Concrete jaffries (jaalis) are perforated screens defined by plan area and thickness.
• R.C. chhajja is a reinforced concrete projection (slab) from the wall.

Concept / Approach:
Under common practice, structural R.C.C. is measured in cubic metres (cu.m), while its associated formwork is measured in sq.m and steel by weight. D.P.C. and jaffries are typically measured in sq.m due to their thin, superficial nature. Hence, among the options, R.C. chhajja is the item not generally measured in sq.m (the R.C.C. work itself is measured in cu.m, though finishes on it may be in sq.m).

Step-by-Step Solution:
D.P.C.: thin layer → sq.m — correct.Formwork: surface area → sq.m — correct.Concrete jaffries: screen area → sq.m — correct.R.C. chhajja (R.C.C. work): measured in cu.m; therefore NOT in sq.m.

Verification / Alternative check:
Standard measurement texts list R.C.C. works by volume with separate entries for shuttering and reinforcement.

Why Other Options Are Wrong:

• A, B, C are indeed measured in sq.m in conventional schedules.
• E is wrong because D is not measured in sq.m for the R.C.C. quantity itself.

Common Pitfalls:
Confusing the unit for the R.C.C. structural quantity with associated items (formwork/finishes) that are area-based.

Final Answer:
R.C. chhajja (projecting reinforced concrete slab)