In building measurements and billing, which of the following steelwork items are typically measured in square metres (sq.m)?

Introduction / Context:
Quantity surveying requires selecting the correct unit of measurement for each work item to ensure consistent estimation, tendering, and billing. Many fabricated sheeted or framed openings are measured by area (sq.m) rather than by weight or running length.

Given Data / Assumptions:

• The items listed are common in architectural and structural steelwork for buildings.
• Standard measurement practices (PWD/CPWD-type conventions) are assumed.
• We are to identify which of the items are measured in sq.m.

Concept / Approach:
Items covering openings—such as collapsible gates, rolling shutters, steel doors, and ventilators/glazing—are priced per unit area because their cost scales with size in two dimensions, accounting for framing, panels, sheeting, and hardware within standard specifications.

Step-by-Step Solution:
Collapsible gates: measured in sq.m of clear opening covered — yes.Rolling shutters: quoted per sq.m including curtain, guides, and accessories — yes.Steel doors: area measurement is standard, including frame and shutter as specified — yes.Ventilators and glazing: glassed area or framed ventilator area is measured in sq.m — yes.Therefore, “All the above” is correct.

Verification / Alternative check:
Standard schedule of rates commonly lists these items with area-based descriptions, with separate items for hardware or special finishes as applicable.

Why Other Options Are Wrong:

• Any single option alone is incomplete, since all listed items use area units in typical practice.

Common Pitfalls:
Measuring shutters or doors by running metre or by weight; omitting allowances for grills, glazing thickness, or specified frame sections.

Final Answer:
All the above.