In building measurement, brick walls are measured in square metres (area measurement) when the wall thickness is which of the following?

Introduction / Context:
Measurement units for brickwork depend on thickness. Thin partitions are area-measured; full-thickness walls are volume-measured. This convention aligns the unit of measurement with how cost scales (per area for thin work, per volume for thick work).

Given Data / Assumptions:

• Standard brickwork thicknesses: half-brick ≈ 10 cm, three-quarter ≈ 15 cm, full-brick ≈ 20–23 cm (nominal).
• Payment unit changes from Sq m to Cu m as thickness increases.

Concept / Approach:
Half-brick (about 100 mm) partitions are treated as areal items because their thickness is a single leaf and the principal driver of cost is covered area. Thicker walls are measured in cubic metres since material consumption scales with volume.

Step-by-Step Solution:
1) Identify thickness = 10 cm ⇒ half-brick wall.2) Apply area measurement convention for partitions/half-brick walls.3) Conclude: 10 cm thickness → Sq m measurement.

Verification / Alternative check:
Methods of measurement and SORs list 'Half-brick masonry in cement mortar' with unit Sq m, confirming practice.

Why Other Options Are Wrong:

• 15 cm, 20 cm: Usually measured in Cu m as they approach or exceed one-brick thickness.
• None of these: Incorrect because 10 cm is the standard threshold for Sq m measurement.

Common Pitfalls:

• Measuring a 115 mm (nominal) partition in Cu m, leading to rate mismatches.
• Ignoring plaster thickness when computing wall areas (plaster measured separately).

Final Answer:
10 cm.