Minimum wall thickness for single-storey loadbearing walls built in cement mortar 1:6 (cement:sand) – what is the recommended minimum?

Introduction / Context:
For loadbearing masonry in small buildings, minimum wall thickness ensures adequate compressive capacity, lateral stability, and robustness under openings and eccentricities. The mortar grade and wall height influence practical minimums used in byelaws and schedules of rates.

Given Data / Assumptions:

• Single-storey building.
• Masonry in cement mortar 1:6 (cement:sand) using standard bricks or blocks.
• Typical room heights and common live loads.

Concept / Approach:
Traditional practice adopts one-brick (approximately 20 cm) minimum thickness for external loadbearing walls in single-storey buildings to control slenderness and provide stability during out-of-plane wind suction. Thinner walls (10–15 cm) are often used as non-loadbearing partitions or with reinforced bands and stiffeners; thicker walls (25–30 cm) are reserved for higher loads or multi-storey construction.

Step-by-Step Solution:
Check slenderness: thinner walls reduce buckling resistance and increase damage risk.Consider mortar grade 1:6: adequate for one-brick walls under typical loads in single-storey buildings.Select the commonly recommended minimum: 20 cm.

Verification / Alternative check:
Many public works schedules and building byelaws cite about 20 cm as the minimum for external loadbearing walls at single-storey height where no special reinforcement is provided.

Why Other Options Are Wrong:
10–15 cm: generally used for partitions or non-loadbearing infill; too slender for primary loadbearing without special measures.25–30 cm: safe but not the minimum; increases cost and plan area.

Common Pitfalls:
Confusing non-loadbearing partitions with loadbearing walls; ignoring lateral stability and impact resistance around openings.

Final Answer:
20 cm.