Building Construction – Expansion joints in long masonry walls For masonry walls in buildings, expansion joints are provided when the uninterrupted wall length exceeds which limit?

Introduction / Context:
Expansion joints accommodate thermal movement and shrinkage in long masonry walls. Without such joints, restraint can cause tensile cracking because masonry is weak in tension. Understanding when to introduce a joint is a basic design-and-construction decision that prevents unsightly cracks and serviceability issues.

Given Data / Assumptions:

• Masonry wall, long and largely unbroken by returns or movement joints.
• Standard building practice under typical temperature ranges.
• Objective: select the conventional threshold length for providing an expansion joint.

Concept / Approach:
Codes and handbooks give practical spacing limits so that thermal/ moisture movements do not accumulate to harmful levels. For ordinary brick masonry under typical climates, a widely adopted rule of thumb is to introduce movement (expansion) joints at about 30 m spacing when the wall has no natural breaks.

Step-by-Step Solution:
Identify the problem: long, continuous masonry accumulates thermal strain.Accept practical guidance: provide joints at about 30 m intervals.Choose the closest matching option: 30 m.

Verification / Alternative check:
Where walls are exposed to larger temperature swings or have stiff restraints, designers may reduce spacing below 30 m. Conversely, frequent buttresses/returns can function as partial movement breaks. Still, 30 m remains the common academic and exam reference value.

Why Other Options Are Wrong:

• 10 m and 20 m: overly conservative for standard practice; joints this close are rarely necessary in typical buildings.
• 40 m and 50 m: risk visible cracking before the joint relieves movement.

Common Pitfalls:
Confusing expansion joints in masonry with control joints in concrete; or assuming plaster/finishes will hide cracks (they usually telegraph through). Always coordinate joint locations with openings, architectural lines, and water-proofing details.

Final Answer:
30 m