Maintenance and Repair of Masonry Works
This domain covers inspection, diagnosis, and repair of masonry defects such as cracks, efflorescence, water penetration, loose mortar, and damaged units. The exam tests whether you find the cause before patching, choose a compatible repair, and refer structural problems rather than hiding them.
Core rules
- Inspect and record the location, size, direction, and activity of cracks before repairing.
- Find the cause: movement, settlement, water penetration, thermal expansion, or poor original work.
- Rake out loose or defective mortar to sound material, clean the joint, dampen it, and repoint with a compatible mortar.
- Remove efflorescence by dry brushing and address the water source; do not simply paint over it.
- Replace cracked or spalled units where the damage affects strength or weathertightness.
- Refer diagonal, widening, or structural cracks to an engineer before cosmetic repair.
Worked example
A hairline crack follows a mortar joint on an external wall, with no displacement. Rake the joint back to sound mortar, clean out dust, dampen the joint, and repoint with a mortar similar in strength to the original. Cure the repair. The reasoning is that a hairline shrinkage crack can be repointed, but a diagonal crack that widens or crosses units may indicate movement and must be assessed structurally.
Traps
- Painting over efflorescence without stopping the water source.
- Using a rich, strong patch mortar against weak original masonry.
- Filling a movement crack rigidly without allowing for movement.
- Treating a structural crack as a cosmetic defect.
Key points
- Record crack location, size, and activity.
- Find the cause before repairing.
- Rake, clean, dampen, and repoint with compatible mortar.
- Stop the water source before treating efflorescence.
- Refer structural cracks to an engineer.