- Bushing is more than specified (should not project more than 4 cm on exposed face and 1 cm on the face to be plastered).
- Stones not wetted before use.
- Mortar not mixed with mechical mixer.
- Proper bond between two connected walls not provided.
- Stones with round surface not to be used.
- Stones not tested for water absorption.
- Sand used has more silt content or contains harmful sulphates/ chemicals, fineness modulus not checked.