The brick arch appears structurally unsafe.
The brick arch appears structurally unsafe. Perforated bricks have been laid in an unsuitable orientation, mortar joints are irregular and incompletely filled, and the crown lacks a properly formed and bonded keystone arrangement. The excessive mortar and poorly supported units at the apex do not provide a reliable compressive load path, creating a significant risk of local or complete collapse. The area should be immediately excluded, the centring retained or independently supported, and the arch assessed by a structural engineer before being carefully dismantled and rebuilt to an approved design.
- NCQLE reference
- NCQLE-2026-00006
- Quality topic
- Installation quality
- Lesson type
- Failure
- Evidence rating
- Documented
- Published
- 31 July 2026
- Last reviewed
- 31 July 2026
Evidence basis: Supported by reviewed project documentation. This learning is provided for professional consideration and does not replace project-specific competent advice, statutory duties or contractual requirements.
Context
During inspection of a newly constructed brick arch, while the timber centring remained in place, significant workmanship and structural concerns were identified. Perforated bricks had been laid in an unsuitable orientation, radial mortar joints were inconsistent and the crown had been formed largely with excessive mortar and poorly positioned units rather than a properly bonded keystone arrangement. The arch did not demonstrate a continuous compressive load path and was considered at risk of collapse if the temporary support were removed.
The transferable lesson
Masonry arches must be built to a verified structural design using bricks suitable for the intended orientation and loading. The arch geometry, abutments, radial joints, bonding and keystone arrangement must create a continuous compressive load path; excessive mortar cannot compensate for incorrectly positioned or unsuitable units. Competent supervision and inspection are required throughout construction, and the centring must not be removed until the completed arch has been checked, the mortar has achieved sufficient strength and formal approval has been given.
Recommended action
Immediately stop work, establish an exclusion zone and do not remove the existing centring. A competent structural engineer should assess the arch, temporary works and supporting abutments and specify any additional propping required. The defective arch should then be carefully dismantled under a controlled method statement and rebuilt to an approved design using suitable masonry units, correctly formed radial joints and a properly detailed crown or keystone. The rebuilt arch must be inspected and formally accepted before the centring is released
Limitations and application
The assessment is based on the visible construction only and cannot confirm the specified arch design, masonry strength, mortar specification, concealed reinforcement, supporting lintel or condition of the abutments. A decorative brick arch supported by a designed lintel may behave differently from a self-supporting structural masonry arch. The lesson therefore applies where masonry is intended to contribute to spanning or supporting the opening. Final conclusions and any temporary works, dismantling or rebuilding method must be determined by a competent structural engineer following a site inspection and review of the approved design.