Short answer
Most cracking has an ordinary explanation. Thermal and moisture movement, drying shrinkage of new plaster or blockwork, and long-term settlement account for the majority of cracks in domestic buildings. Structurally significant cracking is less common and tends to be associated with foundation movement, subsidence, heave, overloading, failed or missing lintels, corroded wall ties or removal of structure without adequate support. Location, orientation, width, whether the crack passes through masonry units, and whether it is changing over time all help identify the cause.
Branded guidance note, prepared for project records and circulation to your team.
Common non-structural causes
- Thermal movement, particularly at junctions between materials
- Shrinkage of plaster, render and new blockwork
- Seasonal moisture movement in clay soils
- Differential movement between extension and original building
Signs that warrant an engineer
- Diagonal cracking wider than about 3 mm, tapering, stepped through mortar joints
- Cracks that pass through bricks rather than around them
- Doors and windows binding, or floors visibly out of level
- Cracking that is measurably widening over weeks or months
- Cracking above a beam or opening formed during previous alterations
How BES is typically involved
- BES inspects, measures and photographs cracking and forms a view on cause and significance.
- Where the cause is uncertain, a monitoring regime is specified with a defined review period.
- Remedial design follows only where it is genuinely justified.
Typical process
- 01Record crack locations, widths and dates
- 02Inspection and assessment
- 03Monitoring where the cause is unclear
- 04Diagnosis and report
- 05Remedial design if required
Common misconceptions
Commonly assumed
“All cracks mean subsidence.”
In practice
True subsidence is comparatively rare; most cracking is movement of a different kind.
Commonly assumed
“Filling a crack solves the problem.”
In practice
Repair without diagnosis hides the evidence. If the cause is active, the crack returns.
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Indicative result only. The calculation depends on the assumptions and information entered and does not constitute structural design or professional advice. Do not use the result for construction, procurement, Building Regulations submissions or safety-critical decisions. All results must be independently verified by a suitably qualified structural engineer before being used for design, construction or regulatory purposes. Bebbington Engineering Studio Ltd accepts no responsibility for reliance placed on unverified results.