Cracks in walls are one of the most common reasons homeowners, buyers, sellers and mortgage lenders request a structural inspection. A crack does not automatically mean that a property is suffering from subsidence or that major structural work is required. The important question is what caused the crack, whether it is active, how significant it is, and whether further investigation is justified.
At Laytoe Structures, we inspect residential properties and provide structural reports for homeowners, buyers, mortgage and insurance purposes. This guide explains what different types of cracks can mean, when a structural inspection is appropriate, how subsidence is assessed, and what a mortgage-related structural survey can and cannot establish.
What can cause cracks in a property?
Cracking can arise from many different causes. Some cracks are superficial and relate to plaster, render, shrinkage or normal movement. Others may be associated with movement of the building, foundations, walls, roofs, lintels, drainage or changes to the structure.
- Shrinkage or thermal movement in plaster, render and masonry finishes.
- Minor seasonal movement caused by changes in temperature and moisture.
- Differential settlement or movement of foundations.
- Tree and vegetation influence, particularly where foundations are shallow and the underlying soil is shrinkable clay.
- Leaking or defective drainage that changes ground conditions or washes out supporting material.
- Alterations such as removal of walls, chimney breasts, openings or changes to roof loading.
- Defective lintels, inadequate support over openings or localised masonry movement.
- Historic movement that has stabilised and is no longer progressing.
When should a crack be investigated?
A structural inspection is particularly useful where cracking is new, widening, recurring, associated with distortion, or cannot be explained by the finishes alone. Cracks that are accompanied by sticking doors or windows, sloping floors, stepped masonry cracking, separation around openings, or visible movement of external walls deserve closer assessment.
The location and pattern of a crack are often more informative than its width alone. A structural engineer will consider the direction, distribution and relationship of cracking to openings, corners, floor levels, roof structure and foundations. The age and construction of the property, previous alterations, nearby trees, drainage and ground conditions may also be relevant.
What is a structural inspection?
A structural inspection is a targeted assessment of a particular structural concern. For example, an inspection may focus on cracking to a wall, a bay window, a floor and its supporting beams, a staircase, a retaining wall, or a suspected structural alteration.
The purpose is to identify visible structural defects, consider likely causes, explain their significance and recommend appropriate next steps. Where the available evidence is insufficient, the report may recommend further investigation such as monitoring, trial pits, drainage CCTV, opening-up works, soil investigation or specialist testing.
General Structural Inspection (GSI) for a property
A General Structural Inspection is broader than a targeted inspection. It considers the principal structural elements of the building, internally and externally, subject to reasonable access and the agreed scope. It can be useful for buyers who want an independent structural assessment before purchasing a property, particularly where cracking, movement or other structural concerns have been identified.
A structural inspection is not the same as a full building survey. A structural engineer focuses on structural condition and structural risk rather than providing a complete assessment of every building element, service installation or decorative finish.
Structural surveys for mortgages
Mortgage lenders and their valuers may sometimes request a structural engineer's report where there is evidence of cracking, movement, subsidence, an alteration to the structure or another concern affecting the property. The precise requirement depends on the lender, valuer and circumstances of the property.
A structural engineer's report can document the observed condition, discuss the likely cause of the defect, identify whether further investigation is required and set out recommendations. Where a lender specifically requires a report by a Chartered Structural Engineer, the report may need to be prepared or reviewed and signed by an appropriately chartered engineer. The lender's exact wording should always be checked before arranging the inspection.
Does cracking mean subsidence?
Not necessarily. Subsidence is only one possible explanation for cracking. In London and other areas with shrinkable clay soils, changes in soil moisture can contribute to foundation movement, particularly where vegetation is close to a building. However, cracking can also arise from settlement, thermal or moisture movement, localised defects, alterations, drainage problems or historic movement.
An engineer will normally look at the overall pattern rather than diagnosing subsidence from one crack in isolation. Relevant considerations can include the crack pattern, changes over time, vegetation, drainage, ground conditions, foundation type and depth where known, previous repairs and the construction of the property.
What investigations may be recommended for suspected subsidence?
- Crack monitoring over an appropriate period where movement needs to be established.
- Inspection of nearby trees and vegetation and consideration of their relationship with the building.
- Drainage investigation or CCTV where leaking or defective drains may be contributing to movement.
- Trial pits to establish foundation depth and construction where this information is necessary.
- Soil investigation where ground conditions require confirmation.
- Further opening-up or specialist investigation where the visible evidence is inconclusive.
Why monitoring can be important
A single inspection provides a snapshot of the property's condition. Where the key question is whether movement is continuing, monitoring can provide additional evidence over time. The appropriate monitoring period depends on the nature of the defect and the circumstances; the engineer should specify what is being monitored and how the results should be interpreted.
What should you do if you have found cracks before selling or buying?
Do not assume that every crack is a major defect, but do not conceal or ignore significant cracking either. Obtain an independent assessment where appropriate and keep records of previous repairs, monitoring, drainage investigations, tree works, underpinning or other structural work.
For a buyer, an independent structural inspection can help distinguish visible cosmetic cracking from issues that may require further investigation. For a seller, obtaining a clear structural report can help explain known defects and provide information for the buyer, valuer or lender.
What does a structural engineer's report usually include?
The content depends on the agreed scope, but a structural report will generally record the property and areas inspected, describe relevant observations, discuss the likely cause or possible causes, explain the structural significance, and provide recommendations. If the evidence is insufficient to reach a firm conclusion, the report should say so and identify what further information or investigation would be required.
When should you contact a structural engineer?
Consider obtaining professional advice if you are concerned about significant or progressive cracking, suspected subsidence, movement of walls or floors, structural alterations, failed or inadequate support, or a mortgage or insurance requirement for a structural engineer's report.
At Laytoe Structures, we provide structural inspections and reports for residential properties, including targeted structural inspections, General Structural Inspections and reports addressing specific structural concerns. If a mortgage lender or insurer has given you a particular reporting requirement, provide the wording before the inspection so the scope can be considered correctly.
Need a structural inspection or report?
If you are concerned about cracks, possible subsidence, structural movement or a mortgage-related structural requirement, contact Laytoe Structures to discuss the property and the scope of inspection required. The appropriate inspection depends on the issue being investigated and the requirements of the client, lender or insurer.