Lintel Failure in Houses: Causes, Signs, Structural Risks, Brick Lintels and Repair Options (UK Guide)
Lintel failure is a structural defect commonly identified in older and mid-20th century UK properties. It typically presents as cracking, sagging or distortion above windows and doors. While often less severe than foundation movement such as subsidence, failed lintels can compromise structural support if left unaddressed.
Because cracks above openings are frequently misinterpreted as subsidence, accurate diagnosis is essential. This comprehensive guide explains what lintels are, the different types used in UK homes (including brick lintels), why they fail, how to recognise warning signs, how surveyors assess severity, what repair options are available, and what it means for property buyers.
What Is a Lintel?
A lintel is a horizontal structural support positioned above openings such as windows, doors and garage entrances. Its purpose is to carry the load of masonry above the opening and transfer that load safely to the surrounding wall.
Without a properly functioning lintel, brickwork above an opening would sag or collapse. Lintels are therefore critical load-bearing components in many traditional masonry buildings.
Types of Lintels Found in UK Homes
1. Timber Lintels
Timber lintels are common in properties built before the early 20th century. While strong when dry, timber is vulnerable to rot, insect attack and moisture-related deterioration.
2. Steel Lintels
Steel lintels became widespread during the mid-20th century. Older mild steel lintels may corrode over time, particularly if exposed to moisture. As steel corrodes it expands, which can cause horizontal cracking and brick displacement.
3. Concrete Lintels
Concrete lintels are common in later construction. Although generally durable, they can crack if overloaded, poorly installed, or subject to structural movement.
4. Brick Lintels (Brick Arches and Soldier Courses)
In many traditional and Victorian properties, brick lintels were constructed using brick arches or soldier courses (vertical bricks laid above openings). These were often supported by concealed timber or steel elements, or designed to distribute loads through arch action.
Brick lintels rely heavily on correct load distribution and sound mortar joints. If supporting materials deteriorate, or if movement occurs in the surrounding masonry, cracking can develop within the brick arch or along mortar joints.
In some older homes, what appears to be a solid brick lintel may actually conceal a decayed timber support behind it.
What Is Lintel Failure?
Lintel failure occurs when the structural support above an opening deteriorates, weakens or becomes overloaded. Common mechanisms include corrosion of steel, rot in timber lintels, failure of concealed supports behind brick arches, inadequate bearing at each end, or increased loading due to structural alterations.
As lintels weaken, cracks often form above windows and doors. In more advanced cases, visible sagging, stepped cracking or distortion of brick arches may occur.
Common Causes of Lintel Failure
- Steel corrosion and expansion due to moisture ingress
- Timber rot caused by damp penetration
- Deterioration of concealed supports behind brick lintels
- Poor original installation or insufficient bearing length
- Structural alterations increasing load above openings
- Movement in surrounding masonry or foundation settlement
Signs of Lintel Failure
Common warning signs include:
- Horizontal cracks directly above openings
- Stepped cracks radiating from window or door corners
- Sagging or dipping brick arches
- Cracked soldier courses
- Rust staining on external masonry
- Difficulty opening or closing windows
- Bowed or distorted window frames
In brick arch lintels, cracking along mortar joints or visible sagging of the arch may indicate underlying support deterioration.
Lintel Failure vs Subsidence
Subsidence cracks are usually diagonal and extend beyond a single opening. Lintel-related cracks are typically localised above windows or doors and follow mortar joints or the curve of a brick arch.
Distinguishing between the two is essential to avoid unnecessary foundation investigations.
How Surveyors Assess Lintel and Brick Arch Issues
During a property survey, lintels are assessed visually where accessible. Surveyors consider crack patterns, building age, lintel type, signs of corrosion, and whether brick arches appear distorted.
Where concerns are identified, further investigation such as opening up internal finishes or structural engineer input may be recommended.
How Is Lintel Failure Repaired?
Repair typically involves replacing the affected lintel with a modern galvanised or stainless steel unit. Where brick arches are present, careful temporary support may be required before installing new structural support.
The process may include:
- Temporary structural propping
- Removal of affected masonry
- Installation of new lintel support
- Rebuilding brick arches or soldier courses
- Repointing and internal plaster repair
Final Thoughts
Lintel failure, including issues affecting brick arches and concealed supports, is a relatively common structural defect in UK homes. While cracks above openings can be alarming, they are often localised and repairable when correctly diagnosed.
Professional assessment through a comprehensive property survey ensures accurate diagnosis and appropriate remedial planning.
