Could the hot and dry summer of 2026 be contributing to cracks in your property?
The summer of 2026 has been exceptionally notable for prolonged periods of hot and dry weather across the UK. By mid-July, the UK had already experienced three widespread heatwaves, while 2026 became the first year in the UK weather record in which temperatures of 35°C or higher were recorded in May, June and July. The Met Office also reported that, by 15 July, 2026 had already recorded more days above 30°C than the whole of 1976.
The exceptional conditions began with a record-breaking heatwave in late May, when temperatures reached 35.1°C at Kew Gardens. A further major heatwave followed in June, with temperatures forecast to reach around 38°C in parts of southern England, before a third heatwave brought another prolonged period of hot and dry weather in July.
This combination of high temperatures, prolonged sunshine and below-average rainfall can have implications for buildings, particularly properties constructed on shrinkable clay soils.
Why can hot, dry weather cause cracks in buildings?
Large parts of London and the surrounding areas are underlain by clay soils, including London Clay. Clay soils can change volume depending on their moisture content. During prolonged dry weather, the moisture content of the soil can reduce, causing susceptible clay to shrink. When rainfall returns, the soil can gradually rehydrate and expand again.
This seasonal movement is often relatively small and may have little or no noticeable effect on a well-founded building. However, where the movement is significant, uneven or concentrated beneath part of a building, it can result in differential movement between different parts of the structure.
Older properties can be particularly susceptible where foundations are relatively shallow and extend into the near-surface soils affected by seasonal moisture changes. This can be relevant to many Victorian, Edwardian and Georgian properties, although the actual foundation construction and ground conditions should always be established rather than assumed.
The role of trees
Trees and other substantial vegetation can further increase the risk in shrinkable clay soils. Tree roots extract moisture from the surrounding ground, potentially causing additional drying and shrinkage. This can create differential movement where one part of a building is affected more than another, potentially resulting in cracking to walls and other elements.
However, the presence of a tree does not automatically mean that it is responsible for cracking or subsidence. Drainage defects, leaking pipes, alterations to a building, foundation conditions, ground conditions and other factors can also contribute to movement.
Why might cracks suddenly become noticeable?
Building movement does not necessarily occur as a single sudden event. In some cases, relatively small movements can accumulate over an extended period before cracking becomes visually apparent.
Existing cracks can also become more noticeable during periods of ground movement. Changes in temperature and moisture can cause some materials and existing defects to open and close, meaning that the appearance of a crack alone does not necessarily establish its cause.
When wetter conditions return, some moisture-related ground movement may partially reverse and certain cracks may reduce in width. However, this should not be taken as evidence that the underlying problem has been resolved. The extent to which movement reverses depends on the soil conditions, foundation arrangement, magnitude of movement and the underlying cause.
Does cracking mean my property has subsidence?
Not necessarily. Cracks in a property can have many causes, and not all cracking represents structural failure or subsidence. Minor cracking can arise from normal building movement, thermal effects, shrinkage of materials, previous alterations, settlement, moisture-related movement or local defects.
Where cracking is significant, progressive or accompanied by other signs of movement, however, it is important to establish the cause and determine whether there is any risk to the structural integrity of the building.
Signs that may warrant further investigation can include:
- New or progressively widening cracks;
- Diagonal cracks around openings such as windows and doors;
- Cracking that appears to extend through masonry rather than being limited to finishes;
- Doors or windows becoming difficult to open or close;
- Noticeable changes in floor levels;
- Separation between walls, ceilings or other elements;
- Cracking that appears to be concentrated in one part of the building;
- Evidence of movement that becomes more pronounced during prolonged dry weather.
These signs do not, by themselves, confirm subsidence. A proper assessment is required to determine the cause.
How should structural cracking be investigated?
The first step is to understand the pattern, location, width and progression of the cracking, together with the construction of the building and its surrounding ground conditions.
A structural engineer may consider:
- The location and characteristics of the cracks;
- Whether the cracking is internal, external or both;
- The age and construction of the property;
- Foundation type and depth, where relevant;
- Ground conditions and the presence of shrinkable clay;
- Nearby trees and vegetation;
- Drainage and underground services;
- Previous extensions, alterations or structural works;
- Evidence of differential movement;
- Whether the cracking is historic, seasonal or progressive.
Where necessary, further investigation such as crack monitoring, trial pits, drainage investigations or other specialist surveys may be recommended.
Structural Crack and Subsidence Assessments in London
If you have noticed new or worsening cracks following the prolonged hot and dry weather of 2026, it is important not to assume that the cracking is simply cosmetic or, alternatively, that it automatically indicates subsidence.
An appropriate structural assessment can help determine what is causing the movement, whether it is structurally significant and what action, if any, is required.
Structures Made Easy Ltd specialises in structural assessments for domestic properties, including Victorian, Edwardian, Georgian and other period properties throughout London and the surrounding areas.
We can assess properties where there are concerns regarding cracking, differential movement, settlement, subsidence, foundations and ground-related movement, and provide practical structural advice on the appropriate next steps.
If you are concerned about new or worsening cracks in your property following the prolonged dry weather, contact Structures Made Easy Ltd to arrange a structural assessment.
Why choose us?
With over 3000 successfully completed projects to date, we have consistently proven ourselves to be a leader in the industry. From design cross check procedures to quality control measures, we will ensure your project is completed to your exact specifications.
100% Success in Building Regs
Fully Qualified SE
Transparent Fees
Practical & Efficient Designs
Clear Advice
Fast Turnaround
We make all our processes as simple as
possible giving you peace of mind
STEP 1
Get a quote. Refer to enquiry form or email or speak to engineer
STEP 2
Arrange site inspection
STEP 3
Report delivered