The temperatures have dropped and Britain’s prolonged spell of hot, dry weather is behind us. But for structural engineers, the effects of the summer may not be.
At Harban Redwood, we have seen an increase in enquiries about cracking and suspected movement in buildings following this year’s exceptionally dry conditions.
For homeowners and property professionals, the timing can seem counterintuitive. If the extreme weather has passed, why are cracks attracting attention now?
The answer lies not in the temperature of the building, but in the condition of the ground beneath it.
The legacy of a dry summer
Prolonged dry conditions reduce the moisture content of the ground.
On shrinkable clay soils, that can be particularly significant. Clay changes volume according to its moisture content, shrinking as it dries and expanding as it rehydrates.
Where significant shrinkage occurs beneath foundations, particularly where it is uneven, the resulting differential movement can manifest itself in the structure above.
The hot weather may therefore be over, but the visible evidence of what happened beneath a building during that period can remain – or only now be attracting attention.
Older buildings with relatively shallow foundations can be particularly susceptible, as can properties where mature trees and large vegetation influence soil moisture levels.
The autumn after a dry summer is an important time to observe buildings
As conditions change, property owners, surveyors and other professionals should pay attention to cracking that has appeared or changed over recent months.
That doesn’t mean every newly discovered crack is evidence of subsidence.
Far from it.
Cracking occurs in buildings for numerous reasons, including drying shrinkage, thermal movement, historic settlement, structural alterations and movement between different materials.
This is why diagnosis based solely on the presence – or even the width – of a crack can be misleading.
For a structural engineer, the important questions are:
- Where is the crack?
- What pattern does it follow?
- Is it new?
- Is it changing?
- What else is happening elsewhere in the building?
And ultimately:
What has caused the movement, and is it continuing?
Look beyond the crack
The crack itself is only one piece of evidence.
Diagonal cracking around doors and windows, distortion of openings, sticking doors, corresponding internal and external cracking and changes elsewhere in the structure can all help build a picture.
The history and construction of the building also matter.
So do the foundations, surrounding ground conditions, drainage, vegetation and any alterations made to the property.
This is particularly important following an extreme weather event because there can be a natural tendency to attribute every crack to the most obvious explanation.
Dry ground and clay shrinkage may be responsible in some cases – but they aren’t the only potential causes.
Trees, drainage and the wider site
Mature vegetation is frequently part of the discussion around clay shrinkage.
During dry periods, trees continue to draw moisture from the ground, potentially increasing the effects of drying in susceptible soils.
However, assuming that removing a tree will solve the problem can create another risk.
Removing established vegetation changes the moisture demand on the surrounding soil. Rehydration of shrinkable clay can lead to swelling and, in some circumstances, heave.
Drainage should also form part of the investigation.
Damaged drains and leaking underground pipework can alter local ground conditions and contribute to movement. Previous structural alterations, nearby construction and changes in loading may also be relevant.
Effective diagnosis therefore requires the building, ground and surrounding environment to be considered together.
Don’t repair the evidence before understanding it
The instinctive response to a crack is often to repair it.
That may be premature.
Where recent movement is suspected, dated photographs, measurements and monitoring can help establish whether cracking is stable or continuing to develop.
Covering the crack immediately can remove useful evidence.
Monitoring can also prevent a rush towards unnecessarily significant remedial measures.
One of the biggest misconceptions surrounding suspected subsidence is that cracking inevitably leads to underpinning.
It doesn’t.
The appropriate engineering response depends on the cause, extent and progression of the movement.
In some cases, monitoring may be sufficient. In others, drainage repairs, maintenance or other relatively modest interventions may be appropriate.
More substantial structural or foundation work should only be considered where the evidence supports it.
Good engineering should be proportionate to the problem.
Why early structural advice matters
This is where structural engineers have an important role.
At Harban Redwood, an investigation into cracking begins by looking at the building as a whole rather than treating the visible defect in isolation.
That can include assessing the building’s construction and structural form, the location and pattern of cracking, likely ground and foundation conditions, drainage, surrounding vegetation and relevant alterations.
Where the initial evidence suggests further investigation is justified, this may lead to monitoring, drainage investigations, trial pits or other appropriate site investigation.
The objective is to establish enough information to answer two fundamental questions:
What is causing the movement?
What, if anything, needs to be done about it?
For architects, surveyors, property managers and other professional advisers, seeking structural input early can also help avoid unnecessary remedial work and ensure that the underlying cause is addressed rather than simply repairing the visible symptom.
An issue that extends beyond individual homes
The aftermath of this summer is also a reminder of a wider challenge facing the UK’s existing building stock.
Ground conditions aren’t static.
Changes in rainfall, temperature and soil moisture affect the environment in which foundations have to perform.
Many existing buildings – particularly older properties with relatively shallow foundations – were constructed under very different assumptions and have subsequently experienced decades of changing ground conditions, alterations, drainage changes and vegetation growth.
For new development, appropriate site investigation, foundation design, drainage and consideration of existing and proposed trees remain fundamental.
For existing buildings, understanding how those factors interact becomes increasingly important when signs of movement appear.
What should property professionals be doing now?
Following a prolonged hot and dry summer, this is a sensible time to encourage clients to pay attention to changes in their buildings.
New cracking shouldn’t automatically trigger alarm.
But neither should it automatically be filled and forgotten.
Record it.
Monitor it.
Look for associated changes.
Consider the wider building and site.
And where there is evidence of significant or continuing movement, seek appropriate professional advice.
The summer may be over, but buildings can continue to reveal what has been happening beneath them long after the temperatures have fallen.
The challenge is distinguishing harmless cracking from movement that requires action.
That’s where experienced structural assessment matters.
Harban Redwood provides structural engineering inspections and advice for residential and commercial properties, helping homeowners, property professionals and project teams investigate cracking, understand building movement and determine the most appropriate next steps.
Resi: Cracks appearing after the hot, dry Summer? Here’s what you need to know
The hot weather may have passed, but some homeowners and landlords are only now noticing signs of what this year’s long, dry summer may have left behind.
A new crack above a window. A line running across an internal wall that wasn’t there before. A door that’s suddenly difficult to close. Or an existing crack that seems to have become more noticeable.
At Harban Redwood, we’ve been receiving an increasing number of calls about cracking in properties following the prolonged hot and dry weather.
If you’ve spotted something similar, don’t panic. Cracks are common in buildings and don’t automatically mean there’s a serious structural problem.
But new or changing cracks shouldn’t simply be ignored either.
The important thing is understanding why the crack has appeared and whether the building is still moving.
Why can cracks appear after a hot, dry summer?
It might seem strange to notice a problem now that temperatures have fallen, but the issue isn’t necessarily the heat affecting the building itself.
It’s what the prolonged dry weather may have done to the ground beneath it.
Soils naturally contain moisture. After a long period with little rainfall, moisture levels can fall significantly.
This can be particularly important where a property is built on clay soil.
Clay can shrink as it dries. If the soil supporting a property’s foundations shrinks unevenly, one part of the building can move differently from another.
This can lead to cracking and, in some cases, subsidence.
The weather may have changed, but the signs of that movement can remain – and you may only now be noticing them.
Are some properties more at risk than others?
Ground conditions vary considerably, so two properties in the same area won’t necessarily respond in the same way.
However, some factors can increase the potential for movement.
Older properties may have relatively shallow foundations compared with modern buildings. Homes built on shrinkable clay can also be more susceptible to changes in soil moisture.
Nearby trees and large shrubs can be another factor.
During dry periods, established vegetation continues to draw water from the surrounding ground. On clay soils, this can contribute to further drying and shrinkage.
That doesn’t mean a nearby tree is automatically responsible for a crack – or that it should be removed.
In fact, removing a mature tree without understanding the ground conditions can sometimes create different problems as moisture returns to the soil.
Does a crack mean my property has subsidence?
No.
This is one of the most important things to remember.
Cracks appear in buildings for many reasons.
Plaster can shrink as it dries. Different building materials expand and contract. Properties settle over time. Older buildings may have cracks associated with movement that happened many years ago and has long since stopped.
Some cracking is therefore cosmetic rather than structural.
The challenge is knowing the difference.
Rather than simply asking “How big is the crack?”, it’s important to consider where it is, what shape it is, when it appeared and whether it’s changing.
What signs should you look out for?
If you’ve noticed cracking following the summer, take a closer look.
Things worth paying attention to include:
- New cracks that weren’t there previously.
- Existing cracks that are getting wider or longer.
- Diagonal cracks, particularly around doors and windows.
- Cracks around 3mm wide or greater.
- Doors or windows that have suddenly started sticking.
- Gaps appearing around windows, doors, floors or ceilings.
- Cracking that appears in a similar position both inside and outside the property.
- Several changes appearing at around the same time.
None of these signs alone proves that your property has subsidence.
However, if cracking is new, significant or changing, it’s sensible to investigate rather than simply decorate over it.
What should you do if you’ve found a new crack?
There are some straightforward steps you can take.
Take a photograph
Take a clear photograph of the crack and record the date. This gives you something to compare against later.
Measure it
If possible, measure approximately how wide and long the crack is and make a note.
Keep monitoring it
Check the crack periodically to see whether it changes. Where necessary, a crack monitor can be used to measure movement more accurately over time.
Look elsewhere
Don’t just focus on the most obvious crack.
Check other rooms and the outside of the property. Are there other signs of movement? Have doors or windows changed? Are there cracks in corresponding locations?
Don’t immediately fill and repaint it
If the crack is new, filling it straight away can make it harder to see whether movement is continuing.
It can be useful to monitor it first.
Don’t automatically blame the weather
The timing may make the summer an obvious suspect, but dry soil isn’t the only potential cause of building movement.
Cracking can also be associated with issues such as damaged drains, leaking underground pipes, previous structural alterations, foundation problems or other changes affecting the building.
That’s why identifying the cause matters.
Simply repairing the visible crack without understanding why it appeared could mean treating the symptom rather than the underlying problem.
What if you’re a landlord?
If a tenant reports new cracking, it’s worth taking it seriously and keeping a clear record of what has been reported.
Ask for dated photographs where possible and consider inspecting the property rather than relying solely on a description.
For landlords with several properties, particularly older buildings, this can also be a useful time to check whether any other properties have developed signs of movement following the dry weather.
If there is significant or worsening cracking, or other signs of movement, obtaining professional advice can help establish what is happening and what action may be appropriate.
It can also provide a useful professional record of the property’s condition and the recommended next steps.
Will my property need underpinning?
This is often one of the first concerns when people hear the word subsidence.
But cracking does not automatically mean underpinning is required.
Even if some structural movement has occurred, the appropriate response depends on the cause and whether that movement is continuing.
Sometimes monitoring is appropriate.
Sometimes another issue, such as drainage, needs addressing.
In other cases, structural repairs may be necessary.
More substantial foundation work may occasionally be required, but this should only be considered after the cause and extent of the problem have been properly investigated.
The aim should always be to find a solution that’s appropriate and proportionate to the problem.
When should you call a structural engineer?
If a tiny hairline crack has been unchanged for years, there may be little cause for concern.
However, professional advice is worth considering if:
- A crack has appeared recently.
- An existing crack is noticeably getting worse.
- There are several signs of movement.
- Doors or windows have started sticking.
- You’re concerned about the safety or condition of the property.
- You’re a landlord and need clarity about a problem reported by a tenant.
- You simply aren’t sure whether the cracking is cosmetic or potentially structural.
Getting advice doesn’t mean committing to expensive repairs.
Sometimes the most valuable outcome of an inspection is simply knowing what you’re dealing with.
How Harban Redwood can help
Harban Redwood’s structural engineers can investigate cracking and signs of movement in residential properties.
Rather than looking at a crack in isolation, we’ll consider the wider property and the factors that may be contributing to the problem.
Depending on the circumstances, this can include assessing:
- The pattern and location of the cracking.
- The construction and age of the property.
- Signs of movement elsewhere in the building.
- Ground and foundation conditions where known.
- Nearby trees and vegetation.
- Drainage and possible leaks.
- Previous extensions and structural alterations.
From there, we can advise whether the cracking appears to require further investigation or monitoring and recommend appropriate next steps.
Where additional investigation is necessary, we can explain what’s required and why.
And where remedial structural work is needed, Harban Redwood can provide the engineering expertise to help develop an appropriate solution.
The heat has gone. Don’t ignore what it’s left behind.
If you’ve noticed a new crack following this year’s hot, dry weather, there’s no need to assume the worst.
But there is value in understanding what your property is telling you.
Take photographs. Keep an eye on changes. And if the cracking is significant, worsening or causing concern, get professional advice before simply covering it up.
Harban Redwood provides practical structural engineering advice to homeowners, landlords and property professionals.
Concerned about cracking in your property? Get in touch with the Harban Redwood team to discuss the problem and whether a structural inspection would be appropriate.
