The number of enquiries we have received for Structural Engineers Reports during July and August of this year has been at record levels, reflecting the dry summer and the consequential cracking and subsidence of our housing stock.

Fortunately, most damage is minor and can easily be dealt with via simple inexpensive crack repairs.

The most important issue is to establish the likely cause of the cracking and to try and prevent future worsening of cracks. This may involve addressing problematic trees, particularly on clay soils, or repairing leaking drains, which is less common on granular soils and generally not linked to dry summers.

For sellers – a Certificate of Structural Adequacy

For those currently in the process of selling their house it is important to check there are no significant cracks in the property. If there are, the sale process can normally still proceed but it will be a much smoother process if the vendor obtains an up front Structural Engineers Report which can be shared with prospective buyers. In cases where the report is favourable SERL can, by separate, additional, agreement, issue a Certificate of Structural Adequacy.

For buyers – a Structural Engineer’s Report

For those buying a property at this time it is more important than ever to check the property is sound and is not showing signs of subsidence, or cracking which might indicate the early onset of subsidence. Only a Structural Engineers Report will provide this sort of information although a RICS Surveyors Report will often provide initial useful general guidance. 

More information provided by the Met Office on the 2025 drought:

The UK has experienced one of its driest and warmest summers in decades, according to the latest data from the Met Office. The severe drought conditions seen in 2025 have followed what was already the driest spring in over 100 years, with rainfall between January and July at its lowest since 1929. By mid-May, rainfall was nearly 30% below average, and summer rainfall has since remained far below normal levels, with the UK receiving just 72% of the typical summer precipitation by mid-August.

The most affected areas have been central and southern England and much of Wales, where rainfall levels dropped as low as 59% of the long-term seasonal average. Scotland fared slightly better, with some regions seeing closer to average rainfall. The Met Office attributes the prolonged dry period to persistent high-pressure systems that deflected rain-bearing weather fronts away from the UK.

The impact of drought on agriculture

The drought’s impact has been widely felt across agriculture, water resources, and ecosystems. Supermarket chain Waitrose reported that the autumn harvest began nearly two weeks early due to heat stress on crops, while some vegetable yields, including broccoli, have declined by more than 50%. Water usage restrictions have been introduced in parts of England in the form of hosepipe bans, and farmers have raised concerns about long-term soil degradation and crop viability if dry conditions persist into the autumn.

Although summer 2025 has not yet officially surpassed the infamous 1976 drought, which remains the benchmark for extreme dry weather in the UK, the Met Office and other climate analysts note that 2025 is likely to be remembered as one of the most impactful in recent memory. The combination of unusually low rainfall, sustained high temperatures, and repeated heatwaves, four in total, has created conditions of widespread water stress.

Government action needed on water conservation

The likelihood of continued drought remains high. Without significant rainfall in September, long-term water reserves and groundwater levels may not recover adequately before winter. The Met Office has urged both government bodies and the public to conserve water and prepare for the potential of extended drought into the later months of the year.

In conclusion, this summer has not only tested the UK’s agricultural resilience but has also highlighted growing concerns around climate volatility. With droughts expected to become more frequent and intense due to climate change, the events of this summer serve as a stark warning for the need to prepare for the future.

The post The impact of this summer’s drought and what it means to homeowners appeared first on Structural Engineers Report.

While the majority of our structural engineers’ reports result from surveyors reports’ and lenders’ valuation surveys, an increasing number of reports are arising from buildings insurance and specifically subsidence cover issues.

These problems include:

1. a) Buyers who are unable to obtain subsidence insurance
2. b) Buyers who are unable to secure a mortgage because of historic underpinning or insurance claims.
3. c) Vendors who are unable to sell their home as there is no subsidence insurance in place.
4. d) Vendors who are unable to sell their property because of historic underpinning or minor subsidence claims and superficial repairs, for example, redecoration.
5. e) Owners insurance premiums increase or even withdrawn without notice.
6. f) Owners who require a structural engineers report to support their application for new insurance terms
7. g) Owners re mortgaging are asked for a Certificate of Structural Adequacy to secure new funding even thought current insurance includes subsidence.
8. h) Owners subsidence insurance is withdrawn after they have made a claim or even merely notifying the insurer of damage without submitting a claim.

So why are there so many insurance problems related to subsidence?

Readers will see from the points above that the entire property chain, ranging from simple home ownership to buying and selling, is fraught with subsidence insurance issues.

Whilst we are not insurance experts, we believe that many of the issues arise from a simple lack of understanding of the subject. The following points are clear to us:

1. a) Property prices are so high that the general public, including insurance company employees, instinctively view cracks in buildings, such as houses and flats, as a significant concern or risk.
2. b) Most people believe that any cracks in houses are an issue, however, most are not.
3. c) Many people think that cracks in houses are expensive to repair and will jeopardise the process of buying and selling a property. In reality, most cracks are neither serious nor expensive to repair especially when compared to the property’s value.
4. d) Insurance companies do not employ technical experts, such as chartered structural engineers, which means they often don’t fully understand the technical issues. Instead they rely on binary computer-generated answers to standardise questions, which is too simplistic a methodology.

Discussion

The starting point with all of these issues is the “risk” specifically “perceived risk”. It all stems from a misunderstanding of how buildings behave and what cracks mean or do not mean. Fear of the unknown perpetuates anxiety until an experienced Chartered Structural Engineer provides a report and clarifies the situation.

It is a requirement of any domestic mortgage that the buyer or owner includes subsidence insurance as part of their buildings insurance policy. The insurance industry provides associated insurance and has to price the risk and ensure premiums to cover the overall costs and contribute to profits, similar to other types of insurance.

Between the 1970s and the 1990s, insurance policy excesses were typically low, around £500. Consequently, large numbers of the public did not hesitate to file insurance claims for minor issues such as small cracks or seasonal movement since the cost of repairs and redecoration nearly always exceeded the policy excess. As an unintended benefit, this often resulted in many rooms being newly decorated leaving them as good as new.

Whilst this article is not the place for a technical engineering thesis, it is fair to say that the subsidence industry, including engineers and surveyors, were somewhat overzealous when dealing with small amounts of cracking. This resulted in expensive underpinning schemes being carried out at huge cost, which was disproportionate to the cost of simply repairing the damage and dealing with offending trees. This legacy has resulted in owners, buyers and insurers being nervous of the terms ‘subsidence’ and ‘underpinning’ as these convey both expense and risk!

These days, it is uncommon to see properties being underpinned. Instead, issues such as tree roots or leaking drains are addressed, followed by straightforward and cost-effective crack repairs.

Insurance primarily aims to repair and restore the pre-damage condition rather than improve it or prevent future damage. A helpful analogy is that of a vintage car: if a fault develops, it is repaired, but the car does not become like new, and the same issue may arise again. Insurance companies have become more stringent in handling claims and prefer to repair damage even at the risk of future repairs, as this is potentially less costly than investing significantly more to prevent recurrence.

As a consequence, the cost of insurance per claim has reduced significantly, yet many household insurance companies are unprepared to offer simple and affordable terms to most domestic homeowners. This leads us to believe that the past perception of expensive underpinning is unfounded.

Why do we all worry about cracks?

This article is not a technical thesis on cracks and the human and engineering implications but it is important to emphasise that most of the issues discussed here are a result of people misunderstanding cracks and what they mean for residential property. Those interested to read more can see separate articles on our blog website about subsidence and minor cracks.

Previous claims and underpinning

Insurance companies often penalise property owners or buyers who have a history of previous insurance claims, especially if underpinning has been carried out. While various issues may arise from this stance, it often lacks sense from a technical and engineering perspective. Insurance firms most likely use simplified algorithms for these evaluations, as employing a structural engineer to assess each case individually is unrealistic. However, property owners or buyers can seek their own expert by employing a chartered structural engineer to assess the situation more accurately and provide a structural engineers’ report.

In the majority of our inspections and reports, where previous insurance claims have been made or underpinning has been carried out, we find that the current and future risks are no different to those of many similar properties in the same geographical area, sharing a similar architectural style and foundations. With over 30 years of experience, it appears that the criteria used by insurers and brokers are far too simplistic, leading to broad generalisations that cause problems for numerous homeowners and potential buyers.

What should you do?

Most of the issues discussed are unfortunate and frequently avoidable if there was a greater involvement of engineers in the decision-making process. This is unlikely to change given the sheer size of the insurance world. However, homeowners and potential buyers can significantly influence the decision making processes by exercising due diligence. This involves appointing an experience Chartered Structural Engineer to advise them. And the insurance company should be reassured by the subsequent detailed report. At the very least, it will provide essential engineering facts and give the insurance company concrete information on which to base their decisions (no pun intended!).

Although this is an extra task and expense, it can be crucial for securing subsidence insurance, which may affect the ability to purchase certain properties. For existing homeowners, it may significantly impact future annual insurance premiums. In many cases, the report’s cost can be recouped within one or two years through substantial insurance savings.

Should you require further advice or have any questions then do call SERL on 020 8161 9900 or contact us and we’ll be delighted to help.

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When purchasing a property in Greater London, contacting the Local Authority as part of your searches will provide guidance on the risks of subsidence, landslip, and heave. This information is based on statistical factors such as local geology and insurance company data on subsidence claims in your postcode.

Subsidence claims are most frequent where London Clay is near the ground surface and large mature trees are nearby. Consequently, the risk to a specific property depends on various factors, though some general tips and guidance can be offered.

While this advice is intended to inform, it is not meant to alarm potential buyers or sellers or suggest that all properties in a particular London area, town, or postcode are affected by these risks. On the contrary, due to proactive measures by most Local Authorities to maintain trees, these risks have decreased in recent years.

The following general guidance may be of interest:

1. Geological Map of London, the South East, and the UK

The British Geological Society (BGS) offers a free website and app that provides likely geological details for any postcode. This resource needs careful use but can help establish whether a property is located on clay soil.

The map uses two distinct layers to show the deep underlying bedrock, i.e. the soil very deep below the ground, together with the superficial geology which is the most important soil type as this is closest to ground level. This is likely to be the soil type found immediately below most foundations in period houses built before the war and even before 1976.

If no superficial geology information is recorded for a postcode, this indicates that the surface geology is the same as the bedrock – generally London Clay in most of Greater London, or chalk near the North Downs in Surrey, for example.

General soil types and associated risks:

– London Clay: High risk of subsidence especially with large nearby trees.

– Head: Intermediate risk with nearby trees.

– Alluvium: Soft soil with a risk of historic settlement.

– Langley Silts: Clay with silt.

– Gravel Soils (e.g. Kempton Park, Taplow, Lynch Hill, Hackney) – Generally more strong and stable than clays and other soils listed above.

2. Trees

Most significant subsidence cases on clay soils involve trees or mature shrubs. The risk of subsidence depends on the location and size of the tree if the superficial or outcropping bedrock is clay-based. Conversely, stable soils like sand, gravel, or chalk reduce this risk. However, large trees can disrupt drains, potentially leading to subsidence due to soil softening or erosion.

Useful guidance regarding trees:

a) Consider the proximity of the tree to the house. If a tree’s height exceeds its distance from the house, root systems likely extend beneath the property.

b) Determine if the tree is within your control (i.e. within your property boundary) or on neighbouring or local authority land.

c) Check if the tree is protected by a preservation order or if the property is within a conservation area, requiring local authority approval for any alterations.

d) If a tree is suspected to cause subsidence damage, the tree owner may need proof, such as soil and root testing, to address the issue.

3. Drainage Issues and Loose Soils

Period houses often rest on manmade materials known as fill, covering London’s natural geology, whether gravels or clays. As a general guide, if loose soils are near the surface and below the house foundations, softening and erosion may occur, especially with poorly maintained drains located beneath or adjacent to the house. Subsidence can result from drains even when sands and gravels are close to the surface, not just clay soils. Given that drain surveys are relatively inexpensive, it is prudent to include these in early maintenance plans when purchasing a property. Requests to test drains pre-purchase can delay transactions, with some vendors reluctant to undertake such testing. Fortunately, drainage repairs are typically affordable, often costing a few thousand pounds rather than tens of thousands.

4. Foundation Depths

Subsidence risk is heavily influenced by foundation depth. Shallow foundations are more susceptible to soil drying out and shrinking during summer, tree root intrusion, and proximity to drains. Deeper foundations are generally more stable, with reduced susceptibility to seasonal soil volume changes and tree root impact. Modern properties typically feature deeper and more robust foundations, especially following the design improvements post-1976 after the significant summer drought.

Houses with cellars benefit from naturally deeper and more stable foundations. Houses with lower ground floors are usually better protected by having most of the property and foundations significantly below street level where trees are located. This might not apply to trees in rear gardens, however, where the external ground level is often close to lower ground floor level.

Foundation Depth Guide:

– Pre-1920: 30 cm to 45 cm

– 1920-1930s: 45 cm to 60 cm

– 1950-1975: 60 cm to 1 m

– Post-1976: 1 m or deeper

5. Building Regulations Approved or Engineer-Designed Foundations

Modern foundations are generally more robust, particularly if approved by the Local Authority Building Control Department or designed by a Chartered Structural or Civil Engineer based on soil testing and considering the mature height of nearby trees.

Note: that self-contained conservatories with external doors to the main house often do not comply with Building Regulations.

Local Authority approvals are based on current site conditions, not future tree heights, and the Authority holds no design liability. Therefore, consulting a reputable firm of chartered Structural Engineers for foundation designs of extensions and new constructions is advisable.

The National House Building Council (NHBC) offers extensive guidance to designers and developers for building near trees on clay soils, considering the soil’s shrinkage characteristics determined by testing or assumed worst-case scenarios. Tall trees, such as large oaks, London Planes, and Poplars, can necessitate foundation depths or underpinning up to 3.5 meters.

For new foundations exceeding about 2 meters, alternative methods like bored piles, concrete stilts drilled deep into the ground with a reinforced slab or a series of linking beams on top, are often more economical and practical.

Conclusions

This article serves as a general overview and should not be used in isolation without obtaining location-specific advice from relevant professionals, such as a local chartered structural engineer. It aims to provide valuable insights for property owners and non-engineering professionals, including solicitors, general practice surveyors, and estate agents, on broad geological and structural matters.

The paper introduces the geology of the London area and provides guidance on how to use the British Geology viewer map or app to identify the most likely soil type for a specific address or postcode. It explains the distinction between bedrock and superficial geology, as well as the differences between clay soils and gravel/sandy soils. Guidance is also provided on typical foundation depths for buildings of different ages.

This article highlights the importance of considering trees on clay-based soil, and the potential mature height of a tree if it isn’t controlled. This is crucial when designing foundations for extensions or new buildings. While it aims to be informative, we recommended you consult with a chartered structural engineer for more specific advice.

The post Subsidence risks for properties in London appeared first on Structural Engineers Report.

Why do we all find much more movement and cracking specifically within the rear addition/projection compared to the front elevation, when considering mid terraced Victorian houses in London.

Any discrepancy between the amount of trees to front and rear can be ignored. Bay window projections are also excluded for discussion purposes.

The answer

The answer, prior to the explanation, is simply due to the relative lack of lateral restraint or buttressing of a rear addition compared to the continuous nature of the front elevation.

The explanation

To be read with the sketch Sk13 (a to d) below.

Diagram (a) shows a front elevation of four houses with the subject house coloured green.

Diagram (b) shows its plan form with continuity of the front elevation, with rear projection adjoining its neighbour to the right. The letter “J” denotes a joint between abutting walls, often where the party walls abut the front elevation, where the flank wall abuts the main rear wall and also often within the party wall where there is sometimes a joint or gap (Used for the old lead pipes for the water tank) but more commonly poor bonding of brickwork.

Diagram (c) shows a simple isometric demonstrating how the rear projection is free to tilt away from the main house and to a lesser extent away from its neighbour.

Diagram (d) replicates the previous question 1 for ease of reference where we explored the subsidence to the right hand side of the frontage with tapered diagonal cracks emanating from the free edge at the top flank corner and gradually propagating downwards to the pivot point near the front door.

Overview

If we step back from our detailed site surveys and Structural Engineers reports for a moment we can consider the structural “form” of different building types whether they are framed steel or concrete office blocks or, in this instance, very simple plain brickwork housing stock.

In their purest forms, houses are a series of boxes.When a terrace is formed, with one long elevation at the front and a number of rear projections at the back, we have a number of boxes but connected together to become stronger, at least as far as the front and main rear elevation are concerned.

The rear projections are normally pairs of boxes twinned with the neighbour in respect of its rear wall but remain a single box structure with regard to the flank wall.

Unfortunately, whilst a box structure is normally strong when the corners are rigidly connected, many Victorian houses have gaps or joints between abutting walls, and in particular with regards to the rear projections. This is because they were invariably built by different teams of people, a number of weeks after the main house was built and with little regard, in many instances, to connecting the two structures together.

Whereas, the front elevation of a mid terraced house is sandwiched in between other houses and forms part of a much longer and continuous wall structure, a rear projection. As the name infers it is a “projection” from the general building line and, therefore, lacks any lateral support by comparison.

The enclosed diagram indicates the compressive or lateral restraint of this elevation if it tries to tilt within its vertical plane as per the detached or end of terrace house, as explained in a previous article.

The plan diagram (b) and simple isometric diagram (c) shows how the flank wall of the rear projection and the rear wall, to a lesser extent, is free to rotate when subsidence of the ground occurs. NB subsidence magnitude is not uniform and occurs greatest nearer a tree.

In Quiz question 1 we explored how unrestrained walls, such as those of a detached or an end of terrace, tend to tilt and rotate as a consequence of foundation movement. See diagram (d) on SK13. The rear projection flank walls behave in the same way, as do bay window projections.

There are multiple reasons why a rear projection might subside, many mentioned in the various comments thank you. It is the shape and form which allows the rear addition to move, assuming all other factors are broadly equal.

By way of general observations the most common causes of rear addition subsidence (Modern day movement), compared to the front elevation, tend to be;

1. Located nearest mature and or more frequent trees and large shrubs.
2. Drainage passes parallel and often below flank wall footings.
3. Lack of bonding or tying-in to main rear wall or house party wall.
4. Shallower foundations than the main house, particularly when the cellar is under the hallway and stairs.

Other common defects found within rear projections but which do not particularly contribute to the foundation movement discussion include;

• Poor brickwork quality generally, compared with frontage
• Poor bonding with the use of snapped headers.
• Built in timbers including backing lintels to brick arches
• Lack of lateral restraint perpendicular to floor span.
• Overloading of first floor joists from heady partition loads and roof props.
• Mono pitched roofs often undersized. Often no loft access to assess.

Watch this space and on Linkedin for further quiz questions and discussions.

The post Linkedin Quiz Question 3 Monday 4th November 2023 appeared first on Structural Engineers Report.

What is subsidence

Subsidence is the general term used to describe the downward movement of the ground and consequently a building resting upon it. More specifically we normally refer to the consequent cracking or structural damage that results.

Subsidence causes vary, depending on the type of soil, trees, drains and type of foundations beneath the property.

Most subsidence takes the form of minor cracking which is easily repaired from time to time but in extreme cases more significant repairs are required. Sometimes the cause of subsidence can be dealt with but on other occasions it cannot realistically be completely eliminated in the future. See later.

Why do we worry about subsidence?

The term subsidence can sound overly dramatic as it conveys images of buildings sinking into deep mining holes are sliding off steep cliff faces and generally causing catastrophic damage to our valuable homes.

In reality the above is rarely the case and particularly in London and the Home Counties where the geology is relatively uniform and well known, albeit prone to perhaps more frequent but minor damage in most instances.

The term subsidence has repercussions depending on circumstance and status eg whether owning, buying, selling or renting property and some of the main concerns for each of these status are as follows;

For homeowners

• Repair costs might be significant if the damage is not covered by Building Insurance and more specifically Subsidence Insurance. The normal policy excess is typically £ 1500.
• Making a Subsidence claim can be detrimental to future insurance premiums. In some instances, Insurance companies withdraw Insurance cover after making a claim which is very harsh.
• If minor cracking damage reoccurs regularly but does not exceed the policy excess, year on year repair costs can mount up and reoccurring cracking is a nuisance visually.
• In extreme cases internal repairs or strengthening such as underpinning or piling would necessitate moving out of the family home for many months whilst repairs are carried out. Whilst this is extremely rare in practice, the potential of this risk is what triggers a natural fear of subsidence.

For those selling

• Subsidence damage may prevent or restrict the sale of a property in terms of market appeal and potentially lower the sale price. See below.
• It is important to obtain professional advice from a Chartered Structural Engineer prior to sale, which might be shared with a prospective buyer, in order to smooth the sale process.

For buyers

• Many buyers will simply be put off buying a property with a current subsidence problem, for fear of costs of repairs and disruption to day to day living.
• It is difficult to obtain a mortgage, and Buildings Insurance, against a property with a current or ongoing subsidence problem even if the damage is minor, for fear of it becoming worse and expensive to resolve.
• A structural engineer’s report is almost bound to be required for any property showing recent signs of cracking, which might indicate a current or ongoing subsidence problem.

Estate Agent’s advice note

We always encourage Agents to recommend that a vendor obtains a Structural Engineers Report from a professional structural engineer when there are obvious cracks and signs of subsidence or historic settlement cracking. This report will inform the owners repairing options pre-marketing for sale, or alternatively, to share the report with prospective buyers on an open book basis so they can be informed at the earliest opportunity. This avoids wasted time and money later and can avoid disappointment all round.

Surveyor’s Reports

Depending on the type of RICS report and on the experience and knowledge of the surveyor, it is common for the general practice surveyor to refer matters of significant structural cracking to a Chartered Structural Engineer and they will recommend a report by such an expert.

A brief description of subsidence

Subsidence is the general term used for “sinking” of the soil and the consequent movement and cracking of the building on that sinking soil mass. Whilst it might sound rather dramatic, the reality is that in most cases that amount of subsidence is measured in a few millimetres rather than centimetres or inches so damage is normally fairly modest structurally.

Subsidence causes vary, depending on many factors as mentioned above but in 90% of cases in London and the Home Counties it is usually when a period house has shallow foundations resting on a shrinkable clay subsoil AND with medium to large trees nearby. There are exceptions however, which will be discussed in more detail in a subsequent paper.

A clay soil is a bit like a “blu tack” or plasticine and is mouldable by hand so is not very strong compared with bedrock, sands or gravels. Specifically, the clay comprises a large volume of tiny water molecules and it is the varying water content from one season to the next, or when sucked dry by tree roots, that causes a reduction in volume of that soil mass. This results in a downward movement of the soil together with that part of the building resting upon it.

In loose granular soils like sand, silts and fine gravel, if nearby drains are broken and fractured, the soil can fall into the drain pipes and be washed away, causing weaknesses in the soil beneath the foundations; a further but less common cause of subsidence.

Subsidence occurs regardless of any weight loading. For example, the ground under a garden path or lightweight conservatory might subside in periods of drought.

Mining subsidence and underground water course erosion of chalk and limestone rock, found elsewhere in the UK, is very unusual in the Home Counties due to the differing geology and is not dealt with in this article.

Settlement versus Subsidence

Subsidence is not the same as settlement and the distinction is very important.

Briefly, subsidence occurs when the soil mass below a house moves downwards of its own accord eg in dry summers, whereas settlement only occurs when weight loading is applied and squashes the soil downwards eg when building an extension or raising a house higher.

Settlement commonly occurred in most pre Second World War housing because foundation design was not understood and whilst many house were and are still very robust above ground, they have little or no foundations as we would know then today.

As a general rule of thumb most foundations in homes built before 1920 were typically the most shallow at some 20 to 40 cm below ground level. Post 1920s until the 1960s many house were founded at about 60cm deep

Only after the drought of 1976 did foundations routinely extend to 1m below ground and deeper in some instances, as the construction industry learnt of the dangers of tree roots causing subsidence.

In extreme cases when building near very large oak or poplar trees, new foundations were on occasions built to 2.5m deep or alternatively are now commonly supported on concrete stilts called piles instead, which extend much deeper into the soil.

Settlement takes place fairly immediately on granular soils like sand and gravel, usually within a year or so, and within the first five years or so on clay soils. For period houses, settlement is therefore by definition historic.

Settlement only rarely occurs in modern extensions and new houses due to the demands of modern building Regulations and design office Eurocodes used by Structural Engineering designers for their calculations of beams and foundation sizes.

We do see some settlement in poorly constructed ground bearing slabs for extensions when the ground is not sufficiently well compacted.

All this explains the importance of obtaining proper “design” advice from a structural engineer together with achieving Building Regulations Approval, including the completion certificate when works are completed.

What you should do if you think you have subsidence

There are two general options but these might be influenced by a number of factors mentioned further below;

1. Notify your insurance company and hope they deal with it professionally.
2. Obtain an independent report from a Chartered Structural Engineer

Historically subsidence claims were dealt with via a panel of independent Structural Engineers overseen by Loss Adjusters on behalf of Insurance Companies. This has all changed and almost all cases are now dealt with “in house” by Insurance Companies and “term contractors” with mixed success as far as the homeowner is concerned.

As a house owner your probably have subsidence insurance as part of your building insurance policy. If you are a leaseholder, the insurance is probably via the freeholder.

Most insurance policies have an excess to pay upwards of £1500.

If you start with your insurance company you will not incur any initial costs but may or may not receive the correct technical advice as a Chartered Structural Engineer will not be involved in most instances.

Alternatively, you might initially seek the advice of an independent Chartered Structural Engineer with professional fee costs of the order of £1500, paid by yourself.

Some insurance companies now ask for a structural inspection report from a Chartered Structural Engineer before they will visit or deal with a claim in order to establish whether there is likely to be a subsidence case to deal with or not.

Note not any damage or any cracks or movement are automatically dealt with by insurance companies. They do not deal with either pre-existing, pre-policy inception date, damage nor maintenance and wear and tear issues.

You are obliged to notify your insurers if your property suffers significant damage but you may or may not elect to make a formal claim in order for them to consider covering repair costs. Some people would rather fund modest repair costs and maintain a “ clean” insurance policy much like a “no claims” car insurance policy. This is particularly useful if you are intending to sell the property in the near future as a prospective buyer might be put off by news of recent insurance claims. In our experience solicitors advising buyers are very nervous about recent insurance claims.

A good independent Chartered Structural Engineers report will make clear whether you have a current subsidence issue or not and what order of costs might be involved in dealing with repairs. This will hopefully help inform you whether to make a formal insurance claim or not.

What insurance claims and repairs do NOT do, however, is improve the property nor prevent similar damage occurring again in the future – insurance is about repairs rather than improvement. For example, the repair of cracks does not mean they will not reoccur one day. If, however, an offending tree can be easily removed or reduced in size this will reduce the risk of a future re-occurrence at marginal cost.

In the past properties were frequently underpinned, deeper foundations were created by pouring concrete under the existing foundations, as part of a repair but this rarely occurs today as it is deemed an improvement to the house and is not often needed solely to repair damaged foundations. Only in very rare circumstances where a very large tree on neighbouring land or with a tree protection order placed upon it and where year on year recurrent damage is eminently foreseeable, might underpinning be considered as part of a repair.

Normal repairs

Without going into detail now, in the majority of cases, cracks and damaged decoration are easily repaired and rooms redecorated. Routine tree pruning or pollarding together with any drainage repairs are commonplace.

Cracks masonry must be repaired properly with either resin (for fine cracks) or Cementitious grout for larger cracks. In instances where   a wall has been substantially weakened and would benefit from additional tensile strength, some cracks are reinforced by stainless steel helibar rod reinforcement but only when specified by the structural engineer.

Repairs must be carried out by specialist repair contractors and approved helibar installers not general tradesman or builders ideally.

Most crack repairs are relatively inexpensive, certainly in comparison with very high property prices. Normally, one or two cracks can be repaired for a £1,000 to £2,000 and some 20 or 30 cracks dotted around a large house could be repaired for less than £20,000 excluding redecorations, so the figures are by no means astronomical. Smaller cracks can be repaired within the normal insurance policy excess, typically £1500 and whilst insurance companies should always be notified of damage, there is often no financial reason to make an Insurance claim.

Reflections

We are frequently surprised that lending institutions are so risk averse, at the slightest mention of subsidence, given how rare expensive underpinning is and how marginal most crack repairs are.

Most of us know, anecdotally, that many of London’s older housing stock has had some sort of minor subsidence in the past and either an insurance claim is on record or there are a few cracks in need of repair from time to time.

Unfortunately there is a big disconnect between the perception of subsidence and what it really means and this creates significant tensions during the buying and selling process which is related more to public perception and lending or insuring implications rather than issues of structural engineering.

Our role as Chartered Structural Engineers in this arena is therefore as much about human perceptions and expectations as it is about structural engineering. A good Structural Engineer can hopefully help you with both.

Conclusions

This article has introduced the broad subject of subsidence and settlement and what it means for you whether owning, buying or selling property. It provides guidance on what you might do if you think you have subsidence and gives food for thought regarding the issues surrounding selling a property at this time.

A future article will shortly provide some information and guidance on what subsidence cracks might look like and when you might become concerned.

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