To begin with, it is important to recognise our level of specialisation and expertise. While a Surveyor possesses a general knowledge of various matters, similar to that of a GP Doctor, we as Chartered Structural Engineers have dedicated our studies and training to structural engineering. This includes areas such as stresses and strains, building construction, soil geology, and foundation design.

We conduct regular inspections of structural defects, and given that UK and London housing stock often utilise uniform construction materials and foundation types, we are well versed in identifying likely building defects and determining their probable causes.

Here are some key aspects of our process:

1. Client instructions: We first understand the concerns and context of the client, whether they are buying, selling, need an insurance assessment or just have general structural concerns. The report’s purpose is crucial, whether for peace of mind or meeting mortgage requirements. Issues might be localised, like a crack in a bay window, or more general signs of movement and subsidence. Or lack of building regulation approvals

2. Pre-site research: Each property is different and requires careful pre-visit planning, including travel logistics and key arrangements, which can impact time and cost. Especially fitting in with the owners or occupiers and accessing keys for the property. We consider access, health and safety concerns, and other specific site issues, particularly in derelict properties.

3. Geology maps: Geology maps are essential as we assess soil types, which influence subsidence patterns in relation to trees, drains, and watercourses. We focus on clay soils, when present, for tree-related subsidence risks such as location and size, and sand and gravel soils for potential drainage issues. Particularly as cracked drains can cause the softening or erosion of the soil supporting the foundations.

4. Review of maps and photographs: Google Maps and historical photographs provide insights into property type, architecture, and historical defects. These images assist us in understanding the property’s structural history and surroundings.

5. Meeting the agent or owners/occupants: We introduce ourselves on site, explain the process and duration, and gather historical information about the property’s condition and repairs. Diplomacy is crucial since property owners are often unaware of our specific role, especially if concerns have already been flagged by another surveyor.

6. The survey:

In general

The starting point for our visual inspections, supported by binoculars, is to view the property from some distance away. From this view, point we can assess sloping windows or brickwork indicating settlement.

We analyse tree and drain locations concerning any cracks. We then view the property from the inside conducting a detailed walkthrough where we assess the general layout and condition. It will also tell us whether any major walls have been removed that might contribute to our assessment together with the location of the staircase, in the case of high flank and end of terrace walls, where leaning or bulging walls might be an issue.

In detail

The General Movement Report assesses each primary loadbearing wall, initially from the exterior followed by the interior, to evaluate its alignment, level, and vertical integrity, noting any substantial leaning or bulging. Each wall is inspected for significant cracks in the brickwork or pointing that could indicate structural movement. These cracks appear in both the interior and exterior at the same location, penetrating the full thickness of the wall and measuring approximately 2-3mm or more. Smaller or randomly oriented cracks are generally not a concern. Crack measurement gauges are employed when precise crack widths need to be measured and compared between the interior and exterior.

We use a spirit level to check vertical and horizontal alignment of brickwork, door and window fills where appropriate. For example, where suspected long term settlement or subsidence had taken place. These confirm our visual impressions gained over many years of experience. It’s important to be aware that most period houses have a degree of long-term distortion which would have occurred long ago, so this does not necessarily matter unless there are also indicators of recent movement. This is where our diagnosis of crack patterns becomes very important.

We check wall-to-wall and wall to ceiling junctions for signs of bulging or leaning of external walls but it’s worth pointing out that these walls are rarely mechanically connected together so some plaster cracking usually occurs in such areas.

7. Records: Comprehensive notes, photographs, and videos are recorded during the survey process for report preparation and as a reference but are not included in the client report.

8. Client feedback: Clients receive immediate feedback through a phone call post-survey, providing an early indication of findings, which aids in understanding the forthcoming detailed report.

9. Reporting: Our General Movement Reports are detailed documents, typically 15-20 pages long, including a summary, client brief confirmation, site observations, findings discussion, conclusions, and tailored recommendations.

10. Cost estimates: We provide general guidance on repair costs to inform client decisions, emphasising these are not formal quotes or specifications.

11. Builder Recommendations: We can suggest specialists for necessary repairs but do not supervise repair work.

12. Telephone Support: We provide follow-up phone support within two working days post-report to address any further questions.

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This principle extends to structural engineers drafting reports and surveyors conducting routine domestic house surveys, even though these activities are separate from the design and specification of building works. If a property survey is conducted by someone lacking competence, errors will go unnoticed, and incorrect advice may be given. This could lead to clients purchasing unsuitable properties, especially if costly repairs are later needed that were not identified in the pre-purchase survey.

A recurring issue among structural engineers involves non-qualified individuals performing design calculations, as well as substandard reports being produced by junior staff and unchartered engineers. Although the consequences of poor reporting are generally less severe than calculation errors that could compromise a building’s structural integrity, both highlight the critical importance of competence.

Building a safer future

Competence was the central theme of Dame Judith Hackitt’s “Building a Safer Future” report, which has become something of a manifesto for building safety information. The Building Safety Act 2022 was enacted following the Grenfell findings, alongside the publication of British Standard BS 8670-1 2024, which establishes a competence framework for building safety. This framework aims to ensure major design projects employ individuals with the relevant experience and competence, fostering seamless information sharing and responsibility among the various professions involved in building design or refurbishment.

While inspecting buildings and producing structural engineering reports for residential properties is distinct, the same learning points apply. Clients should rightfully expect that those conducting such reports demonstrate both experience and competence.

What you need to achieve true competence

Competence is understood to arise from a blend of four fundamental elements:

1. A) KNOWLEDGE
2. B) SKILLS
3. C) EXPERIENCE
4. D) BEHAVIOUR

For someone to achieve true competence, they must possess the right balance of skills, knowledge, and experience, paired with suitable behaviour. The British Standard BS 8670:2024 frequently references these elements, abbreviated as SKEB.

Competence must pertain to the role of the individual, whether undertaking a site inspection to diagnose a structural issue, writing reports or dealing with clients regarding commercial and financial issues.

When conducting a structural engineers report site inspection to diagnose concerns like subsidence or roof spread, it is vital that the task be undertaken by a COMPETENT professional, as pre-purchase reports often necessitate immediate judgment. Delays for further inquiry, testing, or monitoring are impractical. Therefore, the author strongly recommends that such inspections and reports be carried out by thoroughly qualified Chartered Structural Engineers, capable of making accurate, informed decisions on the spot.

As outlined by the Engineering Council in the 2020 UK Standard for Professional Engineering Competence and Commitment (UK-SPEC) 4th Edition, various membership grades correspond to distinct levels of activity and function.

Table 1 of the Engineering Council Guidance clearly differentiates the expected competence between Engineering Technicians, Incorporated Engineers (IEng), and Chartered Engineers (CEng).

Moreover, the Institution of Structural Engineers’ professional Code of Conduct stipulates that ‘members shall undertake only those tasks and accept only those appointments for which they are competent’.

In summary

The consequences of the Grenfell fire tragedy forced the entire construction industry to take a close look at itself leading to noticeable improvements across the sector.

In particular, it is not clear that only those with demonstrable skills and competences should undertake the design of a particular building suited to their skills. This principle should extend to all professional services, including Structural Engineers Reports, especially at the point of sale. Limited time is often available to inspect and report on findings, and critical life decisions, such as whether to purchase an expensive home, hinge on the quality of this advice.

It is therefore essential for clients to engage only chartered Structural Engineers with proven competence in the specialised field of residential surveys and reports.

Image by monikazoran from Pixabay

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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.

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The legal enquiries conducted by the conveyancing solicitor will determine if any Building Regulations or Town Planning consents are required. This process depends on the accuracy of the information provided by the vendor and the findings of the buyer’s RICS survey, if commissioned. Buyers are generally encouraged to commission at least a level-2 RICS survey, particularly considering a level-3 survey for larger, older, or unique properties.

A competent surveyor will identify any Building Regulations issues, and most buyers, with their solicitor’s assistance, will review the surveyor’s report and take note of any necessary specialised reports.

Estate agents play a pivotal role in nearly all residential property transactions, overseeing the entire process. An experienced agent understands the position of both sellers and buyers, as well as the roles of solicitors and others in the transaction. They are adept at identifying and navigating issues that might impede a sale, which could affect their clients’ interests, their own sales and commission potential, and their professional reputation.

Potential issues include missing documentation for alterations, such as town planning or building regulations approvals, landlords’ consent for structural changes in leasehold properties, and defective RICS surveys. An effective agent proactively addresses these foreseeable challenges to ensure a smooth transaction.

When it comes the subject of structural engineering and evaluating a property’s condition at the point of sale, we have encountered several common issues that may be informative for estate agents refining their skills or seeking a refresher. A Structural Engineer’s Report may be necessary in certain situations, which can significantly facilitate the sales process if addressed early.

Circumstances that might require a Structural Engineer’s Report include:

1. Presence of cracks or structural movement

2. Instances of previous underpinning or subsidence insurance claims

3. Surveys that have failed to meet requirements, resulting in mortgage or buyer concerns

4. Past modifications made without proper Building Regulations Approval

5. Flats with alterations, such as wall removals, carried out without the landlord’s consent.

Our useful advice regarding the topic above includes the following:

a) In general

When it is highly likely that a buyer will request a Structural Engineer’s Report, due to concerns such as cracks, movement, underpinning history, or changes to Building Regulations, it is advisable for the seller to proactively obtain this report.

Based on our experience, it is beneficial for the seller to commission a Structural Engineer’s Report from a Chartered Structural Engineer who is well qualified and experienced in residential properties. Such a report should address the issues in a practical manner that aligns with the buying and selling process. This report can provide the owner with valuable information on necessary repairs and estimated costs.

Additionally, it can be shared with prospective buyers on a transparent basis or transferred to them, keeping in mind that there may be extra fees associated with this transfer due to the additional responsibility and effort required to alter the report’s context.

b) Notable cracks, sloping floors or doors

During valuations or initial viewings, if you notice a significant crack near the front door or in an equally prominent place, it should not be disregarded. The buyer’s surveyor will undoubtedly notice it and may request a report from a structural engineer, which might be required for mortgage approval or simply to reassure the buyer.

c) Past underpinning or subsidence insurance claims

If your initial vendor questionnaire or conversations reveal previous underpinning or a subsidence claim, it is likely to raise concerns for both the buyer and their potential mortgage and insurance providers. Despite the apprehension these terms evoke, particularly since unnecessary underpinning was common before the 2000s, an underpinned house is now more robust than before and often more so than similar properties. Commissioning an early report from an experienced Chartered Structural Engineer can greatly help to reassure all parties involved.

d) Failed surveys, mortgage or buyer survey concerns

Concerns from mortgage or buyer surveys often lead to the need for a Structural Engineer Report. These are typically prompted by a Surveyor’s observations. For instance, a valuation survey for mortgage approval might necessitate a Structural Engineers Report. Alternatively, a Homebuyer’s or full Building Survey may suggest a Structural Report for the buyer’s reassurance. As an estate agent, obtaining feedback from the Surveyor’s report enables you to promptly recommend a Structural Engineer Report, potentially expediting the process. If the property is in poor condition or if there are existing cracks and a history of structural movement, anticipating the need for this report can facilitate a smoother transaction.

e) Previous alterations without Building Regulations approval

One of the most common issues involves previous structural alterations made without proper documentation, such as the approval of plans and the issuance of a completion certificate through Building Regulations. This situation often arises with loft conversions, extensions, or the removal of walls or chimney breasts.

Estate agents should be aware that structural engineers can carry out a visual inspection. If alterations were completed many years ago, these structural inspections often indicate whether the modifications have endured over time. Conversely, if changes were made in recent years, it is challenging to determine their safety and durability due to the lack of a proven track record.

During a property sale, only a visual structural inspection and reporting are conducted. Structural engineers do not dismantle the building or perform any form of retrospective calculations. While these steps are possible if requested by the vendor, they are time-consuming, more costly, and seldom found to be necessary.

f) Flats without landlord’s consent for structural changes

In cases where structural changes, such as wall removals, were made without the landlord’s consent, a retrospective assessment may be necessary, similar to those conducted for non-compliance with Building Regulations. Solicitors representing buyers will likely advise their clients to obtain such assessments when there is no evidence of the landlord’s consent or adherence to Building Regulations, for clear reasons related to professional diligence.

Conclusions

Estate agents play a crucial role in identifying the need for specialists, such as structural engineers, to facilitate smooth property transactions. Proactively addressing this need can save considerable time, reassure buyers, and help prevent sales from collapsing due to unforeseen issues.

Ensuring that the engineer is a Chartered Structural Engineer (C Eng, MIStructE) rather than a partially qualified graduate is essential. Such professionals possess the expertise to prepare concise, practical reports efficiently, without requiring extensive additional investigations.

When estate agents identify potential issues with consents or documentation, recommending that sellers obtain a structural report early can alleviate stress further down the line. These reports often provide the reassurance needed to keep cautious buyers from seeking alternative properties. An estate agent’s foresight in this regard can be invaluable in maintaining the transaction’s momentum.

Should there be any doubts about the necessity of these reports, a simple call to a local firm of Chartered Structural Engineers can provide clarity and guidance.

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Experienced estate agents anticipate and navigate various issues that may hinder a sale, which could affect both their clients’ interests and their own commissions and reputations. Such issues include missing documents for alterations or extensions, like town planning or building regulations. The absence of landlord consent for structural alterations in leasehold properties, and defective RICS surveys. A proactive agent can foresee these potential challenges, aiding in a smoother sales or purchase transaction.

With regards to structural engineering and property condition at the point of sale, we have practical experience with numerous issues that could benefit both estate agents learning their craft and seasoned professionals seeking a refresher.

Reasons a property might require a Structural Engineer’s Report include:

1. Cracks or structural movement
2. History of underpinning or insurance claims for subsidence
3. Concerns raised by failed surveys, whether mortgage or buyer-related
4. Previous alterations without Building Regulations Approval
5. Flats with structural changes made without landlord consent

Our helpful suggestions regarding the above points:

a) General points

If it is likely that a buyer will request a Structural Engineer’s Report due to issues such as cracks, movement, or a history of underpinning or unauthorised building work, it is advisable for the seller to proactively obtain this report. Experience shows that a report from a Chartered Structural Engineer, who is well-versed in residential property issues, can be immensely beneficial. This report not only informs the owner about necessary repairs and associated costs but can be openly provided to prospective buyers. It can even be assigned to them as a reliable reference, though this may incur additional fees to cover the changes in the report and additional responsibilities.

b) Cracks, sloping floors, or door issues

If, during a valuation or early viewing, you notice a significant crack near the front door or in any prominent location, do not ignore it. The buyer’s surveyor will undoubtedly spot it and might request a Structural Engineer’s Report to satisfy mortgage application requirements or to reassure the buyer.

c) Previous underpinning or insurance claims for subsidence

If your initial vendor questionnaire or discussions reveal previous underpinning or a subsidence claim, this is likely to raise concerns for both the buyer and their potential mortgage and building insurance providers. Despite these terms often causing alarm, in practice, they may not be problematic. Underpinning was quite commonly carried out prior to the 2000s, often unnecessarily. In fact, an underpinned house is now stronger than it was prior to underpinning and will compare very favourably to similar properties. In our experience, an early report from a seasoned Chartered Structural Engineer can often alleviate concerns for all parties involved.

d) Concerns arising from failed surveys, mortgages, or buyer surveys

Structural Engineers’ Reports are often requested due to issues identified by a surveyor. This could involve a valuation survey required for mortgage purposes, in which case a Structural Engineers’ Report may be necessary. Alternatively, it might stem from a buyer’s Homebuyer or full Building Survey, both of which might suggest obtaining a structural report for the buyer’s reassurance.

As an estate agent, obtaining feedback from the surveyor’s report allows you to recommend a structural report early, expediting the process. If the property is in poor condition, or there are visible cracks and a history of structural movement, anticipating the need for such a report early can facilitate a smoother transaction.

e) Previous alterations without building regulations approval

A common issue arises when prior structural changes have been made without the necessary documentation, such as the approval of plans through Building Regulations and a completion certificate. This scenario often involves loft conversions, extensions, or the removal of walls or chimney breasts.

Estate agents should be aware that structural engineers can conduct a visual inspection, similar to checking a car’s condition. When alterations were completed many years ago, we can generally ascertain that they have endured over time. However, if changes were made recently, it is more difficult to determine their long-term safety and stability, as insufficient time has passed.

During a property sale, structural engineers can only perform a visual inspection and provide a report, as we do not dismantle the building’s fabric or carry out retrospective calculations. Such an in-depth analysis could be arranged by the vendor, but it is time-consuming, costly, and, in our experience, often unnecessary.

f) Flats without landlord consent for structural changes

If any work, such as wall removal, was done without the landlord’s consent, a retrospective assessment can be carried out, similar to the procedure for non-compliance with Building Regulations. Solicitors representing buyers will likely advise obtaining these assessments when consent or compliance is missing, to ensure due diligence and professionalism.

Conclusions

The pivotal role of the Estate Agent positions the profession to anticipate the need for specialists, including Structural Engineers’ Reports. A proactive approach can save considerable time, boost buyer confidence, and maintain transactions that might otherwise collapse due to unforeseen stress.

It is important that the Engineer is a Chartered Structural Engineer (C Eng, MIStructE), not just a partly qualified Graduate Engineer. They should have experience in creating practical sale reports, with concise and quick responses, avoiding lengthy investigations or testing.

If the Estate Agent identifies any deficiencies in consents or documentation, recommending an early Structural Report can prevent future stress during the sale process. We have encountered numerous situations where such reports have reassured buyers, securing the sale for the vendor, as opposed to risking the buyer seeking other properties. Estate Agents must anticipate this need and act proactively. For any uncertainty about the necessity of reports, a call to a local firm of Chartered Structural Engineers can provide guidance.

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Pre-purchase Structural Engineers Reports are frequently called for during the sale of residential property on matters such as cracks, fears of subsidence or settlement or general structural problems noted but not diagnosed in a Chartered Surveyor’s report. These reports are primarily for mortgage purposes or RICS Level 1 or 2 Surveys.

The qualifications required for preparing reports by institutional lenders and building insurers can vary significantly. While Chartered Building Surveyors were once commonly tasked with this role, Chartered Structural Engineers are now often preferred. However, both lenders and property buyers often mistakenly believe that these inspections and reports are conducted by fully qualified, expert, and experienced Chartered Engineers.

Prospective clients often draw parallels with consultations involving top medical professionals, like an orthopaedic surgeon, who they expect to be highly qualified. They do not expect the patient, in our case, the property, to be evaluated by a junior doctor who merely discusses their findings with a senior colleague before the latter signs off on the prognosis.

For 35 years, my practice, SERL, has always used Chartered Engineers for such important pre-purchase reports, though this is not common. It often surprises prospective clients to learn that these structural inspections can be conducted by junior staff members, as long as a Chartered Engineer within the same organisation reviews and signs off the report. This process ensures the report meets lenders’ requirements if appropriate.

It is common for multiple staff members to be involved in the somewhat leisurely handling of “subsidence claims” for property owners and insurers. However, I argue that this approach is not appropriate for point-of-sale reports for the following key reasons:

a) Pre-purchase Inspections and reports are normally urgent and arise immediately prior to exchange of contract or at the eleventh hour when mortgage offers are urgent. They are “one offs” with little time for reflective thought or involving others.

b) Pre-purchase Inspection and reports are quite unlike Subsidence claims or general advice to owners since there is no practical prospect for investigations, monitoring of cracks or soil testing.

c) Reports require a lot of knowledge and expertise to determine likely the cause of structural issues with little time to “dig deeper”.

d) The financial and contractual importance of an expensive property purchase should be matched by the importance of the expertise and qualifications of those advising.

e) The need for a Structural Engineers Report has already been identified by a Chartered Surveyor so it now requires a more expert and experienced set of eyes than the Surveyor.

f) Third party Lenders and Insurance companies are relying on the same advice that we provide the prospective buyer, so they are entitled to assume it is an experienced and qualified opinion.

g) My practice, SERL, has encountered some truly shocking reports prepared by inadequately qualified individuals. These reports are rejected by lenders and insurers, damaging the reputation of our esteemed institution.

My proposal

I propose that such reports should only be carried out and signed by a fully qualified Chartered Engineer, not a graduate or technician engineer. This is normally a Chartered Structural Engineer with qualifications CEng MIStructE. Alternatively some Civil Engineers have relevant residential building experience so the qualification CEng MICE may be applicable where experience applies.

For the reasons set out above, and with no disrespect intended to less qualified Engineers, the pressures of time and the need for a “one off” structural inspection and report does not allow for a process of less qualified people carrying out inspections and the matter then being referred to a more senior person in the office for a signature.

Simon Pole BSc CEng FIStructE MICE MRICS MAE

Simon is a dedicated Chartered Structural Engineer. He actively conducts daily Structural Engineers Reports for clients covering the Greater London area. He is extensively involved in numerous professional interest groups and has lectured widely to Structural Engineers, Surveyors, and Party Wall professionals.

His voluntary contributions to the Institution of Structural Engineers include helping graduates prepare for their professional examinations and advising the professional conduct committee on matters within his expertise, as well as on general ethical and professional standards.

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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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