Reasons for contacting Structural Engineers Reports Ltd (SERL)

A prospective buyer of a terraced property contacted us following a failed mortgage survey. The valuation surveyor was concerned about various cracks inside and out, together with a more general history of movement.

N.B. Although this report was for a buyer, some twenty per cent of our enquiries are from owners who are either concerned about their property generally or, alternatively, are about to market their property for sale and wish to have a report which they can share with prospective buyers.

Summary

N.B. We always provide a one-page, easy-to-read summary at the beginning of each report.

We are satisfied that the property remains strong and shows no signs of any modern day movement. The various cracks noted were all considered historic and entirely normal for a period property more than one hundred years old.

The structural significance of the cracking can be conveyed to you numerically on a scale of one to ten, where one is minor and ten is severe. In this regard we would rate the cracks in this property at about two to three out of ten.

N.B. We often use a medical analogy and would in this instance describe the property as requiring a proverbial paracetamol rather than open heart surgery, open heart surgery being analogous to major underpinning or strengthening works.

Once the repairs have been carried out we would consider the property to be a normal lending and insuring risk.

N.B. When assessing the risk we consider the geology, proximity of trees and drains, etc.

Brief

We confirm your recent instructions in conjunction with your intended purchase of the above family terraced house.

You explained that your mortgage survey has highlighted cracking of some concern and the bank requires a chartered structural engineer’s report before considering the mortgage application. We further understand that the cracking is widespread inside and out.

Given the bank’s requirements you will need our general report, known as a General Structural Inspection, on all the main loadbearing walls inside and out. We have agreed to provide guidance regarding costing for repairs and can provide the names of specialist repair contractors.

N.B. Less frequently we provide a more localised report, known as a Specific Structural Inspection, where concerns are very limited such as for example a single crack in a single bay window.

We trust we have interpreted your brief correctly but please contact us immediately if not.

N.B. A formal report would include more details and would refer to guidance notes provided to clients prior to receiving confirmation to proceed with our inspection so clients are quite clear what we do and what our deliverables comprise.

Description of Property and Geology

The property is a very standard mid-terrace family dwelling house on two floors plus loft conversion.

The construction appears to comprise normal solid brick external walls with suspended upper timber floors and roof framing. Elevations are all yellow stock brickwork. The architectural style is typical of early 1900s construction.

The house layout is traditional with primary rooms in the forward part of the house between party walls and secondary rooms within the narrower but original rear projection adjoining the right hand party wall. There are no modern day extensions or significant changes to original room layouts.

The property occupies a fairly level site. Our geological mapping records indicate London Clay subsoil. There is a large London plane tree close to the front left-hand side of the property within five metres. The tree is some fifteen metres tall. The drains appear to pass beneath the property from the rear towards the front. The house is in good order decoratively but has not been well maintained externally. An RICS Surveyor will comment on this in more detail.

Site Observations

Background context

Most of our detective work is carried out externally, since it is the bricks which form the main skeleton of the house, together with just one or two internal loadbearing walls.

We are mainly concerned with any cracks of a “structural Engineering nature” generally described as those cracks which occur on both sides of a loadbearing wall, eg inside and out in the case of an external wall AND where crack widths exceed about 3mm. This acknowledges that almost all building materials together with the soil mass, expands and contracts from time to time causing normal/ seasonal movements which do not compromise the structural integrity of a property.

In detail

The property exhibits a pronounced slope from right to left away from the front door and towards the bay window and the left-hand party wall.

There are various cracks dotted around the front elevation, typically between 1‑3 mm wide. In particular there is vertical cracking where the bay window abuts the main front elevation of the property, but all of this cracking is extremely discoloured and clearly of long standing.

Our internal observations note the decoration is old, at least ten or fifteen years in our estimation. Crucially there is no corresponding cracking internally, which confirms our suspicion that the cracking is long-standing and dormant.

The various brick arches over first floor bedroom windows are in good order.

The brickwork and pointing generally is also sound and your RICS surveyor will comment on all of this in more detail from a maintenance and general repair point of view.

At the rear of the property there is minor cracking where the front and rear halves of the property adjoin, which is very common. Internally there is an old crack in this location but this too shows no signs of any modern movement.

Internal floors slope from right to left, consistent with the cracking noted externally both within the front part of the house and the rear projection.

N.B. A formal report would include more detail that this.

Conclusions

See summary at the beginning of the report for an easy-to-read précis.

The property shows normal signs of historic settlement, from right to left, commensurate with the age of the property. We suspect that most of this early age settlement occurred soon after construction as the weight of the house squashed into the soft soil.

There has clearly been a minor to moderate dose of subsidence in the medium term past, approximately some twenty years ago, but crucially there is no sign of any ongoing movement.

The cracks require a routine resin repair and we estimate costs of approximately £3,000-£5,000 in this regard. We can recommend appropriate repair contractors for this work, which ideally should not be undertaken by a general builder. We recommend that you allow for testing of and minor repairs to the drains as part of your early planned maintenance.

Ideally the Local Authority would be encouraged to reduce the height of the tree, given that it is far too large for the urban environment.

It is obviously important that you maintain building insurance, and specifically subsidence cover, for any period house, particularly those on London Clay soils and fairly near large trees. It is however the nature of owning a period property that there is always a residual subsidence risk, but fortunately there is no sign of any recent movement here within the last twenty years or so.

Report signed by Chartered Structural Engineer.

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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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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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An owner contacted SERL, having found us via an online web search and based on our good Google reviews.

The client sought our expertise in structural engineers’ reports, especially within the South-West London area.

SERL’s structural reporting service

In response to the client’s requirements our qualified Chartered Structural Engineer recommended a General Structural Inspection (GSI) report.

SERL offers two types of structural reports:

1)       A localised, specific, and limited Specific Structural Inspection (SSI) report or a Structural Engineers Defect Report.

2)       A broader General Structural Inspection Report (GSI) or Structural Engineers General Movement Report which focuses only on matters of cracking and movement.

Our Chartered Structural Engineer’s report for the South West London property

The owner, who purchased the house the previous year, had become increasingly aware of various internal cracks in numerous rooms and was concerned they might indicate serious issues. Before proceeding with a major refurbishment, the owner wished to understand the significance of these cracks.

This property is a typical 1920s semi-detached house, constructed with solid brick walls, suspended timber floors, and roof framing.

Situated on the well-known London Clay geology, the property is near several large trees, especially at the rear.

SERL’s findings

The living room, master bedroom, and stairwell exhibited several cracks. However, we assured the owner they were merely superficial plaster imperfections, nothing that was structurally concerning. Our examination of the building’s exterior found no evidence of any contemporary structural movement.

SERL’s conclusions and recommendations

We were satisfied that none of the cracking was serious which relieved the owner and allowed them to move ahead and plan the internal refurbishment without concern.

We did make various recommendations with regard to removing a tree in the front garden and pruning trees at the rear, but because the latter were on neighbouring land addressing this issue always proves more complicated.

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A prospective buyer contacted SERL based on recommendations from their valuation surveyor. They needed a report to address the concerns of their mortgage surveyor, who identified structural issues associated with both general external and internal cracking.

The surveyor had endorsed SERL Structural Engineers Reports as a reputable, independent, and highly experienced structural engineering firm practising in the Sheen and Richmond area of South West London.

SERL’s structural reporting service

In response to the client’s requirements our qualified Chartered Structural Engineer recommended a General Structural Inspection (GSI) report.

SERL offers two types of structural reports:

1)       A localised, specific, and limited Specific Structural Inspection (SSI) report or a Structural Engineers Defect Report.

2)       A broader General Structural Inspection Report (GSI) or Structural Engineers General Movement Report which focuses only on matters of cracking and movement.

Our Chartered Structural Engineer’s report for the South West London property

The property is a right-hand semi-detached family home, likely built in the early 1900s based on its architectural style. It is situated on a relatively flat site, which our geological mapping suggests is probably Kempton Park Gravel.

The interior decoration is in extremely poor condition and appears to have been neglected for about thirty to forty years. Consequently, there are more internal cracks than one might typically expect.

SERL’s findings

The rear elevation of the property exhibited one significant crack that will require a thorough resin repair as part of regular maintenance. However, this issue does not affect our assessment of the property’s value or risk from a purchase or loan perspective.

Overall, the alignment and stability of the house is good, and better than many other properties we survey. This is evident in the straightness of the brickwork and the alignment of door and window sills.

Occasional spirit level checks indicated minor undulations in the alignment of the window sills and brickwork, which are within acceptable standards, especially for a property of this age.

SERL’s conclusions and recommendations

We were confident that the structural issues could easily be repaired for a few hundred pounds, which would allow the purchase to proceed.

We were able to provide a positive report to the client, who was pleased with our advice and guidance, and we expect that the mortgage company was able to approve the loan.

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Introducing Certificates of Structural Adequacy or COSA for short

This article explores the topic of Certificates of Structural Adequacy (COSA) within the context of buying and selling a residential property. Specifically, how they relate to a Structural Engineers Report for a buyer or, on occasion, a seller.

Certificates of Structural Adequacy (COSA) were established by the Institution of Structural Engineers in 2000. These certificates are important where a property has either been underpinned or had various structural cracks repaired within the last 20 years. See background below.

A COSA is NOT a form of Guarantee or Warranty and is often misunderstood. It is actually a concise, single-page document summarising relevant events, associated documents, company details, and a list of documentation. See below.

Increasingly, COSAs are requested by buyers’ solicitors, lenders, insurance companies, and surveyors before purchasing a property. See below.

What is a Certificate of Structural Adequacy and what it excludes

A Certificate of Structural Adequacy typically consists of a one-page summary of a major insurance claim related to subsidence. This may involve underpinning and/or significant superstructure crack repairs. Prepared by the lead consultant, the document summarises the entire process from start to finish, including initial reporting, investigations such as soil testing and crack monitoring, as well as the eventual design, specification, and site inspection of the repairs.

Since about 2020, there has been an increasing trend in the request for Certificates of Structural Adequacy during the pre-purchase Structural Engineers Report process. This typically occurs when evaluating cracking, movement issues, or providing advice on potential structural concerns during property transactions, regardless of previous occurrences such as subsidence or underpinning.

At SERL POLE, we issue these certificates clearly outlining their limitations, ensuring that clients fully understand them.

Defining what a COSA is NOT

Crucially the Certificate of Structural Adequacy (COSA) is neither a guarantee nor a warranty. It does not substitute for the guarantee from specialist underpinning or repair contractors, which may still be valid or might have expired. The COSA does not replace the need for a comprehensive Structural Engineer’s Report and can only be issued alongside such a report. Additionally, if the report concludes that the property is not “structurally adequate,” the COSA cannot be issued.

A COSA serves as a summary of the one off visual inspection and issue of a Structural Engineers Report, if that is the extent of the engineers’ evaluation. This excludes any intrusive investigation’s, crack monitoring, or similar activities, which are impractical during the sale process due to time constraints.

A COSA is a useful summary for those who prefer a concise report and do not wish to read the “small print” and the title can convey reassurance and confidence in the findings. This simplicity is likely why solicitors and lenders appreciate the concept.

This additional value of the Certification process does incur a commercial fee as it requires significant professional time and resources to explain the details to all parties involved. It is an extra service over and above our standard structural engineering reports.

It is important for SERL to clarify that the Certificate itself does not confer any contractual obligations beyond what is detailed in the written report, with which it should be read in conjunction. All our professional opinions are included within the formal report, which should be sufficient for most clients without necessitating a Certificate. Nevertheless, demand for COSA Certificates is rising due to the reasons outlined.

Should you have a Certificate of Structural Adequacy?

There is not a simple answer to this question. However, a COSA is becoming increasingly popular particularly amongst those selling their home because they add value to the vendors information pack providing reassurance to the buyer if the property appears sound.

Buyers sometimes obtain a COSA for similar reassurance, however, they are more frequently instructed to do so by their prospective lender or building insurer or via their surveyor.

We advise all our clients to carefully consider the limitations of such a Certificate as they do not provide any guarantee or warranty as detailed in this article.

Background

Since the turn of the millennium, Certificates of Structural Adequacy have been integral to the underpinning and building insurance sector. At that time, the collaboration between the Institution of Structural Engineers and a multi-party group, from the insurance and underpinning industry, determined that major subsidence claims should be summarised by the supervising engineer or loss adjuster.

Certificates of Structural Adequacy (COSA’s) were commonly issued following the underpinning of properties suffering from subsidence and they provided a useful resume of the lengthy Insurance claims process from investigation, design, specification and supervision of repairs.

COSA’s were not generally used by the wider construction or building industry.

COSA’s were not used by Surveyors and Structural Engineers who were not involved in the investigation, specification and supervision of building works.

COSA’s were not used, until very recently, by Structural Engineers carrying out a pre-purchase Structural Engineers Reports, where a one off opinion has been provided but with little or no knowledge of the subsidence history of a property.

The COSA has primarily been used in the insurance industry for procuring subsidence repairs. This involves a series of well-established, detailed procedures to investigate causes and implement suitable remedial actions, requiring the input and expertise of property professionals. Many experts and trades people contribute, including consulting engineers, geologists, arboriculturists, drainage experts, crack monitoring specialists, underpinning professionals, and general contractors. The whole process can often exceed a year. The need for a lead consultant to efficiently summarise the scope, parties involved, and actions taken in one succinct document led to the creation of the COSA in the late 1990s.

The COSA has not replace the professional responsibility of the parties involved and each service provider remains responsible for their advice according to their normal terms of client instructions and terms of business, also backed by their professional indemnity insurance. The specialist underpinning contractors normally provide a 10 year guarantee for their own works.

Today’s Certificate of Structural Adequacy

Since 2020, SERL POLE has noted that institutional lenders, insurance companies, and certain conveyancing solicitors frequently request a Certificate of Structural Adequacy (COSA) for any property purchase. This is regardless of whether there is a history of subsidence or underpinning.

From the above it is immediately clear that this was not the intention of the COSA and there is much misunderstanding even within the professions, regarding its appropriateness.

The limitations of a pre-purchase survey of any sort when the buyer or client is not the owner of the property, time and money constraints, together with all manner of practical implications, mean that it will never be possible to dig holes, test the soil, monitor the cracks for a year, and produce a report which states the property is fine, or structurally adequate.

As Chartered Structural Engineers we are able to assess the strength and stability of a property through a one-off, non-invasive inspection and provide their professional opinion. If a property is deemed “Structurally Adequate,” we will say so. Should the property need clear repairs without further investigations, we outline these in general terms and can confirm “Structural Adequacy” conditional upon such repairs.

By separate agreement beyond the visit and report fee, we can issue a Certificate of Structural Adequacy, provided the client acknowledges its limitations as outlined above. This certificate is not a guarantee or warranty but a summary of the report, with certain convenience and commercial advantages.

Surveyors, Banks and Lenders health warning

We would ask other property professionals to be fully aware of what a COSA is and is not, since they are often called for by lenders and Insurers during the pre-purchase process where RICS Surveyors Reports have recommended a Structural Engineers Report on behalf of the buyer.

It is essential for all parties to understand that when advising a buyer, the structural engineer’s role is limited to a single visit and report. The engineer cannot conduct detailed investigations into structural defects, such as monitoring cracks or testing soil, due to pre-purchase time constraints and because the buyer, not owning the property, is not technically the engineer’s client. As a result, the engineer cannot risk damaging the vendor’s property or create a conflict of interest by serving both buyer and vendor. Some lenders mistakenly request a “Certificate,” believing it provides insurance, indemnity, or warranty, when in fact, it does not exist.

Further Clarification and helpline

If readers of any status whether buying or selling or fellow professionals have any questions regarding this article, we will be very pleased to speak to you, so do not hesitate to call Structural Engineers Reports Limited on 020 8161 9900.

References

1. Subsidence by Institution of Structural Engineers published November 2023.

2. Subsidence of Low Rise Buildings second edition August 2000 Institution of Structural   Engineers

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The removal of chimney breasts is a common modification in family homes, but it is often not executed properly, raising concerns for lenders, surveyors, and structural engineers. They are typically removed to create additional space in a room or hallway as they can obstruct modern open-plan living and affect bedroom layouts or wardrobe storage. Removing them in narrower rear projections or extensions can increase the usable space in what might otherwise be a small room.

Chimney breasts are normally kept within the loft space to support the stack above the roofline, preventing costly roof repairs. Unless the loft is undergoing a conversion, keeping them in the loft does not affect the layout of the rooms below.

When chimney breasts are removed on the ground floor, they are often retained on the first floor to preserve period fireplace features in bedrooms or where they don’t disrupt the room’s layout. In period buildings with separate flats, the chimney breast can only be removed from within the specific flat, leaving other flats unaffected.

Chimney breasts were often removed years ago, particularly from the 1970s onwards, when fireplaces became obsolete. At that time, minor building work was done without the strict oversight of today’s Building Regulations, and fewer inquiries were made by prospective buyers, surveyors, and lenders.

Today, any structural alteration affecting health and safety must be carried out professionally and comply with Building Regulations, complete with certification and proof. This requirement also applies to historical alterations made before the current ownership of the property.

Chimney breast structures

Chimney breasts are simple brick structures designed and built to enclose flues for fires, such as those that used coal. These were often constructed using low-quality reject bricks, unsuitable for external use due to poor visual and structural characteristics.

Typically, chimney breasts were added after the construction of the flank or party wall, with minimal or no mechanical bonding (known as toothing in) between the chimney breast and the wall.

In some cases, flues were integrated within or alongside the thickness of a party wall, sometimes in conjunction with the neighbouring property, resulting in chimney breasts that do not project too far into the room.

Given the considerable weight of bricks, almost akin to concrete, proper support is essential for any unsupported brickwork. Additionally, chimney breast bricks have often endured years of exposure to fire, making them dry, brittle, and susceptible to degradation. The party wall behind the flue is also compromised by fire exposure, undermining its structural integrity.

What some builders do or used to do

Historically, builders often removed chimney breasts without providing adequate support to the remaining stack, posing potentially significant dangers. There have been rare cases where a chimney stack collapsed into the bedroom below during the night. Fortunately, no one was injured, but the risk of fatality was significant.

Builders for some time have relied on the practice of toothing in bricks from the chimney flue into party or flank walls, known as corbelling. This technique is often inconsistent and sometimes absent, with vertical joints used instead. When toothing is well-executed and neighbouring flues are solid, the chimney might remain stable for years. However, this stability is often due to chance, as these decisions are typically made without consulting qualified engineers.

As an interim, some builders have employed makeshift support methods for removed chimneys. This could be in the form of additional brick or stone corbelling built into the wall, or by using industry-known “gallows brackets.” These brackets are triangular frameworks similar to shelf brackets and rely on all important bolts fixed securely to a solid wall top and bottom.

Gallows brackets present a challenge because they depend heavily on the top bolt, which can be prone to pulling out from the solid wall, a condition engineers refer to as tension. While bricks are strong when compressed (pushed), they are notably weaker when pulled apart (in tension). This is particularly the case when the brickwork is of poor quality or involves burnt bricks.

Between approximately 1970 and 1990, gallows brackets were widely accepted by Building Control Authorities, however few authorities permit them today. See below.

Survey Issues

Surveyors for banks and buyers are understandably concerned when they encounter a removed chimney stack with inadequate support. In some cases, a gallows bracket might be present in the loft. But if the chimney breast is removed on the lower floor and not on the upper, it is highly likely that there is no support in the first-floor joist area between the floorboards and the ground floor ceiling.

Often, neither the Surveyor or the Structural Engineer can observe the structure because it is concealed below the floor. Since their client is usually the buyer, it is impractical to make intrusive and potentially damaging exploratory work. Therefore, a Surveyor and Engineer must rely on their experience and judgment to provide the best advice to the bank or buyer. Sometimes, the owner must facilitate the inspection by employing a builder to expose the structure as requested by the buyer’s surveyor or engineer. This process is complex and may result in the owner needing to make repairs and redecorate with no guarantee the purchaser will proceed. Thus, it is essential for owners to ensure all necessary consents are in place ahead of time and, if not, to anticipate these issues by consulting their own Structural Engineer before placing the property on the market.

We have surveyed many chimney flues in loft spaces that lack adequate support. While they may have lasted over time, this does not justify leaving them unaddressed.

An unsupported chimney stack or one inadequately supported by gallows brackets with uncertain top fixings poses a safety hazard. It is vital to remedy this situation before it leads to a collapse. Although there is no immediate risk, unless significant construction work is planned, which could cause severe vibrations, proactive measures should be taken.

The only reliable support solution that will typically receive approval from Structural Engineers, Surveyors, and lenders is to install an RSJ (Beam) or beams directly under the long leading edge of the stack. Normally, there are strong load-bearing walls nearby that can support a suitable arrangement of beams, which a Structural Engineer can design. Any beams installed perpendicular to the stack and resting on the Party Wall must comply with the Party Wall etc. Act of 1991.

Structural Engineers’ Reports on chimney breast removal

An experienced structural engineer will typically express concern if a chimney stack lacks proper support from conventional steel beams resting on solid load-bearing walls. Even if the stack appears safe today and the chimney breast has been removed for decades, it is wise to recommend adding appropriate support. This precaution is especially important before any major construction occurs nearby, either on the same property or in adjacent homes. This is because vibrations could loosen unsupported or inadequately supported brickwork.

While immediate action may not be necessary if no significant construction is planned, we advise buyers to consider the cost of adding such support. The estimated cost for this work, including accessibility, availability of supporting walls, builder size, and professional fees, typically ranges from £3,000 to £5,000.

Learning points

1. If you are selling a property where chimney breasts have been removed, obtain a Structural Engineer’s Report. Follow the report’s recommendations or share the findings with prospective buyers.
2. If commissioning builders to remove chimney breasts, ensure they apply for Building Regulations Approval and have the support works properly designed by a qualified engineer. It is no longer acceptable to “agree” on solutions informally with local councils.
3. If you are buying a property where chimney breasts have been removed, you will probably need a Structural Engineer’s Report unless the seller can provide proof of proper completion of the works.
4. If you are a surveyor working for a bank or private buyer and notice that chimney breasts have been removed, even if long ago, relying on the “test of time” is insufficient. Risk remains for potential hazards during building work in the attached properties. You should recommend obtaining a Structural Engineer’s Report or advise a financial contingency for addressing any issues.
5. If you are a builder you should avoid leaving areas unsupported or using gallows brackets. Consult with a Structural Engineer and adhere to their expert advice.

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Selecting builders and trades people poses numerous challenges for the public, a difficulty even industry professionals encounter. However, there are some helpful tips and pitfalls to watch out for. Having worked in the industry for 40 years, and conducted surveys and inspections where issues have arisen, I thought it might be useful to share my experiences to assist homeowners.

An overview

The public often has a negative perception of the building industry, anticipating unreliable suppliers, unexpected costs, and project delays. However, this perception does not reflect the experience of professionals within the construction sector. How can you as homeowners benefit from this insider knowledge?

The industry does have systemic issues within certain parts of the industry, being largely unregulated and populated by individuals with varying levels of experience and often lacking formal qualifications.

While the Internet offers easy access to suppliers, and numerous websites display impressive profiles for “approved” contractors, navigating these options can be a minefield despite improved quality assurance from these portals.

Often, as consumers, we contribute to problems in construction projects by prioritising the lowest price over detailed briefing and specifications, and wonder why it then goes wrong! We rarely buy the cheapest clothes or television or anything else in our lives that matters so why would we use this basis when working on our own homes which is probably our most expensive and prized asset of all?

The larger construction companies have stopped hiring apprentices or providing in-house training. Instead they prefer to outsource to specialised subcontractors, such as plumbers and electricians, hiring them as needed and releasing them once their tasks are completed. Many of these specialist trades operate as small businesses or independents, lacking the resources, financial stability, or job security to train employees on a permanent basis. Consequently, the industry is dominated by “one-man bands,” which limits opportunities for “on the job” learning and skill sharing, ultimately undermining quality and craftsmanship.

So how do you find the right person for the job?

Firstly, what to not to do when looking for a builder

Do not rely solely on the Internet, attractive advertisements, or professionally branded vehicles when selecting a builder as appearances can be misleading.

Even websites that verify a company’s proficiency often prioritise advertisers over those with established reputations who don’t require advertising as they have plenty of work.

While these portals might perform due diligence on the financial stability, insurance, and customer satisfaction of a company, they do not necessarily assess the technical competence to do the work. The technical ability to execute projects to a high standard, which professionals in the construction industry can confirm, is the most important criteria. Most builders recommended by architects and engineers do not need to advertise for work.

DON’T ask a friend

Asking for recommendations from friends or neighbours is a common approach which may work occasionally but usually doesn’t end well in our experience. While they often mean well, friends may recommend a contractor based on traits such as being “nice” or punctual, without the expertise to assess the technical quality of the work. For example, they might not recognise whether the right materials were used or if they meet the necessary strength requirements.

Other factors

Additionally, numerous financial and contractual issues deserve attention.

Questions such as whether your documentation forms a legally binding contract, if the pricing is fair, or whether payment should be made upfront are vital. It’s important to determine who is responsible for notifying local authorities under Building Regulations. Whether the Party Wall Act is applicable, and if landlord consent is necessary for flats or leaseholds. Also whether there are adequate plans and documentation to satisfy a landlord’s requirements.

Homeowners often face numerous complex issues they are unlikely to understand, and it may not be in a builder’s interest to clarify these matters fully. Some builders are unaware of when work needs to be reported to the Local Authority under Building Regulations or the Party Wall Act 1996, leading to complications that could be easily avoided. Even when projects seem to proceed smoothly, lacking formal approvals and paperwork can complicate future buying and selling of a property.

What should I do when looking for a builder or trades person?

The best course of action is to consult and appoint an industry expert, such as a professional, to manage the challenging tasks for you. This includes preparing specifications, scopes of work, and associated drawings, as well as obtaining quotes from their exclusive list of builders.

Chartered Architects, Chartered Building Surveyors, and Chartered Structural Engineers in London have dedicated their careers to making these precise selections for clients such as you.

You may think this sounds expensive, but be assured, faulty building work is far costlier than doing it right the first time. Building projects are inherently expensive. However, poor workmanship can lead to even greater expenses, beyond just monetary costs. The stress, delays, and lack of control contribute significantly to the overall burden, both financially and emotionally.

It is important to research and find the right professional based on their expertise, type, and size of work. As long as they are chartered and qualified, you should receive unbiased and professional advice.

If a project is too small, too specialised, or involves only one or two trades, local and smaller professional practices are only too happy to assist their local community by recommending suitable specialist contractors. This guidance is often offered as a professional courtesy and typically does not incur any charges.

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Following the tragic events at Grenfell Tower in North Kensington, West London, there have been sweeping changes regarding the responsibilities of all involved parties for the building works under UK Building Regulations. These changes extend beyond issues related to high-rise construction and fire safety.

For residential clients, it is recognised that lay persons may lack extensive knowledge of the building industry. Consequently, increased responsibilities have been placed on designers and builders/contractors. It is crucial to maintain a clear delineation of responsibilities for both design and construction. This ensures absolute clarity about who are the Principal Designer and the Principal Contractor.

Within the smaller sector of the building industry, there is concern about insufficient awareness among some builders and less informed designers, who may not be up to date with their training and professional development.

Why is the Building Safety Act 2022 so important?

Perhaps the biggest change is in the role of Local Authority Building Control Departments and how this affects smaller projects. Particularly the numerous small loft conversions and extensions that were previously completed using a “Building Notice” system. This informal approval process allowed builders to decide construction details on site without involving professionals such as architects, structural engineers, or building surveyors. This method is no longer possible. Building Control now focuses solely on reviewing design submissions from recognised professionals, which must adhere to by established and recognisable standards and codes of practice.

In situations requiring only a few steel beams and no architect, the structural engineer must take the additional responsibility of Principal Designer. Similarly, there must be a Principal Contractor responsible for the coordination of the building work, rather than relying on a disorganised selection of specialist contractors without a central figure responsible for the entire project.

Work is now overseen by a fully qualified and chartered professional

As a result of these changes, clients and builders must involve architects, structural engineers, and building surveyors more comprehensively in formal designs, specifications and calculations. Professionals undertaking this work should be able to demonstrate appropriate competence, ensuring that significant design decisions are made or overseen by a fully qualified and chartered professional.

This approach is expected to raise standards, increase work opportunities for qualified professionals and builders, and marginalise those lacking in these qualifications.

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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.

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