Built Environment Archives - Hawkins Forensic Investigation

Meet Yvonne Ainsworth: Geotechnical Engineer

Chloe Duggan — Tue, 23 Jun 2026 08:28:16 +0000

Yvonne joined Hawkins in December 2025 as a Principal Associate, bringing expertise in geotechnical engineering. She is a Chartered Civil Engineer and Fellow of the Institution of Civil Engineers (ICE), with extensive leadership experience across major infrastructure and energy projects. Her background combines technical expertise in geotechnical design and construction, with senior roles in operational management, risk, and HSEQ.

After graduating with a first-class degree in Civil and Structural Engineering from RWTH Aachen University, Yvonne began her career with WS Atkins before moving into specialist piling and geotechnical contracting. She delivered complex foundation and retaining wall projects, including Battersea Power Station and major Crossrail stations, and became a recognised authority in piling and diaphragm walling for high-risk schemes, both in the UK and internationally.

Yvonne later progressed into Director roles, overseeing geotechnical solutions for Energy from Waste and renewable energy projects. She then became Managing Director (Onshore) and subsequently Business Unit Director for Taylor Woodrow’s South Region, where she led a £40m portfolio and a multidisciplinary team.

We spent some time with Yvonne to learn more about her career journey and what brought her to Hawkins.

Tell us a bit about your background and your role at Hawkins

I have always been intrigued by how things work. During my Erasmus year in 1998/99, which I spent at Sheffield University, I learnt about geotechnical engineering, and it has fascinated me ever since. My degree was highly theoretical, so when I started my career, consultancy was the obvious choice. However, I soon realised that I didn’t fully understand how things were built. My employer gave me the opportunity to spend some time on site, and I truly fell in love with it. Having to make decisions quickly, often with limited information available was extremely exciting and rewarding. From that point on, I spent most of my career in construction.

I have now joined the geotechnical team at Hawkins, and am looking forward to broadening my experience into the wider civil and structural engineering world.

What motivated you to become a forensic investigator?

For as long as I can remember, I have approached problems with a forensic mindset. I have always been excited about uncovering what really happened when things go wrong, even though I have spent the majority of my career planning to prevent those situations in the first place. Before joining Hawkins, I was often sent to site to ‘figure out’ what was going wrong, whether this was operational, commercial or technical. This was arguably the most enjoyable part of my job, so the move to become a forensic investigator is probably not as big a change as it looks on paper.

What drew you to Geotechnical Engineering?

Geotechnics has always fascinated me because soil doesn’t behave like other engineering materials, it’s far less predictable. What you do to the ground in one area of site, is most likely producing a completely different response somewhere else. In addition to that, a lot of the work in geotechnics takes place below ground, such as piling, tunnelling or ground anchors, so you can’t directly observe it. As a geotechnical engineer, you rely on your experience, knowledge and a decent amount of intuition. I think that’s a great combination!

“For as long as I can remember, I have approached problems with a forensic mindset. I have always been excited about uncovering what really happened when things go wrong.”

What attributes do you consider important for a successful forensic investigation career?

Attention to detail, as well as logical and analytical thinking. Without those, you are unlikely to get to the bottom of what happened.

What’s the most interesting case that you have worked on?

I was once sent to Montreal, Canada, to help understand why the tendered drilling outputs were not being achieved as expected, and whether this was due to a change in ground conditions. Working in -35°C, surrounded by snow and ice, whilst observing the activities on site, was certainly an experience. What made this case particularly interesting was the combination geology, the effect of low temperatures, human behaviours and logistics. And I have never been to site with heated Portaloos since…

What do you love most about what you do?

I love being a geotechnical engineer. Solving problems or figuring out what went wrong is simply the icing on the cake. The most rewarding part is figuring out what happened and then someone else coming to the same conclusion. I love that I don’t consider my job as something I have to do, but rather something that I want to do. I’m excited that every day brings a new challenge or opportunity. It’s never boring or predictable!

What business advice would you give to your younger self?

Be patient. Good things sometimes take time.

Whilst I have become a lot more patient since having children (and probably with age) it’s still not my strong point. I often have to remind myself that some things simply need time. This is equally good advice when working with people: some people will be with you immediately, while others need time to take things in and digest the information. Be patient in your approach, don’t rush.

“I love being a geotechnical engineer. Solving problems or figuring out what went wrong is simply the icing on the cake.“

Do you have a favourite app, gadget or tool

I don’t have a favourite app, gadget or tool that I rely on for work, but I often go for a long walk or run to think things through in my head and evaluate different scenarios. Finding the root cause of an issue, often takes time and consideration, something that I find best done away from a desk.

What are the biggest challenges in the industry?

The biggest challenge in the industry is the skills shortage. Engineering, especially geotechnical engineering, is becoming less and less popular, and universities are struggling to fill available spaces. At the same time, the industry is losing a lot of experience through retirement or people leaving the profession at mid-career stage.

Another challenge is the mindset around learning. Too often I hear people say, ‘Oh, I did that 3 years ago, I can’t remember now.’ Learning shouldn’t be just about passing an exam, it needs to be continuous and long-term. Understanding the fundamental principles of engineering is vital as a forensic investigator.

Where do you see the industry evolving in the future?

I can see that technology and digitalisation will play an ever-increasing part in the way we build, and therefore in the way things will go wrong. But new technologies will also create opportunities for forensic investigation, whether through the speed with which we access information, improved analysis tools, or new ways of interacting with others and examining scenes. We need to embrace the technological advances and use them to our benefit.

What differentiates Hawkins from other forensic investigation/consultancy firms?

From my experience so far, the biggest difference is the level of investment in staff development. Training is given the top priority, and all aspects of the business contribute to it. I also have to say that everything is much more organised here than any other business I have worked for in the past.

“I can see that technology and digitalisation will play an ever-increasing part in the way we build, and therefore in the way things will go wrong...We need to embrace the technological advances and use them to our benefit.“

Tell us something about yourself outside of work

Apart from the fact that I am German, which, with a name of Yvonne Ainsworth, is not that obvious, I like to stay active. I enjoy going to the gym, playing pickle ball or taking the dog for a walk. I also used to be qualified football referee and once officiated an U18 Arsenal match, and I now coach my daughter in her refereeing career.

What’s something you have done, but will never do again?

Sky diving. I’ve always said I try everything once, but I hated every second of it and screamed the entire way down.

What is your guilty pleasure?

Having a mid-afternoon snooze at the weekend.

Do you have a hidden talent?

People often say I have a crystal ball to predict the future (and no, I can’t tell you the lottery numbers). I call it intuition and gut feel.

What is the top destination on your must-visit list and why?

I have been fortunate enough to visit my must-see destinations. In my thirties, and before having children, I took a year out to travel the world. I visited India, Nepal, Southeast Asia, and Australia. I’ve always loved travelling and experiencing other cultures. I have also been to New Zealand, most of Europe, America and Canada. Africa and South America are still on my bucket list.

What is one song you have completely memorised?

Hakuna Matata from The Lion King. Don’t ask me why.

If you would like Yvonne or another Hawkins expert from another discipline to investigate a case or present to your organisation, please contact us.

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Acoustic Design In School Buildings

Chloe Duggan — Mon, 22 Jun 2026 08:02:35 +0000

Acoustics is an important factor to consider when designing school buildings, because it affects the quality of communication and learning in classrooms and other spaces. Poor acoustics can make it difficult for students and teachers to hear and understand each other, leading to frustration, fatigue, stress, and reduced academic performance. Good acoustics can enhance speech clarity and create a comfortable and productive learning environment.

The UK Department of Education published the Acoustic Design of Schools: Performance Standards, Building Bulletin 93, in 2014. This set out the requirements for indoor ambient noise levels, reverberation times, and sound insulation for new and refurbished school buildings. These requirements are also linked to the Building Regulations, the School Premises Regulations, and the Independent School Standards.

One of the main factors affecting classroom acoustics is the indoor ambient noise level, which is the sound level in the room when no one is speaking. This noise can originate from external sources, such as traffic, construction, or playgrounds, as well as internal sources, such as ventilation, heating and cooling systems, or other equipment. High indoor ambient noise levels can mask or interfere with the speech signal, making it harder for listeners to hear and comprehend what is being said. Low indoor ambient noise levels can allow quiet, yet audible, disturbances to be far more distracting than they usually would be. This can affect the ability of students to follow instructions, participate in discussions, and concentrate on their work.

Another factor that affects the acoustics of a classroom is the reverberation time of the space. In layman’s terms, it is the ‘echo’ in a room, but technically, it is defined as the time it takes for an impulsive sound (such as a hand clap or a balloon burst) to decay by 60 decibels. Reverberation is caused by sound reflecting off the room’s surfaces, such as walls, ceilings, floors, or furniture. Reverberation targets vary depending on the type of room and activity planned for the room. For instance, a piano rehearsal music room will not have the same requirements as a classroom, and a dining hall will not have the same requirements as an assembly hall. This is because reverberation can be detrimental to speech, especially in large or crowded rooms, but is not necessarily detrimental to music in the same way. Long reverberation times can make speech sound muffled, distorted, or ‘echoey’, reducing its intelligibility and increasing the listening effort. It can also affect the vocal health of teachers, who may have to strain their voices to speak louder or more clearly. This can affect students’ learning outcomes, especially those with hearing impairments, language difficulties, or special educational needs (SEND).

Acoustics is especially important for the design of SEND schools because many students have hearing or communication challenges, or other conditions that affect their listening and learning abilities. According to the 2010 Equality Act, all schools have a responsibility to improve their accessibility plans for pupils and staff, and this includes providing optimal acoustic conditions.

Some of the strategies that acoustic engineers can use to improve the acoustics of schools include:

Choosing a suitable location and orientation for the school building, away from noisy sources or facing away from them to minimise the impact of external noise on the school environment
DevelopmentUsing sound-absorbing materials and finishes, such as acoustic tiles, panels, or carpets, to reduce reverberation s that could be affected by sources of flooding other than rivers and the sea (for example surface water, sewers, groundwater and infrastructure failure)
Installing sound-insulating materials and structures, such as double-glazed windows, doors, or walls, to block or reduce external or internal noise
Making use of acoustic barriers or screens, such as fences, hedges, or walls, to deflect or attenuate noise from outside or inside the school
Using acoustic baffles or diffusers, such as suspended ceilings, shelves, or furniture, to scatter or redirect sound waves and improve sound distribution
Ensuring mechanical ventilation, heating, and cooling systems are quiet, well-maintained, and are acoustically treated
Using sound amplification or enhancement systems, such as microphones, speakers, or hearing loops, to improve the speech-to-noise ratio and the audibility of speech. These systems can amplify the speaker’s voice and deliver it directly to the listener, or to a hearing aid or cochlear implant.

Given the propensity to affect the quality of communication and learning in classrooms and other spaces, acoustic consideration is an essential aspect of the design of schools.

By applying the principles and practices of acoustics, acoustic engineers play an instrumental role in creating school buildings that provide optimal teaching and learning conditions for teachers and students.

If you have an acoustical related issue and need the services of our Acoustics Consultancy team, please contact us.

References

Equality Act 2010 – https://www.legislation.gov.uk/ukpga/2010/15/part/6

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Hawkins Experts Present at Crawfords MCL Surveyors Technical Forum

Chloe Duggan — Thu, 11 Jun 2026 15:58:46 +0000

Hawkins Built Environment experts recently delivered a presentation at the Crawfords MCL Surveyors Technical Forum, providing attendees with a detailed look at the forensic investigation of property damage claims linked to extreme weather and structural loading.

The session was led by Jamie Paterson, Jack Allison and Simon Bateman, who shared their combined expertise through a series of case studies examining storm-related damage, snow loading, and subsidence.

The presentation explored how forensic engineering principles are applied to determine the root cause of structural failures, with particular emphasis on distinguishing between sudden, insurable events and gradual deterioration. Using real-world examples, they demonstrated how factors such as snow loads, wind forces, water ingress, and pre-existing defects can interact to compromise buildings in complex insurance claims.

Jamie explored cases involving snow loading, highlighting the challenges in assessing claims where data may be limited and conditions vary significantly. He emphasised the importance of comparing observed conditions against design standards and assessing whether structural capacity may have been reduced over time due to maintenance issues or degradation.

Simon presented case studies on storm damage and rainwater ingress, illustrating how detailed investigations, often incorporating historical records, site inspections and aerial imagery, can reveal whether weather events alone were responsible or whether underlying weaknesses in the structure played a key role.

Jack concluded with a subsidence-focused case study, demonstrating how forensic analysis can establish the timing and progression of damage, which is critical when determining policy response. His presentation highlighted the importance of historical evidence and site conditions in distinguishing between ongoing ground movement and newly occurring damage.

A consistent theme throughout the session was that successful claims investigation relies on a thorough understanding of both external forces and the internal structural condition, alongside the ability to interpret multiple sources of evidence. The forum provided an opportunity for surveyors and insurance professionals to gain practical insight into how forensic investigations support decision-making in complex claims.

If you would like one of our experts to investigate a case or present to your organisation, please contact us.

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Secant Pile Walls & Basement Excavations: What Could Possibly Go Wrong?

Chloe Duggan — Mon, 08 Jun 2026 08:05:43 +0000

Basements are now routine in urban developments – from plant rooms and car parks to premium residential space. Yet “routine” should not be confused with “simple”. Underground works introduce a unique set of construction risks, which, if not properly managed, can lead to significant issues, increased costs and programme delays. When properly executed, these works enable the construction of challenging basements, even on constrained sites and in areas with high groundwater tables.

Many properties now require basement construction. In most cases, this is achieved using embedded retaining walls, especially in places with limited space with each option. Where groundwater is present, an embedded retaining wall type must be chosen that can retain the groundwater. Sheet pile, secant pile or diaphragm walls are feasible options. CIRIA C760 ‘Guidance on embedded retaining wall design’ provides selection guidance across wall types.

Secant pile walls, in particular, are widely used because they provide support in both temporary and permanent conditions and can be adapted to suit challenging sites. They retain ground and groundwater, minimise ground movement and can carry substantial vertical loads.

Basements may be routine, but they are not simple. Poor planning and/or execution can lead to significant technical issues, cost overruns, and programme delays. Due to their frequent use, this article focuses on secant pile walls – their role, what can be expected of them and the common issues associated with their design and construction.

What is a Secant Pile Wall?

A secant pile wall is a continuous wall formed by interlocking bored piles, as shown in Figure 1.

Primary piles, often referred to as female piles, are installed first, and secondary piles, also known as male piles, are drilled so that each one cuts into the adjacent primaries, creating an interlocking line of concrete. Primary piles are typically unreinforced (see Figure 2).

This system of interlocking primary and secondary piles creates a hard/soft or hard/firm secant wall. The difference between the two wall types is the concrete strength in the primary piles. If the secant wall is used as temporary works only, there is no need for durability or strength requirements for the unreinforced pile, and non-structural concrete may be used. Due to advances in rig power and the cost of using secant walls as temporary works only, hard/soft secant walls have become less common compared with hard/firm secant walls where the primary pile often consists of a low-grade structural concrete, such as a C8/10.

However, in very deep excavations and in response to additional structural requirements, it may be necessary to also reinforce the female piles (see Figure 3). This combination then becomes a hard/hard secant wall which uses high grade structural concrete in both primary and secondary piles.

Secant walls can be constructed using various techniques:

The choice of technique depends on the project requirements, especially permissible tolerances, retained height, depth of interlock required and prevailing ground conditions, see Figure 4. Interlock is the length of wall over which the secondary piles cut into the primary piles. This distance is of particular importance for groundwater exclusion.

Achievable tolerances and typical depth of interlock are defined in the ICE Specification for Embedded Retaining Walls (ICE SPERW) in Table B1.4 and partially reproduced below in Table 1. Whilst the verticality of wall and depth of achievable interlock increase from CFA towards RBP, so does the cost, complexity and the timeframe to install the secant wall.

Advantages of Secant Pile Walls

There are numerous reasons why secant pile walls are often the preferred solution for basement construction:

1. Space Efficiency in Constrained Sites

Urban basements are frequently built tight against property boundaries or adjacent structures. This makes secant walls ideal for city-centre projects where every metre counts.

2. Groundwater Management

Secant walls provide an effective horizontal water barrier when installed correctly. This is particularly valuable where high water tables or sensitive neighbouring assets are present. However, they do not necessarily mitigate vertical groundwater flow into the excavation and should be used in conjunction with a groundwater management strategy (CIRIA C750 ‘Groundwater control: design and practice’).

3. Structural Versatility

Secant walls can serve both as temporary excavation support and as part of the permanent basement structure, reducing duplication of work. They can be designed to carry substantial loads, making them suitable for deep basements and complex load cases.

4. Adaptability

Secant pile walls can be constructed using a variety of piling techniques to address a range of retained heights, tolerance requirements and ground conditions. Secant walls can also adapt to accommodate many footprint shapes. This flexibility makes secant walls a practical choice for many UK ground profiles.

Where Things go Wrong

On paper, secant pile walls look like the perfect solution: strong, versatile, and great for tight sites. But in the real world, things do not always go to plan. Here are the most common issues we see and why they matter.

Misalignement

Secant walls depend on the interlock between primary and secondary piles. However, piles (typically secondary piles) can become misaligned for a variety of reasons, see Figure 5.

Some common root causes for misalignment are given below:

> Primary concrete too hard, causing the secondary pile to deviate into ‘softer’ soil. This is often caused by inadequate or untested concrete mix design and is most commonly seen in CFA walls.

> Incorrect sequencing. Sequencing is of particular importance in CFA secant walls. If the sequence is not planned properly, or disrupted due to site changes or plant breakdowns, the concrete in the primary piles may become too hard, resulting in the defect described above.

> Incorrect technique chosen for interlock requirements. Due to the significant increase in costs from CFA to CCFA and RBP, the interlock limits of CFA are frequently pushed. Joints, especially in standard CFA augers, create a degree of flexibility and make it easier for piles to deviate from the vertical. To minimise this risk, having fewer joints in the auger is better.

> Obstructions in the ground, either natural (such as boulders) or man-made (in the form of old foundations or walls etc.), can cause piles to deviate from their intended position and verticality. RBP techniques are best placed to deal with obstructions in the secant wall alignment and should be chosen if obstructions cannot be removed prior to secant wall construction.

Misaligned piles can affect projects in multiple ways. If the interlock between primary and secondary piles is broken, unwanted soil and water can ingress into the excavation, which will require immediate remedial works (typically through resin injection).

Having sufficient interlock is not only important where it can be seen, i.e. above excavation level, but also below this level to guarantee sufficient water cut-off to make the excavation safe and free of running water. Groundwater entering the excavation from the bottom can destabilise the soil and, in extreme cases, cause uplift failures which should be considered in the geotechnical design of the basement (BS EN 1997-3:2025 – Eurocode 7 – Geotechnical design. Geotechnical structures). To avoid these, the design of the basement should be accompanied by a groundwater management strategy (CIRIA C750 ‘Groundwater control: design and practice’).

In severe cases, a misaligned pile (shown in Figure 5) can impact the spatial requirements of the basement, e.g. the position of liner walls. In these cases, either the out-of-position pile or the secondary element will require structural modification, potentially impacting layouts, available space or structural capacity of the secant wall itself.

Water Ingress

For the avoidance of doubt, secant walls are rarely found to be perfectly watertight. Due to the number of joints between primary and secondary piles, secant walls are vulnerable to water ingress. Damp patches and beads of water (individual droplets of water) are to be expected and do not constitute a defect. The size of damp patches, however, should be less than 4m² per patch, or less than 10% of the visible face of the wall (refer to ICE SPERW 3^rd Edition, Clause B1.9.1 for further details). Weeping water, i.e. where the water runs down the face of the wall, is not acceptable.

Water ingress may occur even if there is no visible sign of misaligned piles. An allowance should be made in the construction programme to permit the piling contractor to deal with leaks through resin injection or other sealing methods.

It is also important to understand that secant walls are classified as Type B protection against water ingress (see BS8102:2022, Table 1) and alone cannot provide a performance level better than Grade 1b (no seepage, damp areas from internal and external sources are tolerable) in accordance with BS8102:2022, Table 2.

Protrusions

Protrusions refer to irregularities on the exposed face of a secant wall after excavation, see Figure 8. Instead of a vertical surface, the wall may have protrusions extending beyond the face of the wall into the excavation. Whilst this is not a structural defect, it can have consequences for follow-on trades and potentially the construction programme.

Protrusions frequently occur in

> Loose natural granular soils or soft clay deposits

> Poorly compacted or poorly graded backfill after obstruction removal (often associated with the removal of an old basement).

> Certain ground conditions where over flighting is a risk associated with CFA techniques (refer to FPS Guidance paper ‘CFA Piling: Preventing ground & rig instability through over-flighting’).

Protrusions in soft/loose/insufficiently compacted ground cannot easily be controlled by the piling contractor. The piling contractor is only responsible for the removal of protrusions in excess of 100mm thickness (ICE SPERW 3^rd Edition, Clause B11.4.2). It is therefore important to allow sufficient time in the construction programme to deal with protrusions, although it is structurally permissible to leave protrusions in place unless they interfere with waterproofing or finishing works.

Concrete Defects

Concrete quality is critical for durability and long-term performance of secant pile walls. Defects can occur during placement and often remain unnoticed until later stages. Using a trialled and tested concrete mix design from established concrete suppliers and undertaking concrete performance testing, are effective ways to minimise the risks of defects. How the concrete is handled on site, for example, avoiding changes to concrete properties through the addition of water, and ensuring the timely and appropriate placing of concrete in accordance with the relevant standards, such as BS EN 1536, ICE SPERW, EFFC Tremie Guide is also of vital importance. Inadequate base cleaning or support fluid exchange, poor tremie practice (RBP only) or concrete supply interruptions can also affect the final product.

Some common concrete defects in secant walls include:

> Shadowing/mattressing, refers to situations where concrete does not flow adequately around the reinforcement bars and leaves ‘shadows’. This defect only occurs in rotary piles.

> Inclusions in piles, which are a common problem and are often the result of inadequate concrete workability. They consist of entrapped materials that differ from the specified concrete and can originate from the surrounding ground (soil or groundwater), poorly cemented material from the original segregated concrete, and may also contain drilling fluids (if used during construction). Inclusions occur more frequently in rotary bored piles as the concrete is placed after the installation of the reinforcement cage and must flow around the bars, but can also occur in CFA or CCFA piles when the concrete has lost its workability.

As a result of inclusions, concrete cover becomes inadequate requiring remedial work. If the inclusions are extensive, they may also provide additional pathways for water ingress (though the reduction of interlock) and may require the down-rating of pile/wall capacity.

What to Expect

Many disagreements occur when expectations between parties are not aligned. The points below summarise what can reasonably be expected:

Secant pile walls are not fully watertight

Secant pile walls manage groundwater inflow, but they do not provide completely dry basements. Damp patches or minor seepage are common and should be anticipated. Flowing water or concentrated leaks, however, are unacceptable and usually indicate defects requiring remedial works. Waterproofing should always follow BS 8102:2022 guidance, with allowances for remedial sealing such as resin injection.

Damp spots do not mean defects

Clients often expect a completely dry basement. In reality, even with a well-built secant wall, some moisture may appear. This is normal and should be addressed through the waterproofing strategy, not treated as a defect.

Overbreak is common

Expect some irregularity on the exposed wall face after excavation. Overbreak often occurs in loose granular deposits, soft clays, or poorly compacted backfill from obstruction removal. Whilst it does not present a structural problem, it complicates waterproofing and finishing works. Extra trimming or patching may be needed, which can affect programme and cost.

Straightness varies by technique

Walls formed using rotary bored piling (RBP) tend to achieve better verticality, greater interlock and straighter faces than those installed with CFA methods. However, while these advanced systems deliver superior alignment, they come at a higher cost.

Consequences for Projects & Claims

When secant pile walls do not perform as expected, the impact is rarely minor. Even small defects can significantly affect the programme and budget. The following outcomes are typical:

Remedial Waterproofing

If water ingress occurs, the leaks are usually treated by polyurethane or acrylate gel injection. This treatment generally stops the leak but can be very disruptive. Injection requires specialist contractors, access to the affected areas, and often multiple visits. Blocking one leak often causes others to appear, meaning costs can increase quickly, and programmes become delayed.

Additional Surface Preparation

Whilst overbreak may be more of a cosmetic problem, it can mean that the wall face is not ready for waterproofing straight away. Trimming, patching, or applying thicker coatings adds time and labour. These tasks are rarely in the original programme, so delays are common.

Structural Downgrades

In rare cases, if tolerances or concrete quality fall short, the wall’s structural capacity may need to be reassessed. This can lead to redesigns, additional props, or strengthening measures, all of which add cost and complexity.

Programme Delays and Cost Overruns

Every remedial step, whether sealing leaks or smoothing surfaces, pushes the schedule out. Waterproofing trades cannot start until the wall is prepared, and follow-on activities like slab casting or fit-out are held up. Claims for delay and disruption are common in these scenarios.

Bottom line: Defects, even cosmetic ones, can have significant commercial consequences. Early planning, engagement with relevant specialists, realistic tolerances, robust quality control, and allowances in programmes are the best approach to avoid subsequent issues.

From our experience, it is essential to follow these steps to minimise issues on site or disputes:

> Define the waterproofing performance grade early (BS 8102:2022) and appoint the waterproofing specialist at the concept stage.

> Select the right wall type for depth, deflection limits and groundwater context (CIRIA C760).

> Make allowances for realistic tolerances (ICE SPERW).

>Plan groundwater management: combine secant cut‑off with dewatering where required; design for uplift; protect adjacent assets (CIRIA C750).

Conclusion: Why Early Attention Matters

Secant walls make complex basements possible, but they are not an “install and forget” solution. Misalignment, protrusions, water ingress, and concrete defects are all common issues that can lead to extra work, cost, and programme delays. Most “problem basements” are not the result of a single catastrophic error – they often stem from a series of small, foreseeable mismatches between design assumptions, construction tolerances, and waterproofing expectations. Addressing those early is far cheaper than dealing with issues later. Standards and guidance exist; the key is to use them proactively.

If you are facing secant wall performance questions, planning a deep basement, or navigating a claim, Hawkins can help – from early risk reviews and design due‑diligence to independent failure analysis and expert evidence. We translate complex geotechnical issues into clear advice and defensible conclusions for clients, contractors and insurers.

About the Author

Yvonne Ainsworth is a Chartered Civil Engineer and Principal Associate at Hawkins, with over 25 years’ experience in geotechnical and structural engineering. Her career includes senior roles delivering complex foundation and retaining wall projects, including secant and diaphragm wall construction on major UK infrastructure schemes. Yvonne is widely recognised for her expertise in piling, ground engineering and resolving high-risk technical challenges, with experience directly relevant to the behaviours, risks and performance of secant pile walls discussed in this article. She brings specialist insight into design, construction methodologies, and failure investigation in complex ground conditions.

References

BS 8102:2022 – Protection of below ground structures against water ingress — Code of practice

BS EN 1536:2010 (+A1:2015)- Execution of special geotechnical works – bored piles

BS EN 1997-3:2025 – Eurocode 7 – Geotechnical design. Geotechnical structures

CIRIA C750 – Groundwater control: design and practice, second edition, 2016

CIRIA C760 – Guidance on embedded retaining wall design, 2017

EFFC Guide to Tremie Concrete for Deep Foundations, 3^rd Edition,2024

FPS Guidance Paper ‘CFA Piling: Preventing ground & rig instability through over-flighting’, 2014

ICE Specification for Piling and Embedded Retaining Walls, 3^rd Edition, 2016

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Hawkins Hosts Inaugural ‘Burning Questions’ CPD Reception in Dublin

Chloe Duggan — Thu, 04 Jun 2026 10:28:14 +0000

Hawkins recently hosted our first Burning Questions event in Dublin, welcoming clients, colleagues, and industry professionals to The Merrion Hotel for an engaging session focused on forensic fire investigation.

The afternoon began with an informal welcome over tea and coffee, before guests attended a CPD presentation accredited by The Insurance Institute of Ireland. Delivered by Hawkins experts and guest speakers, the session provided both technical expertise and practical insight.

John Holland, Regional Director for the Island of Ireland, opened the event with an update on Hawkins’ continued growth and development. He highlighted our recent international expansion into Italy, Abu Dhabi, South Africa, and Australia, as well as the acquisition of A. Lamb Associates (ALA) and its subsidiary, Morham + Brotchie Partnership (M+B). This development strengthens Hawkins’ ability to provide integrated technical, quantum, and delay expertise on a single case, enhancing the service provided to clients.

The presentation centred on a detailed, multi-disciplinary case study, taking attendees through each stage of a complex fire investigation from identifying the origin through to recovery considerations. The scenario explored a fire caused by a defective e-scooter, which spread rapidly through a terrace of converted residential properties, raising important questions around causation, fire spread, liability, and compliance with construction standards.

Ian Stafford, Major and Complex Loss Adjuster at Davies Group, outlined the practical challenges of handling significant losses and emphasised the value of early investigative input. Hawkins fire investigator Jason Buchwitz explained how the origin of the fire was identified and alternative causes eliminated, while structural engineer Killian Walsh explored how shortcomings in fire-stopping contributed to the spread of the fire.

Legal considerations were addressed by Martin Browne of HF (formerly Horwich Farrelly), who discussed potential recovery routes and liability issues. The session concluded with insights from Hawkins’ forensic architect Paul McCaughran, who highlighted design and construction shortcomings that failed to meet building regulation requirements.

The event demonstrated how a coordinated, multidisciplinary approach can effectively resolve complex claims, offering attendees a clear understanding of how expertise across disciplines contributes to determining cause, responsibility, and outcome.

Following the presentation, guests attended a drinks reception with canapés, providing an opportunity to continue discussions in a more informal setting. Attendees also had the chance to explore casework exhibits, including virtual reality photogrammetric models, offering a closer look at the investigative techniques discussed during the session.

Thank you to everyone who joined us, we look forward to welcoming you to future Hawkins Events.

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Christopher Bowler

Chloe Duggan — Tue, 19 May 2026 16:10:19 +0000

Christopher is a Chartered Architect, registered Building Regulations Principal Designer, and experienced Contract Administrator, with a strong track record across design, compliance, and delivery roles. His recent work at PRP Architecture LLP has focused on residential fire safety remediation, where he has operated at the intersection of technical and managerial responsibilities. He is a member of PRP’s Building Regulations Principal Designer steering group and is listed on the RIBA Higher-Risk Building Principal Designer Register.

In his recent role, Christopher led advisory services for a housing association client managing a £175 million portfolio of Building Safety Fund grant applications. His involvement spanned the full remediation lifecycle, including portfolio risk assessment and prioritisation, technical specification, procurement, and contract administration during delivery. His ability to integrate regulatory compliance with practical project execution has been central to the successful progression of these complex programmes.

Christopher holds an MPhil in Environmental Design in Architecture from the University of Cambridge, where he was awarded an Exhibition. He qualified as an architect in August 2013 and has since gained extensive experience delivering projects across the UK and internationally, with values up to £600 million. His portfolio includes a diverse range of construction types such as new-build concrete and steel structures, traditional brickwork, timber frame, and the refurbishment of heritage stone buildings, delivered under a variety of procurement routes and contract forms. His multidisciplinary background enables him to effectively bridge design intent, regulatory obligations, project management, and contractual frameworks, ensuring robust and compliant project outcomes.

In addition to his architectural practice, Christopher brings five years of experience within a built environment forensics team, further strengthening his analytical approach to risk, defect investigation, and building performance.

Christopher joined Hawkins as an Associate in February 2026 and is based in our London office.

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Ewan Slight Featured in The Voice of Foil

Chloe Duggan — Wed, 15 Apr 2026 13:45:12 +0000

Hawkins is delighted to announce that Ewan Slight, Principal Associate and Chartered Quantity Surveyor, has been featured in the latest edition of The Voice of FOIL (Forum of Insurance Lawyers) Magazine.

In his article System Dynamics: An Alternative Approach to Construction Claims, Ewan explores one of the industry’s most persistent challenges: accurately evidencing productivity loss caused by disruption. Despite widespread use, traditional approaches, such as ‘global claims’ and ‘measured mile’ analysis, often struggle to demonstrate clear cause-and-effect relationships. Ewan explains why these methods can fall short, highlighting issues such as weak causal linkage, difficulties identifying unimpacted baselines, and problems with concurrency.

System Dynamics (SD) is a modern and technically robust approach for assessing construction disruption claims. By modelling construction projects as interconnected systems, SD captures cumulative impacts, feedback loops and non-linear interactions that traditional forensic methods may overlook. Through tools such as Causal Loop Diagrams and Stock & Flow modelling, SD provides transparent, data-driven simulations that demonstrate how disruption develops over time.

Ewan emphasises that System Dynamics offers significant advantages for dispute resolution, including improved quantum validation, greater evidential robustness for litigation or arbitration, and deeper portfolio-level risk insights. Its methodology is also aligned with the Society of Construction Law Delay Protocol.

Ewan is a Chartered Quantity Surveyor with more than 30 years’ experience in the construction and infrastructure sectors. He specialises in quantum analysis, delay, and disruption within major and complex disputes, and has held roles ranging from equity director to independent expert. Ewan is a RICS Registered Expert Witness, with experience delivering expert opinion and responding to adversarial questioning during pre‑hearing proceedings. By integrating quantum expertise, forensic delay techniques, and dynamic disruption modelling, Ewan provides robust, defensible evidence for litigation and arbitration. His work supports clients and legal teams by bringing analytical clarity, evidential rigour, and sound professional judgement to complex disputes.

Follow the link if you would like to watch Ewan’s Webinar: System Dynamics, A Smarter Way to Prove Disruption in Construction Projects.

Or read Ewan’s article on page’s 27-28 of February’s edition of The Voice.

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Hawkins Welcomes Highways Engineer Connor Parkes

Chloe Duggan — Tue, 14 Apr 2026 16:17:46 +0000

Hawkins is pleased to welcome Connor Parkes, who joins us after more than 12 years in the highways and civil engineering industry. Connor brings extensive experience in highways asset management, stakeholder coordination, and ensuring the long-term resilience of local authority infrastructure.

Alongside building his professional experience, Connor completed his BEng (Hons) in Civil and Transportation Engineering, achieving IEng status and membership of both the Institution of Civil Engineers (MICE) and the Chartered Institution of Highways and Transportation (MCIHT). He is also a Fellow of the Institute of Highway Engineers (FIHE), and a member of The Association for Road Risk Management (MARRM).

Connor previously worked as a Highways Asset Management Engineer, contributing to a multi‑year contract valued at over £100 million. In this role, he played a key part in ensuring public safety, maintaining highway quality, and achieving maximum efficiency from public funding allocated to essential road infrastructure.

He has also supported local authorities during the delivery of major highway works connected to a multi-billion-pound national rail scheme. His role focused on ensuring that new highway assets constructed across Staffordshire met the required standards for future adoption and long-term maintenance by the authority.

Connor joined Hawkins in December 2025, where he will be working predominantly on highways schemes. We are delighted to have him on board and look forward to the valuable expertise he brings.

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Do I Have a Cladding Dispute?

Chloe Duggan — Mon, 13 Apr 2026 09:45:05 +0000

Over recent years, the safety of a building’s cladding has become a major concern in the UK and the UAE. This is primarily due to the use of combustible cladding materials and ill-fitted or absent fire stopping.

The typical cost of recladding an 18-metre tall building is in the region of £4-5m in both the UK and the UAE. This has led building owners and occupants to consider whether these costs can be recovered from other parties.

Before being able to answer the question, a prospective claimant must first ask ‘do I have unsafe cladding?’. Safety concerns regarding cladding includes structural and fire issues, but this article will focus on non-load bearing facades and therefore fire safety concerns only.

Many of the headlines covering combustible cladding materials initially focused on aluminium composite panels (ACP). However, a building clad in ACP is not the only type of material which could present a risk. There are other cladding types, such as high pressure laminates and external insulated render systems known as EIFS, ETICS or EWI, which may appear to be acceptable but could give rise to a claim.

How do I Know if a Building’s Cladding is Defective?

Defective cladding could be due to the design, construction (installation and workmanship related defects) or both. Design and construction are governed by local building codes, and it is necessary to review a building based upon the codes relevant at the time of design and construction.

In England and Wales, the current relevant codes include the Building Regulations 2010. In the UAE, the current relevant codes include the Fire and Life Safety Code of Practice 2017.

Was the Design Defective?

In England and Wales, there is more than one route to demonstrating compliance with the fire safety requirements of the Building Regulations that the designer/s could have followed:

Linear route: Following the guidance in the Approved Documents, although this does not guarantee compliance with the Regulations.
Performance route: Demonstrating that the performance criteria for external walls in BR 135 have been met by using fire test data from a large-scale BS 8414 test to determine how the proposed façade build-up performs in a fire.
Fire safety engineering route: This would generally follow the recommendations in BS 7974 ‘Application of fire safety engineering principles to the design of buildings – Code of practice’ and take the form of a desktop study that states whether the performance criteria in BR 135 would be met, and as set out later in this article.

Whilst the UAE did not develop its own Fire Life Safety Code until 2011, with the National Fire Protection Association (NFPA) standards being adopted previously, it has been quicker than many other countries to update and introduce more stringent requirements following significant fires.

The review of a design’s compliance with the Code is undertaken by the Civil Defence Authority, although compliance with the code is still the responsibility of the consultant. Any façade system must have been tested and approved by the Civil Defence Authority and the relevant and current approval certificate must be submitted as part of the application for Civil Defence Approval. This, in theory, means that, a design post2011 should not be defective.

However, a building gaining building control or code approval does not necessarily mean that the cladding as designed and installed meets the functional requirements and is not defective.

The most common design defects we have come across at Hawkins include the lack of fire barriers and/or cavity closers. Both of these defects can lead to extensive areas of the external envelope of a building where the spread of fire could be hidden from view. The restricted nature of these cavities can lead to flames that extend up to 10 times the height they would otherwise reach if they were not within a cavity.

The Consultant Told me the System had Been Tested

In the UAE cladding systems must be tested to NFPA 285, which replicates a fire breaking out in the building, spreading through the glazing and igniting the external façade. The test determines the fire performance of an exterior, non-loading bearing wall assembly.

BS 8414, first published in 2002 and some 30 years after the origins of NFPA 285, also provides a test method for determining the fire performance of non-load bearing external cladding systems. The standard is split into two parts; part one tests systems applied to the masonry face of a building, whilst part two tests systems applied to a structural steel frame.

There are a number of issues with statements that a system has been tested to a standard:

Firstly, what was the result? Results for BS 8414 tests are generally not made publicly available, and the BS 8414 test results are not given as a pass or fail (this must be determined by using BR 135). In the UAE, NFPA 285 are available as part of a supplier’s marketing material and without it their products are unlikely to be specified.

Secondly, is the system tested going to be applied in the same way as the test? A masonry applied system will behave differently than a steel frame applied system.

Thirdly, does the system tested match exactly what was proposed for your cladding system? For example: where fire barriers are installed around openings in the test is the insulation the same; and, if it is, is it the same thickness? In one of our cases, it was stated that the EIFS system was tested to BS 8414. The test was relevant for insulation thickness up to 200mm yet the designed system was 320mm in places

The Fire Engineer Said the Design was OK

By following BS 7974, fire engineers can use an analytical process based upon a qualitative design review, in which the possible ways a fire hazard may arise are considered and a range of strategies adopted to ensure that the risk is kept to an acceptable level. This process has a number of stages, including:

A review of the architectural design of the building
Establishment of the fire safety objectives
Identification of fire hazards and the possible consequences
Establishment of trial fire safety designs
Identification of acceptance criteria and methods of analysis
Identification of fire scenarios for analysis
Assessment against criteria.

As you may be able to tell, this is not a quick exercise, and a fire engineer should provide a substantiative reason as to why the guidance in Approved Document B has not been followed, together with supporting evidence to show how the Buildings Regulations are being complied with through another route.

Was the Installation Defective?

What the consultant draws is not always what gets built. Defects we have encountered include lack of fire barriers, intumescent strips to fire barriers impeded so they cannot act as designed during a fire, and incorrectly installed EIFS resulting in cavities between the back of the insulation and the supporting structure.

It is likely that only an intrusive survey will be able to determine if there are defects in the installation. However, an intrusive survey needs to be carried out correctly and those carrying out the survey must understand what they are looking at. In one instance, I have seen a surveyor incorrectly label solid aluminium cladding as ACP, which will have had an effect on the building owner’s insurance premium. In another instance, a surveyor had considered that a lack of cavity barriers in an external wall, indicated that there had been a breach of the Building Regulations, despite the layout of the building meaning there was no other compartment to which a fire could spread.

The above points provide some insight as to whether building owners have a potential route to bring a claim for the costs of remedial works either against consultants, contractors, or possibly both, before a building fire highlights any defects and when it may be too late to ascertain defects in construction.

About the Author

Austen Smith is a Forensic Architect in Hawkins’ Dubai office who specialises in construction defects and defects in architectural design. He has twenty years’ experience in construction projects spanning Europe, the Middle East, the CIS, East Asia and Australia.

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Congratulations – Hawkins Celebrates Employee Promotions

Chloe Duggan — Tue, 07 Apr 2026 07:30:12 +0000

It is with great pleasure that we announce a series of well-deserved promotions across our organisation.

Our newly promoted colleagues Ben Lister, Shimin Zhuang, Yang Dang, Ross Clarke, and Richard Baker, have consistently demonstrated outstanding technical expertise, professionalism, and a commitment to the highest quality standards. Their promotions recognise a sustained period of achievement across complex casework, advanced technical development, and active engagement in continued professional learning.

Beyond their case responsibilities, each has made significant contributions to the wider business, including leadership in Health & Safety, mentoring colleagues, and positively influencing best practice across their teams. Their strong performance in mentoring, diligence in maintaining quality standards, and sustained operational contribution have demonstrated the professionalism and quality that these roles require.

We extend our sincere thanks to each of them for their continued hard work, leadership, and positive influence across the business.

Please join us in celebrating the achievements of our newly promoted Senior Associates and Principal Associates. We look forward to their continued success and impact across the organisation.

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