A new year, built on possibility
There’s something about the start of a new year that invites reflection. A pause. A moment to look back at what’s been achieved and ahead to what’s possible.
At Castellum, that sense of possibility is what drives us every day.
Construction, for us, has never been purely about the physical build. It’s about trust, clarity and confidence – knowing that your vision is understood and that every decision is made with care. Whether delivering a highly complex luxury residence or a more tightly defined brief, our approach remains consistent: thoughtful planning, exceptional craftsmanship and a seamless experience from start to finish.
Heritage, retrofit and ambition
Alongside this, retrofit has become an increasingly important part of our work. We bring extensive experience in upgrading existing buildings for the future – carefully balancing conservation, performance and sustainability. This approach was recognised in late 2025, when Claridge House was awarded Winner: Conservation, Decarbonisation and Future Re-use at the Architects Journal Retrofit and Reuse Awards. The project stands as a testament to what can be achieved when heritage, environmental responsibility and craftsmanship are considered together (see case study below).
We also have significant experience navigating today’s increasingly complex regulatory landscape, including the delivery of High-Risk Buildings and the requirements of Gateway 3. Our teams are well-versed in managing compliance, coordination and technical assurance at the highest level – ensuring safety, quality and programme certainty are embedded throughout the construction process.
Case study: A collaboration in action
What truly sets Castellum apart, however, is the depth of expertise we hold in-house. We have a fully qualified Retrofit Co-ordinator and an in-house design team of qualified architects, working closely alongside client-appointed teams. This allows us to support projects at any stage of design development, helping to refine, resolve and realise a client’s vision – whether we are engaged early in the process or brought in once designs are already well advanced. It’s a collaborative, informed approach that adds value, clarity and confidence throughout delivery.
From contemporary architecture to historic restoration, intelligent retrofit and highly regulated schemes, we pride ourselves on navigating complexity with confidence – ensuring every project is delivered with discretion, rigour and care.
Castellum Studio
Castellum Studio Castellum Studio was created to support clients who want the Castellum experience, but for projects with a smaller overall budget. It allows us to bring the same expertise, rigour and attention to detail that define Castellum, applied at a different financial scale – without compromise in quality or approach.
Cost awareness and disciplined project management sit at the heart of everything we do. Castellum Studio simply offers a structure that is proportioned to suit projects where scope and budget are more modest, while still benefiting from the knowledge, processes and craftsmanship of the wider Castellum team.
The result is a service that feels considered, refined and reassuring – regardless of scale.
Ongoing care and long-term relationships
Castellum Studio also enables us, as a business, to offer a dedicated aftercare service across our projects. This ensures that once a project is complete, our clients continue to receive the same level of attention, responsiveness and expertise.
From addressing post-completion requirements to supporting the long-term performance of a home, our aftercare approach reflects our commitment to lasting quality and enduring relationships – because our involvement doesn’t end when the build does.
Looking ahead
As we move into the new year, we would like to wish all our clients, consultants and industry contacts a very happy and successful year ahead. We’re grateful for the relationships we’ve built and look forward to continuing those partnerships in the months to come.
If you’re considering a project – whether ambitious in scale or carefully calibrated in scope – we would be delighted to talk. Please do get in touch to discuss how Castellum or Castellum Studio can help bring your plans to life.
Here’s to a year of thoughtful choices, beautifully executed.
Claridge House case study
THIS PROJECT HAS PASSED GATEWAY 3
In October 2024 Castellum was awarded a design and build contract for the refurbishment of two levels of Claridge House, Davies Street, London. This project was within an existing six storey building and the works were for the change of use from commercial office units to domestic apartments on levels one and two.
Lee Boileau – Project Director, Francesco Paparo – Design Manager and Dewi Scourfield – H&S advisor, worked closely on the scheme to ensure it was delivered in full alignment with planning requirements, building regulations, the fire strategy and all health and safety obligations, while maintaining the highest standard of quality expected by the client, Grosvenor Estates.
In March 2024, the project underwent a significant transition with the appointment of a new Building Control Officer from an approved inspector to Westminster City Council. As a result, Claridge House became subject to the BSR Gateway Process – the pre-construction ‘stop/go’ checkpoint introduced under the Building Safety Act (BSA) 2022 for Higher Risk Buildings (HRBs). This regulatory shift presented considerable challenges, particularly because several new compliance requirements and supporting documentation had to be incorporated while the works were already progressing on site. To navigate this effectively, Castellum maintained consistent communication with the newly appointed inspector, facilitating multiple site meetings to ensure every comment, query and compliance action was addressed promptly and comprehensively; ensuring all relevant drawings, submittals, fire stopping schedules, site progress reports and photographic records where meticulously saved and adhered to. The project incorporated many renewables – air source heat pumps, solar panels, green roofs and diathonite plaster to name a few – which each having its own technical issues, to work alongside the existing structure, fire strategy, communal gas boilers and heating system. These complexities were coupled with the fact that it was an occupied building and site access was via a scaffold only.
Claridge House, as a higher risk building, is subject to the prescriptive requirements of Regulation 7 of Approved Document B, which mandates the use of non-combustible materials within external wall systems. To support compliance, a full suite of technical documentation was provided, including fire certification for the lime plaster applied to the external walls, insulation materials, door and window systems, fire compounds, and all relevant wall and slab penetrations.
Project Manager: Jackson Coles
Principal Designer: Studio PDP
Client Team: Grosvenor Estates
Building Control Officer: WCC
Fire Engineer: Hoare Lee
Structural Engineer: Elliot Wood
M&E Designers: Harley Haddow
Health and Safety matters – including access strategies, maintenance considerations and construction-stage risk management, were regularly reviewed in collaboration with the Principal Designer and the Health and Safety Director at Studio PDP, ensuring full compliance with statutory obligations throughout the project lifecycle.
In 2025 this project won an award at the Architectural Journal Retrofit and Reuse Awards for Conservation, Decarbonisation and Future Re-use.
On learning that Claridge House had won the award Francesco said, ‘This achievement stands as a testament to Castellum’s expertise, commitment, attention to detail, client-focused approach and pride in their work. It is a powerful combination and one that very few contractors in the market can genuinely claim’.
Lee Boileau, Castellum’s Retro-fit Co-ordinator and Project Director for Claridge House was at the awards with Francesco and was thrilled by this award. Lee has been instrumental within Castellum for ensuring that, as a main contractor operating in super prime London, our company has the credentials, ability and passion to deliver sustainable projects of this calibre.
Claridge House is an icon now for London and every major city and demonstrates how top luxury apartments can be delivered in existing buildings, targeting net zero carbon emissions. This project has paved the way for all ambitious developers aiming to have sustainable luxury projects in their portfolios and the Castellum team have the expertise to make this possible. This work was done in a Conservation Area in Mayfair (with the very strict planning conditions that come with it). Luxury finishes were applied to a high-risk building (higher than 18m and therefore subject to restrictive fire regulations) achieving Net Zero Carbon, requiring specific knowledge to complete thermal efficient details, integrate and install passive and active thermal control systems (MVHR, solar panels, etc).
