Koto House | North Uist, Outer Hebrides

Technical Architect for Koto Design’s sculptural modular timber home

Koto House | North Uist, Outer Hebrides

Technical Architect for Koto Design’s sculptural modular timber home

On the Outer Hebridean island of North Uist, Koto House is nestled within an 11-acre site, overlooking a tidal lagoon fed by the North Atlantic.

Designed to harmonise with its dramatic surroundings, this sculptural, modular home is the result of a collaboration between Koto Design, Hiraeth Architecture, and timber construction specialists Unnos Systems. The project showcases the practice’s ongoing development of homegrown Welsh timber systems, delivered as prefabricated, high-performance modules and demonstrates the exceptional innovation and quality possible within the Welsh timber and offsite construction industries.
Description

Manufactured and substantially finished in Welshpool, Powys, Koto House was shipped in seven prefabricated modules, travelling 570 miles across land and sea, to the remote and extraordinary Hebridean island of Uist. Set on the breathtaking shore of a tidal lagoon fed by the Atlantic Ocean, the home faces the full spectrum of a challenging and unpredictable climate.

With a population of approximately 1300 people and accessed by boat or plane, the island of North Uist is a challenging construction environment not just for its extreme climate, but for its limited workforce, trades and access to building materials. Delivering a low energy, sustainable and highly crafted contemporary home within this context is a formidable and substantially unexplored challenge. Developed by modular design specialist Koto Design, the proposal is a striking contrast to the vernacular of low eaves white rendered masonry cottages. The home’s roofscape mirrors the undulating coastline whilst its black monolithic appearance harmonises with the black rocks of the shoreline and the dense woodland backdrop. The project both conceptually and technically is exceptional!

The project is the first private dwelling of the Koto collaboration, with Unnos Systems and Hiraeth Architecture appointed to technically resolve and deliver the project in partnership with Koto Design and Koto Living.

Detail

As Technical Architect for the project, our focus was on the detail of the built fabric, ensuring that carefully designed and specified junctions and materials would deliver both the sustainable aspirations and the aesthetic vision of Koto Design and the client. The challenges posed by the context required exceptional planning and technical accuracy. The house was designed to the millimetre, with both the height and width of the modules strictly constrained from the concept stage to fit the ferry’s capacity. All materials, skills, products, and tools had to be in place for the 600-mile journey or transported to site from the mainland, including heavy plant—subject to the risks of bad weather, ferry cancellations, and Covid—and ready for assembly in just one day. The result, however, is an exceptional piece of architecture for the island.

The house is composed of a pair of sleeping and service wings connected by a spacious central open-plan living area. Elements are oriented towards key views and connections with the expansive landscape, framed by oversized, unbroken windows with integrated seats and nooks that create intimate sanctuaries. The thoughtful design fosters a continuous yet structured connection with the exterior, reinforcing the home’s purpose as a sanctuary, no matter what the weather brings. Wrapped in a seamless envelope of scorched larch timber cladding and black zinc, the two-storey and mono-pitched forms create a sculptural silhouette that echoes the fall of the land and coastline. Inside, integrated furnishings, floor finishes, textiles, and natural pigments harmonise with the landscape.

Koto House builds on over a decade of collaboration and innovation in the use of homegrown timber and follows the approach of the Innovative Housing Programme-funded Tre Ifan Housing Scheme for Isle of Anglesey County Council. The system adopts an uncompromising approach to structural stability, airtightness, and thermal performance. Uniquely within volumetric or modular construction, timber is used throughout, with an intentional rejection of steel to achieve structural stiffness, reduce thermal bridging, and lower embodied carbon, while also minimizing construction defects.

The project aims to deliver a net-zero construction solution by addressing carbon emissions in the design, manufacture, and delivery of the house, considering both operational and embodied carbon. A high-performance fabric delivers Passivhaus-level airtightness and insulation, including triple glazing and significantly reduced thermal bridging. Intelligent window placement and orientation optimize solar gain, while a whole-house mechanical ventilation system with heat recovery further reduces operational energy demand. This is supplemented by simple, all-electric heating and hot water systems, resulting in an EPC rating of 93A.

Reducing embodied carbon has been a core priority for the project team. The primary structure is made from bespoke engineered timber box beams combined with timber-based infill panels, all insulated with recycled cellulose and using homegrown Douglas Fir, Sitka Spruce, and Larch throughout. Carbon-intensive groundworks are minimized by the use of suspended timber floors. Both external and internal finishes incorporate timber and timber-based products wherever possible, minimizing carbon-intensive wet trades. These strategies are maximized through careful management of the design and manufacturing process, evolving details and systems with each project to minimize waste, eliminate inefficiencies and defects, and shorten supply chains.

Summary

Koto House stands as a showcase of offsite timber design and construction, overcoming the challenging conditions of North Uist to deliver a sustainable, high-performance, and architecturally striking home. The collaboration between Koto Design, Hiraeth Architecture, and Unnos Systems demonstrates the power of innovation in modular design and homegrown Welsh timber systems. The project not only reflects a deep respect for its extraordinary surroundings but also pushes the boundaries of offsite construction, offering an exceptional response to both environmental and logistical challenges.
The house’s seamless integration with the landscape, its sustainable materials, and the technical precision involved in its construction make it a model for future offsite, low-carbon, and highly crafted architecture. 

Category
New Build Residential
Status
Completed 2022
Location
North Uist National Scenic Area - Claddach Valley, North Uist
Team
Architects Koto Design
Koto Living
Kenton Jones: Woods of Wales
Paramount Structures
Recognition
Wood Awards – Research And Innovation Winner 2024
Wood Awards – Private Residential Shortlisted 2024
Category
New Build Residential
Status
Completed 2022
Location
North Uist National Scenic Area - Claddach Valley, North Uist
Team
Architects Koto Design
Koto Living
Kenton Jones: Woods of Wales
Paramount Structures
Recognition
Wood Awards – Research And Innovation Winner 2024
Wood Awards – Private Residential Shortlisted 2024
Category
New Build Residential
Status
Completed 2022
Location
North Uist National Scenic Area - Claddach Valley, North Uist
Team
Architects Koto Design
Koto Living
Kenton Jones: Woods of Wales
Paramount Structures
Recognition
Wood Awards – Research And Innovation Winner 2024
Wood Awards – Private Residential Shortlisted 2024
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Heritage Surveyor & Administrator
BSc(Hons) MSc

Alice studied Quantity Surveying and Commercial Management at the University of South Wales. In 2022 she then completed a Masters in Architectural Conservation at the University of Edinburgh, which gave her a specialist knowledge of architectural history an understanding of traditional building techniques. Her dissertation addressed the use of Oral History as part of Architectural Conservation, fuelling her particular interest in sustainability and folk studies.

Alice joined Hiraeth Architecture in 2022 and is now applying this varied background to undertake the role of Heritage Surveyor. Her work includes Quinquennial Inspections for Monmouth and Llandaff Diocese, Conservation Management Plans and background, archival research on projects which include historic buildings or are sited within historic contexts.

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We recognise our impact on the planet and the damage that construction and buildings-in-use can have. A thoughtful approach to siting and orientation, built fabric, passive measures, materials and methods of construction is key to our way of working.

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Trust, collaboration, respect and integrity are critical to the work we specialise in and the clients we seek. The industry is often a challenging environment, but we collaborate with manufacturers, contractors, consultants, and of course our clients, to challenge one another to realise the best possible outcomes.

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We arrive at our solutions after a rigorous analysis of the social, environmental, political, geographic and historical characteristics of the project. Each project and solution is distinctly different – deeply rooted in its context and unique place in this world. Context is everything.

Nicki Spiteri

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Nicki, our fantastic Office Manager, joined the company in 2023 and plays a vital role in keeping the team organised and on track. She brings a well-rounded skill set, with experience in both the architecture and construction industries, ensuring the efficient running of the practice so everyone can focus on what we do best. Nicki is committed to fostering positive, trusted relationships with clients and consultants alike and serves as a reliable point of contact for any queries or concerns.

Hannah Cummings

Architectural Assistant

BA (Hons), MArch

Hannah is one of our Welsh School of Architecture contingent, having completed her Masters degree in 2021. During her studies, she explored contrasts within housing developments and how these reflect economic and social status culminating in a thesis on social supported living environments in the context of Dolphin’s Square, Westminster.

Her academic studies has shaped her interest in social housing and the relationship between psychology and living conditions. She also is particularly interested in the use of local (Welsh) skills and materials in architecture and construction, reflecting her commitment to sustainable, regionally inspired design.

Before joining Hiraeth in 2023, Hannah gained experience at the award winning practice Hyde + Hyde, contributing to a portfolio of high-end private residential projects. Now working as an Architectural Assistant, she is pursuing her RIBA Part 3 Diploma in Professional Practice while contributing to a range of community and residential projects, including the extension of Sant Y Nyll House and Pontneddfechan Community and Visitor Centre.

Alice Smith

Heritage Surveyor

BSc(Hons) MSc

Alice brings a unique skill set to the team, offering specialist expertise in architectural history and building conservation. She initially studied Quantity Surveying and Commercial Management at the University of South Wales but, inspired by her involvement in local church conservation, pursued a Masters in Architectural Conservation at the University of Edinburgh. This renowned programme provided her with in-depth knowledge of architectural history and understanding of traditional building techniques from first principles. Her dissertation explored the use of Oral History in Architectural Conservation, sparking a lasting interest in sustainability and folk studies.

Alice joined Hiraeth Architecture in 2022 and now applies her diverse background in her role of Heritage Surveyor. She has extensive experience conducting condition surveys, quinquennial inspections, and preparing Conservation Management Plans. Recent projects include Conservation Management Plans for Swansea University Wallace Building, Singleton Abbey, Swansea University’s Original Library, and the Grade 1 Listed Scheduled Ancient Monument of Oystermouth Castle. Alice also provides a valuable resource across the design team, leading historic and archival research while contributing to significance and heritage impact assessments. 

James Lawley

Project Technologist

HNC

Before joining Hiraeth Architecture James worked with several design led practices, both large and small, across the South West and South Wales.  During this time he gained valuable experience within a range of design sectors, including Masterplanning, Urban Design, Architecture and Specialist Conservation projects. Working within a comprehensive range of projects has resulted in an overarching and proficient portfolio, combining specialist expertise with robust, all-round competency.

James joined Hiraeth Architecture in 2021 and has since supported the team across a variety of projects spanning all RIBA Works Stages. Through the diverse range of projects at Hiraeth, James has cultivated a strong interest in the developing and applying traditional detailing and construction methods in the delivery of contemporary architecture, thoughtfully integrating advances in building technology, craftsmanship and sustainable low-energy design principles.

In addition to his comprehensive knowledge of technical software and Building Information Modelling, James serves as a technical lead. He recently led the technical design for Millers Place, a 100% affordable Passivhaus development of 40 apartments in Welshpool, and the conversion and renovation of Pond Cottage in Gnoll Park. James plays a key role in project delivery on-site, including Penllegare Visitor Centre, the reconfiguration of St Cleers church in Somerset and the extension of a primary school in Usk.

Carl Williams

Project Technologist

BSc(Hons)

As one of the original members of the Hiraeth team, Carl joined the practice in 2020, contributing extensive technical knowledge and experience aligned with the company’s specialisms, including both innovative modern methods of timber construction and traditional building techniques. He plays a key role in the team’s use of Building Information Modelling (BIM), encompassing collaborative 3D modelling and CAD / CAM processes.

Carl studied Architectural Design and Technology in Cardiff Metropolitan University, where he developed a strong interest in sustainable design and the importance of precise, well considered detailing to successfully realise architectural visions.

Throughout his career, Carl has contributed to a diverse range of projects, across all RIBA Work Stages. He has gained extensive expertise in specialist conservation work including direct involvement in securing statutory permissions for Planning and Listed Building Consents and administering construction contracts. His recent projects include the technical design and delivery of a new Visitor Centre for Gnoll Park and a modular timber house on Uist Island in the Outer Hebrides.

Chloe Sambell

Project Architect

Bsc(Hons) MArch(Hons) DipArch RIBA ARB

Chloe is a qualified Architect with SPAB conservation training, joining Hiraeth in 2019. Since then she has lead several key projects in the office across all RIBA work stages and been integral in securing consent for a number of particularly challenging projects. These include the re-envisioning and transformation of the under-used yard to the Grade II Listed Tramshed building in Cardiff and the extension to the Grade II Listed Capel y Groes in Cilycwm.

Chloe’s passion lies in user-centric design, and a carefully researched understanding of place. She combines rigorous problem solving with creative exploration to produce architectural solutions that enhance the special qualities and character of a site, giving careful consideration to each moment the building can offer – such as a view, the quality of light or the touch of materials.

She completed her Masters in Architecture with Distinction at the Welsh School of Architecture and was awarded the T Alwyn Lloyd Memorial, Foulkes Memorial and Wyn Thomas prizes. She has enjoyed returning to the school to support teaching in the second and fifth year studios and the Master of Urban Design course. More recently she also overseen the renovation of her own home, bringing her design philosophy into a personal context.

Dr Rob Thomas

Director + Passivhaus Certified Designer

BSc(Hons) MArch(Hons) PhD DipArch(Hons) RIBA ARB

Rob set up Hiraeth Architecture with Michael Plageman in 2019, to focus on the design and development of innovative timber architecture. Although always interested in timber based design and making, this interest took form during his time at the Welsh School of Architecture, where he worked with the university’s Design Research Unit Wales and Welsh woodland charity Coed Cymru to deliver a co-sponsored, design-led PhD, which he completed in 2011. His research explored innovative timber technologies using homegrown Welsh Sitka Spruce, with a focus on the application of modern methods of timber construction to the delivery of affordable housing. This work contributed to the development and certification of construction components and systems and the delivery of several award winning buildings, earning commendation in the RIBA President’s Awards for Research.

As a certified Passivhaus Designer, Rob integrates technical expertise with his passion for innovative and sustainable homes. At Hiraeth, he has delivered benchmark projects such as Tre Ifan and William Ainge Court, both affordable housing developments meeting Welsh Design Quality Requirements and Lifetime Homes standards. Notably William Ainge Court was Hiraeth’s first project to achieve Passivhaus certification.

Throughout his career, Rob has led the design and delivery of new-build, alteration and conservation projects from conception to completion. His portfolio includes a high performance replacement dwelling in the Welsh Valleys, a prefabricated large-span oak visitor building for the scheduled ancient monument of Cleeve Abbey, and visitor centres in Gnoll Park and Pontneddfechan. Beyond applied research in prefabricated system design, he has also led research studies into net zero whole life carbon housing for Wales and optimised retrofit strategies.

Since completing his studies, Rob has maintained close ties with the Welsh School of Architecture regularly contributing as an examiner, critic and tutor.

Michael Plageman

Director + RIBA Conservation Architect

BSc(Hons) BArch(Hons) DipArch MA DipCons(AA) CA RIBA ARB

Michael studied at the Welsh School of Architecture before completing the Architectural Association’s Postgraduate Diploma in Building Conservation in 2012. Combining academic study with over two decades of applied practice, he delivers a diverse skill set across all work stages and construction sectors, with particular specialisms in the conservation and management of change of sites and buildings of environmental, heritage, and communal significance.

Over his career he has established a broad portfolio of prestigious projects that includes conservation repairs and alterations to Chiswick House and Apsley House for English Heritage; new visitor centres within the Scheduled Ancient Monument of Raglan Castle and registered Historic Park and Garden of Penllergare Valley Woods; and the transformation of the grade II listed Kemeys Folly into a modern residence, featured on Grand Designs. Through his involvement in such prominent projects, he has demonstrated his ability to engage and connect effectively with the various communities and stakeholders who use and care for these important assets.

Michael is an active member for the Design Review Panel™, nationally providing impartial, constructive and expert design advice. He is a Quinquennial Inspector for the Llandaff and Monmouth Diocese, an elected member of the Monmouth Diocesan Advisory Committee, and also sits on the Archives Advisory Panel for the Royal Society of Architects in Wales. He founded Hiraeth Architecture in 2019, with fellow director Rob Thomas, applying his detailed knowledge of historic buildings with innovative new build solutions to embrace his interest in contextual design in the most sensitive of environments.

Jenny Clemence

Project Architect

BA(Hons) MArch PGCert ARB RIBA

Jenny joined Hiraeth in 2021 bringing extensive experience across all RIBA stages, with a particular focus on heritage, tourism, and community projects. Drawing from this background Jenny emphasises public consultation as a vital tool for understanding place and community needs, ensuring stakeholder values are embedded at the core of every project. Recently, Jenny led successful funding bids for the Gnoll Masterplan and designed new visitor facilities for Oystermouth Castle, to manage the changing needs of this Grade 1 Listed Scheduled Monument.

She studied at the University of Sheffield, earning a Distinction in her Masters degree, where her thesis and dissertation explored participatory design with homeless and displaced communities. Jenny has a strong interest in how well-designed spaces can transform social contexts, aiming to create a balance between atmosphere and functionality.

In 2018 she completed her RIBA Part 3 at the University of Nottingham. Since then she has returned to Nottingham as a visiting Collaborator with Studio 5A and has also worked as a design tutor at Loughborough University and a regular critic at the Welsh School of Architecture, enjoying the continued engagement with student design projects.

Jenny has worked with several design led practices in Wales and the North East gaining experience across multiple sectors for clients including the National Trust and Nottingham Trent University. Just before joining Hiraeth, she acted as design lead for a product start-up to develop and prototype a sustainable garden module addressing the rise in home working brought on by the COVID-19 pandemic, while aligning with key sustainability targets set out in the 2030 RIBA Climate Challenge (Commercial).