Modern Methods of Timber Construction
Contemporary craft and technology; and the case for home grown timber
Modern timber frame construction lies at the heart of our practice at Hiraeth Architecture. It reflects a synergy in our work between natural, locally sourced materials and highly efficient, low-energy construction.
Our approach is guided by a desire to minimise carbon, waste and energy loss – achieved through sustainable manufacturing and contemporary building methods.
Timber Construction
Despite increasing mechanisation, craftsmanship remains central to our work. We are privileged to collaborate with some of Wales’ finest makers — and we’re pretty handy ourselves.
Over the years, the use of homegrown timber and offsite manufacturing has been a key focus of our learning and practice. A significant part of Rob’s career has been dedicated to exploring and advancing this area. Working closely with industry partners, we’ve participated in a range of research and development projects that have shaped new products, systems, and construction methods.
The Case for Homegrown Timber
Timber use in new home building has risen from just 14% in 2007 to nearly one in three homes today. While this is progress, it remains well below the European average, especially in non-residential sectors.
This shortfall is perhaps understandable given that Wales has one of the lowest woodland covers in Europe—just 15%. Between 2010 and 2019, that grew by only 6,000 hectares (1.9%), despite Wales declaring a Climate Emergency during that period.
Approximately 80% of timber used in the UK is imported from northern Europe and Canada. These colder climates produce slow-grown timber with greater density, stability and strength. By contrast, Wales’ most commonly available home-grown timber, Sitka Spruce, is often described as too knotty, prone to twisting, and fast grown to be used in mainstream construction.
Although initiatives have spotlighted Sitka Spruce’s potential, the industry continues to rely on imported timber. Meanwhile, homegrown softwood, typically graded as C16, is often relegated to lower-value uses like fencing, pallets, and chip for board products. While C16 is suitable for many structural applications, it is often overlooked for many structural applications, preferring the higher specification of C24 – inadvertently excluding local resources.
A Vision for a Forest Nation
We share a vision with many of the exceptional organisations we collaborate with – including WoodKnowledge Wales and Coed Cymru – that Wales can become a Forest Nation, characterised by increased forest cover and a thriving, sustainable timber industry.
This transformation has far-reaching potential. It can strengthen the Welsh economy, enhance biodiversity, support leisure and tourism, enrich education, and directly address the Climate Emergency. Tree planting is central to this vision, but it must be underpinned by strong and consistent demand.
As construction professionals, we have a vital role to play in demonstrating the value of Welsh timber through the delivery of healthy, efficient, high quality, and affordable buildings with low whole-life carbon impact. At the same time, we must contribute to establishing the skills and knowledge required to realise this future.
Our design approach reflects this aspiration. We adopt a ‘timber first’ mindset and prioritise the use of homegrown timber wherever feasible.
Through strong partnerships with Welsh manufacturers and contractors, we’ve developed innovative methods of timber construction – many of which are featured in our portfolio. These partnerships allow us to offer complete building solutions, from component systems assembled on site to fully fabricated offsite units delivered as near-complete buildings.
Research and Affordable Housing
The use of timber – particularly homegrown timber – in affordable housing has been a central focus of our research over the past 15 years. This began with the collaborative Ty Unnos project (‘a housing in one night’) and continued through our involvement in the Wood Knowledge Wales-led ‘Home grown Homes Project’.
Between 2019 and 2021, we led a work package titled Zero Carbon Homes – Zero Carbon Timber Solutions for Wales. This study examined what ‘zero carbon’ means for the affordable housing sector, drawing on insights from leading initiatives such as LETI. We explored how these aspirations could be translated into practical and measurable outcomes for both embodied and operational carbon – within a sector that is exceptionally cost-sensitive and lacks the design resource to model and implement low-energy low-carbon strategies.
Adopting a fabric first approach, the study evaluated a range of timber-based solutions capable of meeting demanding performance targets. We subsequently demonstrated how key housing typologies could be designed and calculated to achieve a zero-carbon specification, using locally available resource and construction systems. We are delighted that this work has helped to inform and stimulate the ambitious Tai ar y Cyd project.
Ty Unnos – a house in one night
Ty Unnos, meaning ‘a house in one night’ began in 2007 as a collaborative research initiative between Coed Cymru, the Welsh School of Architecture, and several commercial partners. It explored the structural use of homegrown Sitka Spruce, and formed the basis of Rob Thomas’ PhD with the WSA’s award winning Design Research Unit Wales.
Working with Kenton Jones Joinery and others we designed, fabricated and prototyped a suite of high-performance structural components made from homegrown spruce. These components were designed for offsite fabrication and particularly suited for application in affordable housing.
The Ty Unnos system as a kit of components has since been tested and deployed across a wide range of projects. To further improve scalability, consistency, and affordability, the collaboration shifted toward volumetric construction – producing modular homes within a factory setting. This approach reduces waste and travel, strengthens local supply chains, and ensures quality, employing all manufacturing capabilities within the Kenton Jones Ltd group.
A successful bid to the Welsh Innovative Housing Programme enabled development of six low-energy homes for Isle of Anglesey Country Council. The project, known as Tre Ifan acted as a catalyst for the next technical evolution of Ty Unnos implemented by Unnos Systems within a purpose-built factory in Welshpool, Powys.
One of the most distinctive applications of this technology is Koto House developed Koto Design for the remote island of North Uist. Designed to Passivhaus standards, the building far exceeds UK regulations for airtightness and thermal performance.
Unlike many modular systems that rely on steel for structural stiffness, our approach uses an all-timber frame of bespoke engineered timber box beams, filled with cellulose insulation. The result is a low-embodied-carbon, thermally efficient fabric with minimal thermal bridging. Constructed entirely within a factory, this approach was especially valuable in delivering a high-quality product to the Isle of Uist, one of the UK’s harshest building environments.
Warranties, Testing & Innovation
We also take a proactive role in addressing one of the main barriers to widespread timber use: lack of certified, insurable construction details. By designing and prototyping low-carbon wall build-ups, we enable testing and certification pathways essential for warranty approval. This empowers developers to choose sustainable, climate-conscious materials without compromising on risk or cost, helping drive systemic change toward a decarbonised construction industry.
If you’d like to learn more about our timber construction methods or have a project you’d like to discuss, we’d love to hear from you: Hi@hiraetharchitecture.co.uk
To read more about our collaboration with specialist volumetric manufacturer Unnos Systems take a look at Tre Ifan and Koto House.