What do the latest changes mean for building with CLT?

Buildings are the sum of many parts and we need a full portfolio of materials to achieve the best outcomes in terms of, performance, sustainability, safety, durability, efficiency and cost. Since the new Building Regulations came into force on 21st December 2018, much has been written about cross laminated timber. Here Andy Goodwin shares how B&K Structures have taken a pragmatic approach to embrace the new protocols.


&K Structures are not engineered timber purists. Our business model focuses on hybrid construction solutions – however, CLT is by far the most exciting revolutionary building material of the 21st century and will be significant in our future development plans. Only now are we truly realising the full capabilities of this strong, sustainable and technically-advanced structural solution and the new regulations will not stifle innovation.

The UK has a magnificent heritage of timber architecture dating back to the 13th century. We are now building on this legacy using groundbreaking engineered timber systems. We develop high-quality, low-carbon projects for a wide range of clients throughout the UK and through our robust, integrated supply chain, B&K Structures are dedicated to finding the best solution.

Putting the changes into perspective

Changes in the Building Regulations have restricted the use of engineered timber in the external wall elements over 18m, that is circa six-storeys. To put the changes into perspective, we have constructed in excess of 50 cross laminated timber projects over the past 15 years, of which only three would have felt the impact of the regulatory change and a cost neutral wall solution would have been simple to implement.

The engineered timber sector, by its very nature, is founded on innovation – we are pioneers of sustainable construction and with modifications, B&K Structures will ensure building highly sustainable CLT structures over six-storeys is not only possible but also highly practical.

The restriction applies to the external walls of residential accommodation, care homes, hospitals and school dormitories over 18m. The rest of the building including internal walls, floors and roof can therefore be formed in CLT. This equates to approximately 80-90% of the overall structural frame.

In anticipation of the Government announcement, we have been working in close collaboration with our supply chain partners to develop alternative through-wall solutions that can be implemented with a primary CLT superstructure.

Our non-combustible unitised wall panel systems have been developed with leading industry supply chain partners. The systems replace the cross laminated timber elements from within the external wall line with a hot rolled structural steel carrier frame and non-combustible SFS infill wall panels, the remainder of the structural frame will be constructed in CLT, which is totally compliant with the regulatory changes.

As part of the research and development of these compliant solutions, careful consideration has been given to the design interface between the CLT superstructure and the SFS walling system. The SFS system and associated connection details have been designed to take in to account increased load cases attracted by traditional brickwork, heavier brick slip systems and balcony locations. Importantly the system is cost and programme neutral.

We have been instrumental in the development and growth of the CLT market in the UK, and through continued collaboration with our supply chain and industry stakeholders, this will continue. The latest Building Regulations merely change the way we construct the external walls to residential schemes above 18m. We will continue to work with our clients to ensure that any new projects are designed and delivered in accordance with the new Building Regulations.

Over the last 10 years, CLT has been emerging as a sustainable and cost-effective building material of choice and a vital component in the battle to reduce carbon emissions in the construction sector. We must consider the specification of materials when constructing large scale developments to ensure we minimise the impact on the environment, not just for us but for the health and wellbeing of generations to come.

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