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In 2021 EURBAN contributed to a cost analysis by Cost Consultant Turner Townsend and one of our supply chain partners, CLT manufacturer Stora Enso which aimed to demonstrate that a solution with mass timber is cost competitive when compared to other construction methods. The majority of schools used for the analysis were steel frame, details of which were provided by Turner Townsend. EURBAN used Histon & Impington Brook Primary school by Frank Shaw Associates as an example of a mid-sized school that can be replicated. Cost-wise the research used schools ranging from low to high end. Of the Government Framework procured schools, Histon & Impington sits in the mid-range.
The research shows that there needs to be an understanding of how the cost is built up. The pot of money is identical for different building methods, but the difference is the way it is divided up. The critical factor for schools is ‘time’ because handover dates are restricted by term times and are rigidly fixed to once a year. If the programme is a month late the school may have to delay the project till the following year. We have proven that mass timber is cost competitive, but the critical point is that building with mass timber results in savings on the programme due to its speed of construction and reliability. This security on the programme is the key point. A standard school with a steel frame and perhaps pre-cast concrete planks requires more trades whereas with CLT first fix can go straight in as soon as the frame is up.
It’s also important to understand with a cost comparison that the costs you are analysing are just a snapshot of that time. The aim with the Turner Townsend & Stora Enso research was to demonstrate that the cost is comparable and competitive; the cost is the same but it is the build-up of the cost that is different. A QS will often think that a CLT frame will cost a lot more than a steel frame, but may have only included columns, beams and perhaps the floors in his steel frame costs. With CLT more elements are included such as internal and external walls and stairs. It’s vital to understand the cost build up and the potential savings for example on foundations, programme and prelims. This is what you want to demonstrate – it’s not just cost per square metre of the structural elements such as walls, floors and roof, it’s the overall cost of delivering the building. Of course if someone has used CLT and EURBAN’s services previously, say at Kier Eastern, they already know that although they could possibly procure it for less CLT is faster and EURBAN is a reliable partner so it makes total sense for their programme.
One of the barriers that still exists when it comes to building mass timber schools instead of the more traditional steel or concrete frame structures is that of perception. For many main contractors there is a lack of knowledge and understanding about mass timber as well as an element of fear of the unknown. The thinking remains ‘we’ll do what we’ve always done – why should we change?’ There are some technical points such as fire, moisture and thermal mass, but mainly it is down to understanding. People who don’t know CLT sometimes think it’s the same as timber frame and don’t understand its superior structural capabilities. They may assume such wide spans will need to be formed of steel, so the differentiation also needs to be made between timber frame and mass timber to show how large open plan spaces can be created.
Then there is the drive from DfE and others on the need for low and zero carbon solutions. With timber we have a sustainable and renewable material and I would like to move the discussion away from being solely about carbon to timber’s overall sustainability. This is where I feel timber has the benefit: the fact that it is renewable and therefore it is part of the solution for our limited natural resources. If we really want to become a low carbon society the best place to demonstrate it is in schools where children are learning – not just about the structure, but what it means to run a building with heating, electricity water etc.
With mass timber we don’t need to create huge offsite factories, we have an existing large and growing supply chain which is scalable and that’s the most important thing, we have a scalable solution that is not supplier specific because CLT and glulam are more or less the same from every supplier. Mass timber is very adaptable and with it we can build any kind of school; with education buildings the spectrum is huge, but the building will always be used for the same purpose of teaching and learning be it nursery or university. I feel that we have already a very good option for low or zero carbon buildings by using mass timber. It isn’t the only option, but it is a part of the solution, and it is already available for a large number of the future buildings.