Manufacturing advanced timber frame structures from home-grown timber presents some special challenges.

Softwood grown in our mild climate has a low density but a good proportion meets the C16 strength grade. Some may do better but it’s doubtful if we really need it. For the sort of buildings we tackle day to day, C16 is perfectly adequate provided the basic components remain stable.

Engineering consistent components from material which has a tendency to twist as it dries is the key to greater utility of home-grown softwoods in my opinion. It is technically feasible to use systems based on stick build or studded frames but it can be wasteful.

Producing industrial-scale glulam or LVL, the obvious solution, is beyond the scope and resources of the forest industry in Wales and probably the UK. Any solution has to be tailored to the properties of the raw material and the capacity of the industry if it is to have a reasonable prospect of acceptance.

Four years ago a group of interested parties – public, commercial and academic – embarked on a project to develop a housing system which could use home-grown spruce as its main structural component.

In the course of developing the system, now known as Ty Unnos, it became clear that the principal components, box beams made from C16 carcassing timber and ladder beams from side boards from the same logs, had greater capacity than expected. They had the potential to adapt to other building systems and to enable Ty Unnos to be used in applications beyond the rural housing called for in the original project brief.

We’re are now at the stage where the study is nearing completion, with TRADA writing up the European Technical Approval, while commercial partners have already brought a fully certified system to market.

Having overcome the challenges, can we now develop the opportunity to exploit the very low thermal conductivity of home-grown softwood? Could its perceived weakness actually be its strength as we strive for buildings with higher thermal performance?

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