What is hidden inside an old timber beam? Research into Circular CLT

From the outside, you see timber. Inside, however, an entire construction history may be hidden: a nail, a screw or the remains of an old connection. Within CirkHout, Urban Climate Architects, TNO and partners are investigating how existing timber can be reused at high value, including for Circular CLT. One question is key: what do we need to know about reclaimed timber before we can process it safely and effectively?

Existing timber carries its history with it

When building with new timber, the material is generally more predictable in terms of origin and condition. Reused timber is different. A beam taken from an existing building has already had a previous life.

Metal components can remain hidden inside the timber, even when they are no longer visible from the outside. Nails, screws or remnants of earlier connections can become important once the timber is sawn, machined or otherwise processed again.

That is why circular construction is not only about reuse. It also requires a better understanding of the materials that are re-entering the construction chain.

Looking inside timber with CT scanning

Within CirkHout, the team is exploring how CT scanning can help detect hidden metal components inside reclaimed timber.

The scan is not the goal in itself. The information it provides can help determine how the timber should be prepared and processed next. Where are potential obstacles located? Which parts require additional attention? And what is the most responsible next step?

This makes material investigation an important part of the design and reuse process. Before existing timber can take on a new function, we first need to understand what we are actually working with.

From reclaimed timber to Circular CLT

The research connects directly to our wider work on the high-value reuse of timber. Within CirkHout, Urban Climate Architects, TNO and partners are examining how existing timber streams can be reused for circular timber construction, including C-CLT.

With Circular CLT, the focus is not only on timber’s structural potential, but also on how existing resources can remain in the construction chain at the highest possible value for as long as possible.

This links directly to our work as a mass timber architect and to our broader activities in research and innovation. Reuse does not start with the question of what we can do with waste. It starts with understanding the value that is still present in existing material.

Material knowledge as a basis for circular design

The history of an old timber beam does not have to be a problem. But we do need to understand that history.

By investigating reclaimed materials more carefully, we can create a more reliable basis for circular design, biobased construction and timber architecture. This helps determine which materials can be reused, what preparation is required and where they can be given a new high-value application.

That is what circular construction requires: not simply reusing a material, but first understanding it, learning from it and then designing with it responsibly.

Read more about Circular CLT made from waste wood or discover what biobased construction means.

For more information, please contact UC Architects or view our projects.