Glulam (glued laminated timber) and CLT (cross-laminated timber) are spreading fast worldwide as a sustainable alternative to concrete and steel. In these elements the adhesive is an integral part of the load-bearing structure.
What are glulam and CLT?
Glulam: beams and columns made by bonding lamellas with their grain parallel. They span long distances and can be curved.
CLT: solid panels with layers bonded at right angles, used for walls, floors and roofs.
Why 1C PU?
Structural timber has traditionally used melamine-urea-formaldehyde (MUF) and phenol-resorcinol (PRF) glues. One-component PU prepolymers now offer major advantages:
- Formaldehyde-free: important for indoor air quality and green certification.
- Light-coloured glue line: an aesthetic plus on exposed timber.
- No mixing: a single component reduces the risk of error.
- Low application weight: high strength with less adhesive.
- Fast press times: cures at room temperature with no heating.
Points to watch
- Wood moisture: usually 8–15%; moisture is needed for curing but too much can cause foaming.
- Surface preparation: bond lamellas soon after planing.
- Press pressure and time: follow the manufacturer's instructions.
- Approvals: adhesives for structural use must be approved to the relevant standards (e.g. EN 15425).
Sustainable construction
Wood stores carbon as it grows, and buildings in structural timber significantly reduce their carbon footprint. The right adhesive ensures they serve safely for decades.
Contact us for technical support on your structural timber projects.
