Laminating is the assembly of a product from layers bonded to one another, or the application of a thin facing or protective layer to a substrate. The individual layers are called laminations or lamellae; together they form a material with properties none of the layers has on its own.
Why layers?
Solid materials inherit their weak spots. A timber beam is only as strong as its largest knot or shake. Saw timber into thin laminations, cut out the worst defects and distribute the rest over the depth of the beam, and local weaknesses are averaged out. The result is stronger, more dimensionally stable and — above all — far more predictable than solid timber of the same size.
Applications in construction
- Glued laminated timber (glulam) — laminations typically 30 to 45 mm thick, all bonded with the grain running lengthwise, into beams, joists and trusses. It makes long spans and curved forms possible that could never be cut from one log.
- Cross-laminated timber (CLT) — layers bonded crosswise into panels that span in two directions and are used as wall and floor elements.
- Laminated glass — two or more panes with a PVB interlayer. When it breaks, the fragments stay bonded to the interlayer: safe against injury and, depending on the build-up, security or barrier rated.
- Sheet materials — plywood (crosswise bonded veneers), HPL laminate, melamine-faced board and MDF with paint carrier foil.
- Roofing membranes and foils — a multi-layer build-up in which each layer has its own job.
Points to watch
- The adhesive sets the service class. Not every bond is suitable for external or humid conditions. Check that the adhesive quality matches the service class the element will sit in.
- Timber moisture content. Laminations must be bonded at the right moisture content; timber glued too wet will let go later.
- Delamination is the failure mode. Layers separating announce themselves as hairline cracks in the glue line. In a structural element that calls for investigation, not a tube of sealant.
- Cutting removes the protection. Trim a glulam beam or a faced board and the core is exposed. Treat the new edge separately.
Related terms
- Glued laminated timber
- Cross-laminated timber
- Plywood
- HPL laminate
- Delamination
- Wood glue
- Veneer
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