Delamination
The separation of bonded layers in engineered wood products such as plywood, laminated beams, or veneered panels when the adhesive bond fails.
In-Depth Explanation
Delamination is a serious structural and aesthetic defect in any wood product relying on glue bonds between layers. In plywood, delamination appears as bubbling, lifting, or separation between veneer plies, often starting at edges exposed to moisture. Glulam beams can delaminate along their lamination lines if subjected to prolonged moisture cycling or improper adhesive application. The type of adhesive used is the primary factor in delamination resistance: exterior-rated phenol-formaldehyde resins withstand moisture far better than interior urea-formaldehyde adhesives. Preventing delamination requires using the correct product grade for exposure conditions and sealing end grain. Delaminated structural members should be evaluated by an engineer.
Usage Example
After years of roof leaks, the plywood subfloor showed severe delamination with the top veneer peeling away from underlying plies.