EN 16254:2023 PDF

Overview

EN 16254:2023 - issued by CEN - specifies classification and performance requirements for emulsion polymer isocyanate (EPI) adhesives intended for the industrial manufacture of load-bearing timber structures. The standard defines how EPI adhesives are assessed for suitability in defined climatic exposure conditions (service classes) and sets mandatory test-based performance criteria. It applies to the adhesive product only - not the finished timber element - and is intended mainly for adhesive manufacturers and timber product producers.

Key topics and technical requirements

• Scope & limitations
  • Applies to EPI adhesives (water-based emulsion polymers cross-linked with isocyanate).
  • For industrial (factory) bonding of load-bearing timber products only; excludes on-site gluing (except factory-like conditions), most wood-based panels (except solid wood panels) and highly modified/stabilized woods (e.g., acetylated, heat-treated, polymer-impregnated).
• Classification
  • Adhesives are classified according to suitability in climatic exposure conditions (service class 1 / service class 2), reflecting expected moisture-related performance.
• Performance tests referenced
  • Bond strength in longitudinal tensile shear (EN 302-1)
  • Resistance to delamination (EN 302-2)
  • Tensile strength perpendicular to the bond line after climatic treatment (acid damage test, EN 302-3)
  • Effect of wood shrinkage on shear strength (EN 302-4)
  • Static load tests and creep deformation tests under cyclic climate (EN 302-8, EN 15416-3)
  • Long-term sustained load “Glass house test” (EN 15416-1)
  • Delamination test on finger-jointed pieces (Annex A / EN 301)
  • Working properties: working life, open assembly time, pressing time (EN 302-7, EN 15416-4/5)
• Marking & labelling
  • The standard requires clear identification of adhesive type and performance to support quality control and traceability.

Practical applications

• Ensures EPI adhesives used in manufacturing of: glulam, glued solid timber members, finger-jointed elements and other bonded load-bearing timber products meet durability and mechanical performance expectations.
• Used to demonstrate that an adhesive is adequate for load-bearing use in a given service class - provided the bonding process follows the relevant product standard (e.g., glulam production standards).
• Supports quality control, product development, supplier qualification and regulatory compliance for manufacturers and specifiers.

Who should use this standard

• Adhesive manufacturers developing and certifying EPI adhesives.
• Timber product manufacturers (glulam / engineered timber producers) assessing adhesive suitability.
• Product standards writers, test laboratories, and structural engineers specifying bonded timber in accordance with Eurocode 5 (EN 1995-1-1).

Related standards (selection)

• EN 302 series (test methods for adhesives)
• EN 15416 series (long-term and working property tests)
• EN 14080 (glued laminated timber)
• EN 923 (adhesive terminology)

By aligning with EN 16254:2023, manufacturers and specifiers can ensure EPI adhesives meet harmonized EU requirements for bonded, load-bearing timber under defined climatic exposures.