ISO 20152-2:2011

Overview

ISO 20152-2:2011 - Timber structures - Bond performance of adhesives - Part 2: Additional requirements specifies optional, jurisdiction-dependent performance requirements for wood bond lines used in prefabricated structural timber components. Prepared by ISO/TC 165, this part supplements ISO 20152-1 (Basic requirements) and addresses higher-risk conditions such as high‑temperature creep, high‑temperature shear rupture, and gap‑filling performance of adhesives for timber structures.

Key topics and technical requirements

• Scope and application

  • Applies to bond‑line performance in prefabricated structural timber products (e.g., glulam, LVL) when additional qualification is required by product standards or local regulation.
  • Requirements are optional and intended for situations needing elevated temperature or gap‑filling evaluation.

• High‑temperature creep resistance

  • Tests at 180 °C or higher (see test method references).
  • Performance limits: average creep displacement for all bonded cross‑sections per specimen shall not exceed 0.6 mm; maximum average creep at any single bonded cross‑section shall not exceed 2.9 mm after the prescribed load period.
  • Load condition: maintained stress level of (2.1 ± 0.1) MPa for 2 h (adjusted for spring constant at temperature).

• High‑temperature shear strength

  • Tests at 220 °C or higher, following the general principle of ASTM D7247.
  • Bonded specimen performance is compared to matched solid wood control specimens; exposure durations or shear retention criteria are set in consultation with product standards, manufacturers, or evaluation agencies.

• Gap‑filling capability

  • Evaluated for bond lines thicker than 1.0 mm (tests typically up to 2.0 mm).
  • Performance criteria are subject to agreement between adhesive manufacturer and user; basic performance must conform to ISO 20152-1.

• Specimen preparation & materials

  • Hardwood reference: hard maple (Acer saccharum / A. nigrum).
  • Softwood references: lodgepole pine, black spruce, Douglas fir, or alternatives as specified.
  • Oven‑dry specific gravity thresholds: ≥ 0.65 (hardwoods); ≥ 0.49 (softwoods).
  • Conditioning and moisture control per ISO 3130 and adhesive manufacturer’s recommendations.

Practical applications and users

• Who uses ISO 20152-2:

  • Adhesive manufacturers qualifying adhesives for structural timber.
  • Timber product manufacturers (glulam, LVL, laminated veneer timber) validating production changes or new adhesives.
  • Independent test laboratories, certification bodies, and code evaluation agencies establishing compliance evidence.
  • Regulatory authorities and design engineers assessing fire‑exposed or high‑temperature performance of bonded timber assemblies.

• Practical benefits:

  • Provides standardized tests and acceptance criteria for demanding service conditions (fire protection, thick bond lines, high‑temperature exposure).
  • Supports product qualification, code compliance, and consistent lab testing practices.

Related standards

• ISO 20152-1: Basic requirements (companion document)
• ISO 3130: Moisture content determination
• ISO 12579: Shear strength test methods for glue lines
• ASTM D7247: Elevated temperature shear strength testing principles

Keywords: ISO 20152-2, timber structures, bond performance, adhesives, high temperature creep, shear strength, gap filling, glulam, LVL, adhesive qualification.