prEN 205

• Abstract:

  This European Standard specifies tests for adhesives for wood and derived timber products for the assessment of their resistance to hot and cold water. It can be used for the assessment of the strength of bonds with a thin bond-line. It does not apply to adhesives for structural use or to the manufacture of particleboards, fibreboards and plywood. It does not replace tests on finished products.

• Status: Not Published
• Publication Date: 27-Feb-2028
• ICS: 83.180 - Adhesives
• Technical Committee: CEN/TC 193 - Adhesives
• Drafting Committee: CEN/TC 193/SC 1/WG 12 - Adhesives for non-loadbearing timber structures
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 13-Aug-2026
• Due Date: 11-Nov-2026
• Completion Date: 13-Aug-2026
• Ref Project: oSIST prEN 205:2026 - Adhesives - Wood adhesives for non-structural applications - Determination of tensile shear strength of lap joints

• Revises: EN 205:2016 - Adhesives - Wood adhesives for non-structural applications - Determination of tensile shear strength of lap joints
• Effective Date: 19-Jan-2023

prEN 205 is a draft European Standard from CEN for testing wood adhesives used in non-structural applications. It specifies how to determine the tensile shear strength of lap joints and how the test is used to assess resistance to hot and cold water. The document is for laboratories, adhesive manufacturers, quality staff, and buyers who need a common method for comparing or classifying wood adhesives.

What does prEN 205 specify?

prEN 205 specifies a test method for adhesives for wood and derived timber products when the main question is how well the bonded joint resists water exposure and shear loading. It is aimed at thin bond-line joints, so it is relevant when the adhesive layer is very small and the joint quality depends on surface preparation, spreading, pressing, and conditioning.

The standard does not cover structural adhesives, and it is not intended for the manufacture of particleboards, fibreboards, or plywood. It also does not replace testing on finished products, so it is a laboratory method for adhesive evaluation rather than a final-product approval method.

The document is organized into:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and definitions
• Clause 4 - Principle
• Clause 5 - Apparatus
• Clause 6 - Procedure
• Clause 7 - Expression of results
• Clause 8 - Test report
• Annex A - Informative single lap joint test pieces
• Annex B - Informative examples of adhesive application equipment and conditioning devices

Annex	What it covers
Annex A	Single lap joint test pieces for in-house tests and quick-setting adhesives
Annex B	Examples of adhesive application equipment and devices for handling specimens during conditioning

What are the key requirements of prEN 205?

prEN 205 requires a controlled lap-joint test on beech adherends, followed by conditioning and tensile loading to rupture. In practice, the value of the method comes from keeping the wood, bonding, conditioning, and loading steps consistent so results can be compared between adhesives and between laboratories.

Clause 4 - test principle

prEN 205 uses a symmetrical single lap joint made from two wooden adherends, which is conditioned and then loaded in tension parallel to the grain until rupture. This means the result reflects both the adhesive and the bonded wood interface under a defined mechanical stress.

Clause 5 - apparatus

prEN 205 requires a constant-rate-of-traverse tensile testing machine in line with ISO 5893, with jaws that self-align and grip by wedge action. For the reader, this means the machine must pull smoothly and centrally so the joint is not distorted by the test setup.

Clause 6.1 to 6.3 - preparation of panels, bonded assemblies and test pieces

prEN 205 specifies beech panels with defined conditioning and moisture control, followed by light surface preparation shortly before bonding. The bonded panels must be assembled as thin bond-line joints, and the test pieces are cut from the bonded assembly after conditioning. In practice, this controls variables that strongly affect adhesive strength, especially wood moisture, surface condition, and overlap geometry.

Clause 6.2 - bonding conditions

prEN 205 requires the user to follow the adhesive manufacturer's instructions for spreading, assembly times, and pressing conditions, and to report them. If no instructions are available, the standard gives default processing conditions. This matters because the test is meant to show adhesive performance under known bonding conditions, not under an unspecified shop process.

Clause 6.4 to 6.6 - test sequence

prEN 205 requires 20 test pieces for each conditioning sequence and then tensile shear testing after the chosen pre-treatment. The traverse rate depends on whether the adhesive is being compared or classified under EN 204, EN 12765, or EN 17619. For the reader, this links the test result directly to the durability classification route being used.

Clause 7 and 8 - results and reporting

prEN 205 calculates tensile shear strength from the maximum force and bonded area, and the report must include adhesive identification, wood data, bonding details, conditioning sequence, traverse rate, and all valid and invalid results. This makes the test traceable, so a lab or buyer can understand exactly how the number was obtained.

What terms does prEN 205 define?

• Thin bond line - A close-contact adhesive joint with a nominal adhesive layer thickness of 0.1 mm.
• Open assembly time - The maximum time allowed between applying adhesive and assembling the joint without losing bond strength.
• Durability class - A classification used with EN 204, EN 12765, or EN 17619 to relate adhesive performance to use conditions.
• Conditioning sequence - The specified environmental treatment applied to bonded test pieces before tensile shear testing.
• Rate of traverse - The crosshead speed of the tensile testing machine during the test.
• Constant-rate-of-traverse machine - A tensile test machine that moves at a controlled, constant speed as specified in ISO 5893.

Who uses prEN 205?

prEN 205 is used by adhesive manufacturers, testing laboratories, and quality control teams that need to measure and compare wood adhesive performance. It is also used by certification bodies, product developers, and technical buyers who need evidence for durability classification, process control, or supplier qualification. The method is most relevant in the wood products sector for non-structural bonded joints.

What changed in prEN 205 from the previous edition?

prEN 205 is prepared to supersede EN 205:2016. The foreword states these changes:

• the scope now explicitly says the method is relevant for thin bond-line strength assessment
• Clause 3 adds the term open assembly time
• Clause 5 updates the testing machine apparatus
• Clause 6.1 adds details linking standard climates with wood moisture content
• Clause 6.2 clarifies adhesive spread
• Clause 6.3 introduces a new title for Figure 2
• Annex B is new and gives examples of adhesive application equipment and specimen-handling devices
• Clause 6.6 adds traverse-rate guidance for each durability class

Which standards are used with prEN 205?

prEN 205 uses these normative references:

• EN 204 - classification of thermoplastic wood adhesives for non-structural applications
• EN 923 - terms and definitions for adhesives
• EN 12765 - classification of thermosetting wood adhesives for non-structural applications
• EN 17619 - classification of wood adhesives for non-structural timber products for exterior use
• ISO 5893 - specification for constant-rate-of-traverse test equipment
• ISO 13061-2 - method used to determine wood density for the panel preparation requirements

The bibliography also points to EN 14257 for elevated-temperature tensile testing, ISO 6344-2 for abrasive grain size, and EN ISO 6076 for trowel notch sizes used in adhesive application equipment.

What does the prEN 205 document contain?

prEN 205 contains a complete laboratory test method, from selecting and preparing beech panels through bonding, conditioning, cutting, and tensile testing. It includes two informative annexes with specimen drawings, application equipment examples, and specimen-handling devices for conditioning sequences.

The document also includes a calculation formula for tensile shear strength and a test report section that defines what must be recorded. In practice, that makes the standard useful for method validation, comparative testing, classification work, and technical reporting.

SLOVENSKI STANDARD
01-oktober-2026
Lepila - Lepila za les za nekonstrukcijsko uporabo - Ugotavljanje natezno-strižne
trdnosti spojev s preklopom
Adhesives - Wood adhesives for non-structural applications - Determination of tensile
shear strength of lap joints
Klebstoffe - Holzklebstoffe für nichttragende Anwendungen - Bestimmung der
Klebfestigkeit von Längsklebungen im Zugversuch
Adhésifs - Colles pour bois à usages non structuraux - Détermination de la résistance au
cisaillement en traction des joints à recouvrement
Ta slovenski standard je istoveten z: prEN 205
ICS:
83.180 Lepila Adhesives
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2026
ICS 83.180 Will supersede EN 205:2016
English Version
Adhesives - Wood adhesives for non-structural
applications - Determination of tensile shear strength of
lap joints
Adhésifs - Colles pour bois à usages non structuraux - Klebstoffe - Holzklebstoffe für nichttragende
Détermination de la résistance au cisaillement en Anwendungen - Bestimmung der Klebfestigkeit von
traction des joints à recouvrement Längsklebungen im Zugversuch
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 193.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 205:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 5
5 Apparatus . 6
6 Procedure . 6
6.1 Preparation of the panels . 6
6.2 Preparation of bonded assemblies . 6
6.3 Preparation of test pieces . 8
6.4 Number of test pieces . 9
6.5 Treatment prior to tensile shear testing . 9
6.6 Tensile shear test . 9
7 Expression of results . 9
8 Test report . 9
Annex A (informative) Single lap joint test pieces . 11
Annex B (informative) Examples of adhesive application equipment and devices to handle
the specimen during conditioning sequences . 12
Bibliography . 16

European foreword
This document (prEN 205:2026) has been prepared by Technical Committee CEN/TC 193 “Adhesives”,
the secretariat of which is held by UNE.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 205:2016.
Compared to EN 205:2016 the following modifications have been made:
a) in the scope it is specified that the standard is relevant to assess the strength of bonds with a thin
bond line;
b) in Clause 3 the definition relevant to “open assembly time” was added;
c) in Clause 5, updating of testing machine apparatus;
d) in Clause 6.1 specific details to correlate standard climates and wood moisture contents was
introduced;
e) in Clause 6.2 a clearer explanation about adhesive spread was introduced;
f) in Clause 6.3 a new title for Figure 2 was introduced;
g) New Annex B “Examples of adhesive application equipment and devices to handle the specimen
during conditioning sequences” was introduced;
h) in Clause 6.6 rate of traverse for each durability class was introduced.
Introduction
European Standards giving a common classification with respect to durability classes for wood adhesives
will allow considerable improvement in consumer protection in any future product liability system with
regard to properties guaranteed by the adhesive manufacturer.
The methods described in this document are suitable for the following and other applications:
— assessing the usability and quality of adhesives for wood and derived timber products for non-
structural applications;
— classifying these adhesives into the durability classes:
— D1 to D4 of EN 204 (thermoplastic adhesives),
— C1 to C4 of EN 12765 (thermosetting adhesives),
— XT5 to XT7 of EN 17619 (wood adhesives for exterior use);
— assessing effects on the bond strength resulting from the bonding conditions chosen, the various
conditioning sequences and the treatment of the test pieces before and after bonding;
— testing heat resistance of thermoplastic wood adhesives according to EN 14257 (WATT ’91).
SAFETY STATEMENT — Persons using this document should be familiar with the normal
laboratory practice, if applicable. This document does not purport to address all of the safety
problems, if any, associated with its use. It is the responsibility of the user to establish appropriate
safety and health practices and to ensure compliance with any regulatory conditions.
ENVIRONMENTAL STATEMENT — It is understood that some of the material permitted in this
document may have negative environmental impact. As technological advantages lead to
acceptable alternatives for these materials, they will be eliminated from this document to the
extent possible.
At the end of the test, it is essential that the user of the standard take care to carry out an
appropriate disposal of the wastes, according to local regulation.
1 Scope
This document specifies tests for adhesives for wood and derived timber products for the assessment of
their resistance to hot and cold water. It is used for the assessment of the strength of bonds with a thin
bond-line. It does not apply to adhesives for structural use or to the manufacture of particleboards,
fibreboards and plywood. It does not replace tests on finished products.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 204, Classification of thermoplastic wood adhesives for non-structural applications
EN 923, Adhesives — Terms and definitions
EN 12765, Classification of thermosetting wood adhesives for non-structural applications
EN 17619, Classification of wood adhesives for non-structural timber products for exterior use
ISO 5893, Rubber and plastics test equipment — Tensile, flexural and compression types (constant rate of
traverse) — Specification
ISO 13061-2:2014/Amd 1:2017, Physical and mechanical properties of wood — Test methods for small
clear wood specimens — Part 2: Determination of density for physical and mechanical tests
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 923 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
thin bond line
close contact adhesive joint where the adhesive layer is nominally 0,1 mm thick
3.2
open assembly time
maximum interval between adhesive application to the adherends a
...