prEN 204

• Abstract:

  This European Standard classifies thermoplastic resin based wood adhesives for non-structural applications into durability; classes D1 to D4 based on the dry and wet strengths of bond-lines measured under specified conditions after various; conditioning treatments.; For special applications, further tests that do not fall within the scope of this European standard can be applicable.; The adhesives specified in this European standard are suitable for the bonding of furniture and interior structures,; panelling, doors, windows, stairs etc. made of wood or derived timber products.; This European Standard does not specify the temperature resistance of bond-lines

• 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 204:2026 - Classification of thermoplastic wood adhesives for non-structural applications

• Revises: EN 204:2016 - Classification of thermoplastic wood adhesives for non-structural applications
• Effective Date: 28-Sep-2022

prEN 204 is a CEN draft European Standard for classifying thermoplastic wood adhesives for non-structural applications. It assigns adhesives to durability classes D1 to D4 based on the dry and wet strength of bond-lines after specified conditioning, so manufacturers, test laboratories, specifiers and buyers can judge whether a product fits the intended indoor or protected exterior use.

The standard applies to thermoplastic resin-based wood adhesives used for furniture, interior structures, panelling, doors, windows and stairs made of wood or derived timber products. It focuses on performance classification, not on every special-use test and not on temperature resistance of bond-lines.

What does prEN 204 specify?

prEN 204 specifies a durability classification system for thermoplastic wood adhesives used in non-structural applications. It organizes the work into clauses on scope, normative references, terms and definitions, classification, test method and requirements.

The classification is based on performance after conditioning, using the dry and wet strengths of bond-lines measured under defined conditions. The practical purpose is to let users match an adhesive to the moisture exposure expected in service.

The document also gives examples of the service conditions associated with each durability class:

• D1 for interior use with limited moisture exposure
• D2 for interior use with occasional short-term water exposure or higher humidity
• D3 for more frequent or longer exposure to running or condensed water, including interior use with heavy humidity and exterior use not exposed to weather
• D4 for exterior use exposed to weather but protected by an adequate surface coating

What are the key requirements of prEN 204?

prEN 204 classifies an adhesive by testing thin bond-lines according to prEN 205:2026. In practice, this means the adhesive is not judged by general product claims alone - it must pass the specified shear tests after the relevant conditioning sequence.

Classification basis

prEN 204 uses Table 1 to link each durability class to the expected service environment. The class number is not a ranking, and one adhesive can fit more than one class. That matters when a product is used in several applications or when a buyer wants a conservative declaration.

Test method and conditioning

prEN 204 requires testing in accordance with prEN 205:2026 and with the conditioning sequence assigned to the claimed class. The document allows two standard climates for conditioning, and the specimen must move from one conditioning step to the next immediately. For the wet conditioning sequences, the specimens are submerged, and for sequences 3 and 5 the test is carried out in wet state after removal from water.

Test reporting

prEN 204 requires recording each strength result and the mean value for the set of 20 test pieces for each conditioning sequence. Results affected by wood failure below the specified minimum are invalid, and specimens with visible shape irregularities can still be valid if they meet the requirements. All valid and invalid results, together with the reason for invalidity, must be reported. That is important for traceability in type testing, quality control and dispute resolution.

Pass criteria

prEN 204 sets class-dependent minimum mean strengths in Table 2. The class decision depends on which conditioning sequences apply to the claimed class:

• D1 uses the baseline conditioning sequence
• D2 adds a further wet conditioning sequence
• D3 adds its own wet sequence and a higher wet-strength condition
• D4 adds the most severe wet conditioning sequence, including boiling water exposure

For the user, this means the claimed durability class has to be supported by the whole set of required sequences, not only by one favorable result.

Practical limits

prEN 204 notes that special applications may need additional tests outside its scope. It also states that temperature resistance of bond-lines is not specified, so users who need heat performance must check that separately.

What terms does prEN 204 define?

Thermoplastic resin is a polymer or copolymer that softens when heated and hardens when cooled.

Thermoplastic wood adhesive is an adhesive whose main constituent is a thermoplastic resin and that is formulated for bonding wood.

Durability class is the D1, D2, D3 or D4 category assigned from the test results and intended service conditions.

Bond-lines are the bonded joints whose dry and wet strength are measured in the classification tests.

Standard climate is one of the controlled temperature and relative-humidity conditions used during conditioning before testing.

Who uses prEN 204?

prEN 204 is used by adhesive manufacturers, test laboratories, product developers, quality managers and buyers of wood adhesives. It is also relevant to furniture makers, joinery and timber-product manufacturers working with interior structures, panelling, doors, windows and stairs. In practice, these users apply it when selecting an adhesive, setting incoming-material requirements, or documenting product performance for non-structural wood bonding.

What changed in prEN 204 from the previous edition?

prEN 204 supersedes EN 204:2016. The foreword states that the revision includes edited wording in Clause 5 items a) and b), removal of the phrase “atmosphere used as a control” from the last sentence of Clause 5, an editorial update to Table 2 with a new note d, and a revised water temperature range in Table 2.

Which standards are used with prEN 204?

prEN 204 refers to prEN 205:2026, which provides the tensile shear test method for lap joints and is the basis for the conditioning and strength measurements. It also refers to EN 923, which supplies general adhesive terms and definitions.

The introduction and bibliography also point to EN 12765 for thermosetting wood adhesives in non-structural applications and EN 17619 for wood adhesives for non-structural timber products for exterior use. These help users place prEN 204 alongside related classification systems for other adhesive types.

What does the prEN 204 document contain?

prEN 204 contains a short technical structure: scope, normative references, terms and definitions, classification rules, a test method and performance requirements. Clause 4 includes the service-condition table for D1 to D4, and Clause 5 gives the conditioning sequence approach and reporting rules for the tensile shear test.

Clause 6 provides the minimum mean strength requirements by class and conditioning sequence. The introductory material explains how this D class fits beside the C class and XT class systems used for other wood-adhesive families, which helps users choose the right classification document for the adhesive chemistry and service environment.

SLOVENSKI STANDARD
01-oktober-2026
Razvrstitev plastomernih lepil za les za nekonstrukcijsko uporabo
Classification of thermoplastic wood adhesives for non-structural applications
Klassifizierung von thermoplastischen Holzklebstoffen für nichttragende Anwendungen
Classification des colles thermoplastiques pour bois à usages non structuraux
Ta slovenski standard je istoveten z: prEN 204
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 204:2016
English Version
Classification of thermoplastic wood adhesives for non-
structural applications
Classification des colles thermoplastiques pour bois à Klassifizierung von thermoplastischen Holzklebstoffen
usages non structuraux für nichttragende Anwendungen
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 204:2026 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 Classification. 5
5 Test method . 6
6 Requirements . 6
Bibliography . 8

European foreword
This document (prEN 204:2026) 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 204:2016.
Compared to EN 204:2016 the following modifications have been made:
a) In Clause 5, a) and b) the sentences have been modified;
b) In Clause 5, the last sentence has been modified deleting “atmosphere used as a control”;
c) Table 2 modified editorially and adding note d;
d) Table 2: modified water temperature range.
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.
Wood adhesives for non-structural applications can be classified according to D class, C class and XT class.
D class is relevant for thermoplastic adhesives, such as PVAc, whereas C class (EN 12765) is relevant for
thermosetting adhesives, such as UF and MUF.
Adhesives that can be considered as thermoplastic or thermosetting, such as PU and EPI, according to
manufacturer instructions, can be classified according to D, C or both classes.
XT class (EN 17619) is relevant for all wood adhesives for exterior use.
This document is giving classification with respect to durability classes for thermoplastic wood
adhesives.
1 Scope
This document classifies ther
...