SIST EN 16254:2023

SLOVENSKI STANDARD
SIST EN 16254:2023
01-april-2023
Lepila - Emulzijsko polimerizirani izocianat (EPI) za nosilne lesene konstrukcije -
Razvrstitev in zahtevane lastnosti
Adhesives - Emulsion polymer isocyanate (EPI) for load-bearing timber structures -
Classification and performance requirements
Klebstoffe - Emulsionspolymerisiertes Isocyanat (EPI) für tragende Holzbauteile -
Klassifizierung und Leistungsanforderungen
Adhésifs - Isocyanate de polymère en émulsion (EPI) pour structures portantes en bois -
Classification et exigences de performance
Ta slovenski standard je istoveten z: EN 16254:2023
ICS:
83.180 Lepila Adhesives
91.080.20 Lesene konstrukcije Timber structures
SIST EN 16254:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 16254:2023

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SIST EN 16254:2023


EN 16254
EUROPEAN STANDARD

NORME EUROPÉENNE

February 2023
EUROPÄISCHE NORM
ICS 83.180 Supersedes EN 16254:2013+A1:2016
English Version

Adhesives - Emulsion polymer isocyanate (EPI) for load-
bearing timber structures - Classification and performance
requirements
Adhésifs - Isocyanate de polymère en émulsion (EPI) Klebstoffe - Emulsionspolymerisiertes Isocyanat (EPI)
pour structures portantes en bois - Classification et für tragende Holzbauteile - Klassifizierung und
exigences de performance Leistungsanforderungen
This European Standard was approved by CEN on 18 December 2022.

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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists 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.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16254:2023 E
worldwide for CEN national Members.

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SIST EN 16254:2023
EN 16254:2023 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Classification . 8
5 Requirements . 10
5.1 General . 10
5.2 Bond strength in longitudinal tensile shear test . 10
5.3 Resistance to delamination . 11
5.4 Tensile strength perpendicular to the bond line after climatic treatment (acid
damage test) . 12
5.5 Effect of wood shrinkage on the shear strength. 12
5.6 Static load test of multiple bond line specimens in compression shear . 12
5.7 Creep deformation test at cyclic climate conditions with specimens loaded in
bending shear . 13
5.8 Long term sustained load test at cyclic climate conditions with specimens loaded
perpendicular to the bond line (“Glass house test”) . 13
5.9 Delamination test on finger-jointed test pieces . 13
6 Test methods . 13
6.1 General . 13
6.2 Determination of bond strength in longitudinal tensile shear test . 13
6.3 Determination of resistance to delamination . 13
6.4 Determination of tensile strength perpendicular to the bond line after climatic
treatment (acid damage test) . 13
6.5 Determination of the effect of wood shrinkage on the shear strength . 13
6.6 Static load test of multiple bond line specimens in compression shear . 14
6.7 Creep deformation test with specimens loaded in bending shear . 14
6.8 Long term sustained load test at cyclic climate conditions with specimens loaded
perpendicular to the bond line (“Glass house test”) . 14
6.9 Delamination test on finger-jointed test pieces . 14
7 Working properties of the adhesive . 14
7.1 General . 14
7.2 Determination of working life under reference conditions . 14
7.3 Determination of open assembly time under reference conditions. 15
7.4 Determination of pressing time under reference conditions . 15
8 Marking and labelling . 15
Annex A (normative) Delamination test for bonding of finger-joints . 16
A.1 Production of the specimens . 16
A.2 Testing . 17
A.3 Expression of results . 17
A.4 Test report . 18
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SIST EN 16254:2023
EN 16254:2023 (E)
A.4.1 Adhesive . 18
A.4.2 Preparation of test pieces and testing procedure . 18
A.4.3 Test results . 18
Annex B (informative) Product limitations and glulam production control for beams
produced with Small dimension adhesives . 19
B.1 Product limitations . 19
B.2 Control of the glue line thickness . 19
Bibliography . 20

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SIST EN 16254:2023
EN 16254:2023 (E)
European foreword
This document (EN 16254:2023) has been prepared by Technical Committee CEN/TC 193 “Adhesives”,
the secretariat of which is held by UNE.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2023, and conflicting national standards shall be
withdrawn at the latest by August 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 16254:2013+A1:2016.
EN 16254:2023 includes the following significant technical changes with respect to
EN 16254:2013+A1:2016:
a) the title has been changed;
b) the designation of adhesive types has been modified and aligned with EN 301 and EN 15425;
c) the reference to EN 15416-2 has been replaced by reference to EN 302-8;
d) for the delamination test according to EN 302-2 with preservative treated wood, a test with Scots
pine (Pinus sylvestris) and Silver fir (Abieas alba) covers also Norway spruce (Picea abies L.);
e) for adhesive type FJ, the test according to EN 302-2 is required only with short closed assembly time,
and the test according to EN 15416-5 is only required with thin glue line;
f) Annex A on storage treatments for tests according to EN 302-1 has been deleted and replaced by
reference to EN 302-1, the storage time for the temperature treatment (A6, A7, A8) has therefore
been reduced from 72 h to 24 h;
g) for bonding of finger-joints in additional wood species, the test according to EN 302-2 may be
replaced by the delamination test on finger-joints from EN 301, which is specified as new Annex A.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: 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 the United
Kingdom.
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SIST EN 16254:2023
EN 16254:2023 (E)
Introduction
This document is one of a series dealing with emulsion polymer isocyanate (EPI) adhesives for use with
timber structures, and is published in support of product standards for bonded load-bearing timber
structures in connection with EN 1995-1-1, Eurocode 5: Design of timber structures — Part 1-1:
General — Common rules and rules for buildings.
The series consists of:
— one standard for classification and performance requirements (EN 16254);
— eight test methods (EN 302-1, EN 302-2, EN 302-3, EN 302-4, EN 302-8, EN 15416-1, EN 15416-3
and the test method given in Annex A of this document (“finger-joint delamination test”) used to
assess the performance of adhesives after specified heat and humidity treatments; and
— three test methods (EN 302-7, EN 15416-4 and EN 15416-5) to characterize the working properties
of the adhesive.
Safety statement
Persons using this document should be familiar with the normal laboratory practice, if applicable. This
document cannot 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 better alternatives for these materials, they will be eliminated
from this European Standard to the extent possible.
At the end of the test, it is recommended that the users of this document take care to carry out an
appropriate disposal of the wastes, according to local regulations.
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SIST EN 16254:2023
EN 16254:2023 (E)
1 Scope
This document establishes a classification for emulsion polymer isocyanate (EPI) adhesives according to
their suitability for use in load-bearing timber products in defined climatic exposure conditions, and
specifies performance requirements for such adhesives for the industrial manufacture of load-bearing
timber products only.
The performance requirements of this document are applicable to the adhesives only, not to the timber
products. This document does not cover the performance of adhesives for on-site gluing (except for
factory-like conditions) or the production of wood-based panels, except solid wood panels, or modified
and stabilized wood with considerably reduced swelling and shrinkage properties, e.g. acetylated wood,
heat treated wood and polymer impregnated wood.
This document is primarily intended for use by adhesive manufacturers and for use in timber products
bonded with adhesives, to assess or control the quality of adhesives. This document only specifies the
performance of an adhesive for use in an environment corresponding to the defined conditions.
Such an adhesive meeting the requirements of this document for its type is adequate for use in load-
bearing timber products, provided that the bonding process has been carried out according to an
appropriate product standard.
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 302-1, Adhesives for load-bearing timber structures — Test methods — Part 1: Determination of
longitudinal tensile shear strength
EN 302-2, Adhesives for load-bearing timber structures — Test methods — Part 2: Determination of
resistance to delamination
EN 302-3, Adhesives for load-bearing timber structures — Test methods — Part 3: Determination of the
effect of acid damage to wood fibres by temperature and humidity cycling on the transverse tensile strength
EN 302-4, Adhesives for load-bearing timber structures — Test methods — Part 4: Determination of the
effects of wood shrinkage on the shear strength
EN 302-7, Adhesives for load-bearing timber structures — Test methods — Part 7: Determination of the
working life under referenced conditions
EN 302-8, Adhesives for load-bearing timber structures — Test methods — Part 8: Static load test of
multiple bond line specimens in compression shear
EN 923, Adhesives — Terms and definitions
EN 13183-2, Moisture content of a piece of sawn timber — Part 2: Estimation by electrical resistance
method
EN 13183-3, Moisture content of a piece of sawn timber — Part 3: Estimation by capacitance method
EN 14080, Timber structures — Glued laminated timber and glued solid timber — Requirements
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SIST EN 16254:2023
EN 16254:2023 (E)
EN 15416-1, Adhesives for load bearing timber structures other than phenolic and aminoplastic — Test
methods — Part 1: Long-term tension load test perpendicular to the bond line at varying climate conditions
with specimens perpendicular to the glue line (Glass house test)
EN 15416-3, Adhesives for load bearing timber structures other than phenolic and aminoplastic — Test
methods — Part 3: Creep deformation test at cyclic climate conditions with specimens loaded in bending
shear
EN 15416-4, Adhesives for load bearing timber structures other than phenolic and aminoplastic — Test
methods — Part 4: Determination of open assembly time under referenced conditions
EN 15416-5, Adhesives for load bearing timber structures other than phenolic and aminoplastic — Test
methods — Part 5: Determination of minimum pressing time under referenced conditions
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
emulsion polymer isocyanate (EPI) adhesive
water based emulsion polymer or a mixture of water based emulsion polymers cross-linked with an
isocyanate as hardener
3.2
service class 1
climatic conditions characterised by a moisture content in the materials corresponding to a temperature
of 20 °C and the relative humidity of the surrounding air only exceeding 65 % for a few weeks per year
Note 1 to entry: In service class 1, which comprises typical indoor conditions, the average moisture content in
most soft-woods will not exceed 12 %.
[SOURCE: EN 1995-1-1:2004, 2.3.1.3 modified – Indoor conditions have been added in Note 1 to entry.]
3.3
service class 2
climatic conditions characterized by a moisture content in the materials corresponding to a temperature
of 20 °C and the relative humidity of the surrounding air only exceeding 85 % for a few weeks per year
Note 1 to entry: In service class 2, to which most covered exterior conditions belong, the average moisture
content in most softwoods will not exceed 20 %.
[SOURCE: EN 1995-1-1:2004, 2.3.1.3, modified – Covered exterior conditions have been added in Note 1
to entry.]
3.4
service class 3
climatic conditions leading to higher moisture contents than in service class 2
Note 1 to entry: Exterior conditions typically belong to service class 3.
[SOURCE: EN 1995-1-1:2004, 2.3.1.3, modified – Note 1 to entry has been added.]
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SIST EN 16254:2023
EN 16254:2023 (E)
3.5
glue line
adhesive layer between the wood members
3.6
close contact glue line
glue line of thickness maximum 0,1 mm
Note 1 to entry: Close contact glue line can be achieved by pressing together two plane wood members with a
2
clamping pressure of (0,8 ± 0,1) N/mm without additional groves, spacers or similar devices.
3.7
thick glue line
glue line of nominal thickness in the range of 0,2 mm to 0,5 mm at the time of bonding
Note 1 to entry: Thick glue lines are achieved by using spacers, grooves or similar devices when two plain
members are glued together.
4 Classification
Adhesives for structural purpose shall produce joints of such strength and durability that the integrity of
the bond is maintained in the assigned service class throughout the expected life of the structure.
EPI-adhesives according to EN 16254 are classified by type (climate condition in use), maximum test
temperature and maximum glue line thickness in use. These three classification criteria are subdivided
as follows:
Type I: to be used in service class 1 and 2.
Type II: to be used in service class 1 only.
Maximum test temperature: 50 °C, 70 °C or 90 °C.
Maximum glue line thickness in use: 0,1 mm, 0,2 mm and 0,3 mm.
Depending on the maximum glue line thickness in use, the adhesives are assigned to different application
areas as described below and shown in Table 1.
— General purpose adhesives (GP): to be used for bond lines between laminations (maximum glue
line thickness 0,3 mm) and for finger-joints in laminations and structural timber.
2
— Small dimension adhesives (SD): to be used in beams with a maximum cross section 45 000 mm
(maximum glue line thickness 0,2 mm) and for finger-joints in laminations and structural timber. The
beam width shall not exceed 180 mm and the beam height shall not exceed 300 mm.
— Finger-jointing adhesives (FJ): to be used for finger-jointing of laminations and structural timber
only (maximum glue line thickness 0,1 mm).
The application of EPI shall always be in mixed state. These adhesives shall be applied according to the
manufacturer's instructions.
NOTE The definition of “General purpose” and “Type” can be different in other standards.
Each area of application and use shall be given in the designation code of the adhesive.
Adhesives tested for working properties according to Clause 7 are specified by the letter “w” at the end
of the designation code (example: EN 16254 I 90 GP 0,3 w).
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EN 16254:2023 (E)
Table 1 — Adhesive classes
Adhesive class Application area Max. test Max. glue line Service classes
a
(designation code) temperature thickness
  Test Use
 °C mm mm
Normal use
EN 16254 I 70 GP 0,3 General purpose 70 0,5 0,3 1, 2
 Special use
EN 16254 I 90 GP 0,3 General purpose 90 0,5 0,3 1, 2
EN 16254 I 90 SD 0,2 Small dimension 90 0,3 0,2 1, 2
EN 16254 I 90 FJ 0,1 Finger-jointing 90 0,3 0,1 1, 2
EN 16254 I 70 SD 0,2 Small dimension 70 0,3 0,2 1, 2
EN 16254 I 70 FJ 0,1 Finger-jointing 70 0,3 0,1 1, 2
EN 16254 II 50 GP 0,3 General purpose 50 0,5 0,3 1
EN 16254 II 50 SD 0,2 Small dimension 50 0,3 0,2 1
EN 16254 II 50 JF 0,1 Finger-jointing 50 0,3 0,1 1
a
Tested according to EN 302-8 and EN 302-1, designation A6, A7 and A8.
A classification to a certain “maximum test temperature” will automatically be valid for lower
temperatures.
Table 2 specifies the tests that shall be performed for each application area. References are given to the
actual subclause in this document and to the European Standard the tests are based on.
Table 2 — Necessary tests for adhesive use in difference application areas
Application Glue line EN 302-1 EN 302-2 EN 302-3 EN 302-4 EN 302-8 EN 15416-3 EN 15416-1
area thickness (based (based on (based on (based on (based on (based on (based on
a b
in test on 6.2) 6.3) 6.4) 6.5) 6.6) 6.7) 6.8)
mm
d
0,1 X X   X  X
General
0,3      X
purpose
0,5 X  X X   X
d
0,1 X X   X  X
Small
0,2      X
dimension
0,3 X  X X   X
d c
0,1 X X X  X X X
Finger-
jointing
0,3 X
a
Climate treatment A1 to A5 and A6 or A7 or A8, depending on maximum test temperature (see Table 1 and
EN 302-1).
b
Maximum test temperature according to Table 1.
c
Only with short closed assembly time.
d
As defined in 3.6, close contact.
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SIST EN 16254:2023
EN 16254:2023 (E)
5 Requirements
5.1 General
Adhesives complying with this document shall meet the performance requirements specified in 5.2 to 5.9
when tested in accordance with the following test methods:
a) The tensile shear test (see 5.2 and 6.2) using bonded test pieces made from beech (Fagus sylvatica L.).
b) The delamination test (see 5.3 and 6.3) on bonded test pieces made from Norway spruce (Picea
abies L.). If the adhesive is to be used on wood from other coniferous species like larch (Larix
decidua), douglas fir (Pseudotsuga menziesii) and pines with coloured heartwood other than Scots
pine (Pinus sylvestris), from hardwood species and/or preservative treated wood, also prepare four
laminated members using representative samples from those species or wood treated that way.
The test with representative samples of preservative treated Scots pine (Pinus sylvestris) or
preservative treated silver fir (Abies alba) also covers preservative treated Norway spruce (Picea
abies L.).
When testing an adhesive within application area Finger-jointing for the bonding of wood species
other than Norway spruce (Picea abies L.), silver fir (Abieas alba) and Scots pine (Pinus sylvestris), the
additional delamination test according to EN 302-2 may be replaced by the delamination test
specified in Annex A (delamination test for finger-joints in laminations, see 5.9 and 6.9).
c) Tensile strength perpendicular to the bond line after climatic treatment (see 5.4 and 6.4) on bonded
test pieces made from Norway spruce (Picea abies L.). The test will only be mandatory if the pH value
in the mixed adhesive is lower than 3,0.
d) The shrinkage stress test (see 5.5 and 6.5) on bonded test pieces made from Norway spruce (Picea
abies L.).
e) Static load test (see 5.6 and 6.6) on bonded test pieces made from beech (Fagus sylvatica L.).
f) Creep deformation test under bending shear (see 5.7 and 6.7) on test pieces made from Norway
spruce (Picea abies L.).
g) Long term sustained load test (see 5.8 and 6.8) under cyclic climate conditions perpendicular to the
bond line on test pieces made from beech (Fagus sylvatica L.).
All these tests are to be carried out with ready for use glue mixes, i.e. adhesive and hardener mixed
immediately before application. These adhesives shall be applied according to the manufacturer's
instructions.
NOTE For application area “Small dimension”, requirements regarding product limitations and internal factory
production control within glulam production are given in the informative Annex B of this document. The adhesives
in questions are EN 16254 I 70 SD 02, EN 16254 I 90 SD 02 and EN 16254 I I 50 SD 02.
5.2 Bond strength in longitudinal tensile shear test
When tested in accordance with 6.2, the tensile shear strength values of close contact glue lines, 0,3 mm
and 0,5 mm thick glue lines shall meet the requirements given in Table 3.
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EN 16254:2023 (E)
2
Table 3 — Minimum mean tensile shear strength (N/mm ) for close contact, 0,3 mm and 0,5 mm
thick glue lines after treatments according to EN 302-1
Treatment Close contact 0,3 mm 0,5 mm
(see EN 302-1) Type I Type II Type I Type II Type I Type II
A1 10,0 10,0 9,5 9,5 9,0 9,0
A2 6,0 6,0 5,5 5,5 5,0 5,0
A3 8,0 8,0 7,6 7,6 7,2 7,2
a a a
A4 6,0 — 5,5 — 5,0 —
a a a
A5 8,0 — 7,6 — 7,2 —
a a a
A6 — 9,5 — 8,3 — 7,2
a a a
A7 8,0 — 7,2 — 6,5 —
a a a
A8 8,0 — 7,2 — 6,5 —
a
Treatment not required.
NOTE 1 In Table 3 Type I adhesives include:
EN 16254 I 90 GP 0,3
EN 16254 I 90 SD 0,2
EN 16254 I 90 FJ 0,1
EN 16254 I 70 GP 0,3
EN 16254 I 70SD 0,2
EN 16254 I 70 FJ 0,1
NOTE 2 In Table 3 Type II adhesives include:
EN 16254 II 50 GP 0,3
EN 16254 II 50 SD 0,2
EN 16254 II 50 FJ 0,1
5.3 Resistance to delamination
When tested in accordance with 6.3, the limits on delamination shall be those specified in Table 4.
Table 4 — Resistance to delamination after treatment according to EN 302–2

Treatment Maximum delamination of any test piece
% of total glue line length

Type I Type II
Low temperature Not required 10,0
High temperature 5,0 Not required
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SIST EN 16254:2023
EN 16254:2023 (E)
NOTE 1 In Table 4 Type I adhesives include:
EN 16254 I 90 GP 0,3
EN 16254 I 90 SD 0,2
EN 16254 I 90 FJ 0,1
EN 16254 I 70 GP 0,3
EN 16254 I 70 SD 0,2
EN 16254 I 70 FJ 0,1
NOTE 2 In Table 4 Type II adhesives include:
EN 16254 II 50 GP 0,3
EN 16254 II 50 SD 0,2
EN 16254 II 50 FJ 0,1
1)
In the case of specific hardwood species , the following provisions apply:
— The test may be performed with the lamination and glulam cross-section and sawing patterns of the
laminations conforming to the maximum sizes and the laminations sawing patterns used in the
respective product.
— The maximum delamination of any test piece shall be less than or equal to 8 % for adhesive type I
and less than or equal to 12 %
...