ISO 13785-1:2002

INTERNATIONAL ISO
STANDARD 13785-1
First edition
2002-12-15
Reaction-to-fire tests for façades —
Part 1:
Intermediate-scale test
Essais de réaction au feu des façades —
Partie 1: Essai à échelle intermédiaire

Reference number
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ii ISO 2002 – All rights reserved

Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 3
5 Test facility . 3
6 Fire source and exposure . 3
7 Test specimen . 5
8 Test specimen instrumentation . 5
9 Test specimen conditioning . 7
10 Test environment . 7
11 Procedure . 7
12 Expression of results . 8
13 Precision . 8
14 Test report . 8
Bibliography. 10
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ISO 2002 – All rights reserved iii

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 13785 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 13785-1 was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee
SC 1, Fire initiation and growth.
ISO 13785 consists of the following parts, under the general title Reaction-to-fire tests for façades:
— Part 1: Intermediate-scale test
— Part 2: Large-scale test
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iv ISO 2002 – All rights reserved

Introduction
Fire is a complex phenomenon. Its behaviour and effects depend on a number of interrelated factors. The behaviour
of materials and products depends on the characteristics of the fire, the method of use of the materials and the
[2]
environment in which they are exposed. The theory of “reaction to fire tests” is explained in ISO/TR 3814 .
The need for improved thermal insulation of buildings both for single and multi-storey dwellings and for industrial
buildings has led to an increased use of insulated and often ventilated façades.
With these types of construction products, there are three primary fire threats to the walls and ceilings/roofs of a
building:
a) an interior compartment fire venting through a window on to a façade;
b) an exterior fire in combustibles accumulated near a wall (e.g. rubbish, vegetation);
c) fire in an adjacent building.
Item a) is generally the most severe and substantially the most significant.
Fire can spread in several ways. The most significant is by spread over a combustible exterior surface or the fire
travelling vertically and horizontally through air cavities between claddings or façades, or through the core of
insulation itself.
The results may not, however, reflect the actual performance of exterior wall assemblies under all fire exposure
conditions.
The test specified in this part of ISO 13785 covers a simple representation of one fire scenario with façade products,
typified by a fire within a building venting through a window and impinging directly on to a façade.
The two parts of ISO 13785 provide two methods of test: an intermediate scale test specified in this part, which
should only be used for screening or evaluation of sub-components or “families of products”, and a large scale test
specified in Part 2, which should be used to provide the end-use evaluation of all aspects of the façade system.
These test methods are intended to evaluate assemblies that are not intended for use as an internal lining.
The test specified in this part of ISO 13785 may be used for comparative purposes or to ensure the existence of a
certain quality of performance considered to have a bearing on the fire performance of the façades generally. No
other meaning is attached to performance in this test. The large-scale test in Part 2 of ISO 13785 should be used to
give a more realistic end-use assessment of performance.
The test specified in this part of ISO 13785 does not rely on the use of asbestos-based materials.
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ISO 2002 – All rights reserved v

INTERNATIONAL STANDARD ISO 13785-1:2002(E)
Reaction-to-fire tests for façades —
Part 1:
Intermediate-scale test
WARNING — So that suitable precautions may be taken to safeguard health, all persons involved in the fire
tests should be aware of the possibility that toxic or harmful gases may be evolved during exposure of test
specimens.
Hazards are encountered when assessing the fire performance of any product on an intermediate-scale and
it is essential that adequate precautions be taken.
Particular attention should be paid to the potential evolution of smoke and toxic gases and to the fact that
extensive flaming of specimens can occur sometimes with resultant mechanical failure of fixings and joints
and possible structural collapse.
An adequate means of extinguishing the specimen should be provided.
1 Scope
This part of ISO 13785 specifies a screening method for determining the reaction to fire performance of products and
constructions of façades or claddings when exposed to heat from a simulated external fire with flames impinging
directly upon a façade. It is intended for use by producers to reduce the burden of testing in Part 2 of ISO 13785 by
eliminating those systems that fail the tests described in this part of ISO 13785.
This test method is applicable only to façades and claddings that are not free standing and that are used as an
addition to an existing external wall.
This test method also is only applicable to vertical elements and is not applicable to determining the structural
strength of the façade or cladding.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 13785. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 13785 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated references,
the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of
currently valid International Standards.
ISO 13943:2000, Fire safety — Vocabulary
IEC 60584-2, Thermocouples — Part 2: Tolerances
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ISO 2002 – All rights reserved 1

3 Terms and definitions
For the purposes of this part of ISO 13785, the terms and definitions given in ISO 13943:2000 and the following
apply.
3.1
assembly
fabrication of materials and/or composites
EXAMPLE Sandwich panel.
NOTE An assembly may include an air gap.
3.2
composite
combination of materials that are generally recognized in building construction as discrete entities
EXAMPLE Coated or laminated product.
3.3
constant mass
state of a test specimen when two successive weighing apparatus operations carried out at an interval of 24 h do not
differ by more than 0,1 % of the mass of the specimen or 0,1 g, whichever is greater
3.4
exposed surface
surface of a product subjected to the heating conditions of the test
3.5
façade
cladding
products and constructions added to the external surface of an existing wall or frame
NOTE The structure can be of concrete, lightweight concrete blockwork, masonry, timber, etc. The cladding may be applied
directly to the inner structure or may incorporate an air gap or an insulating layer.
3.6
material
single substance or uniformly dispersed mixture
EXAMPLE Substance made of metal, stone, timber, concrete, mineral fibre or polymers.
3.7
product
material, composite or assembly about which information is required
3.8
specimen
façade or cladding representing the material of the end-use façade, including joints and fixings
NOTE 1 The specimen does not include the lightweight concrete block wall of the test rig.
NOTE 2 The specimen may include an air gap.
3.9
surface product
any part of a building that constitutes an exposed surface on the walls and/or the ceiling/roof
EXAMPLE Panel or board.
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2 ISO 2002 – All rights reserved

4 Principle
The reaction to fire of a façade or cladding is assessed when exposed to flames impinging directly on the face of the
◦
façade or cladding in the intermediate scale. The specimen is constructed with a re-entrant angle of 90 , with the
smaller wall parallel to the draught screens. This type of construction is common in practice and creates a worst-case
situation.
The flame spread and mechanical behaviour of the specimen are assessed by indirect instrumental methods within
the internal cavity of the façade, or directly by observation of the front face of the façade.
5 Test facility
5.1 General
The test apparatus shall consist of a specimen support frame and an ignition source. A schematic representation of
the test apparatus is shown in Figure 1.
5.2 Specimen support frame
The specimen support frame (see Figure 1) shall consist of three walls, i.e. a three-part back wall and two side walls.
The side walls shall be positioned perpendicularly on both sides of the back wall and a small 0,6 m wide
perpendicular side wall. The test specimen shall be attached to a sample holder that is the middle part of the back
wall. The height of all parts of the walls shall be 2,8 m.
The back wall shall consist of two slabs of stone wool with a thickness of 100 mm and a density of 100 kg/m , and a
corner configuration sample holder with a width of 1,2 m, made of a non-combustible board (thickness 12 mm,
750 kg/m
nominal density ). The side wall of the sample holder shall also be constructed of non-combustible board
with a width of 0,6 m. The sample holder shall be positioned centrally between the mineral wool slabs. The total width
of the back wall shall be 2,4 m.
The test specimen shall be attached to the upper part of the sample holder so that the bottom edge of the test
specimen is 0,4 m above floor level when the sample holder is positioned vertically.
The side walls of the specimen support frame shall be made of a non-combustible board. The width of the side walls
shall be 2,4 m. The side walls shall meet the floor, with no air gaps formed.
The specimen support frame shall be located in an open laboratory environment in which adequate ventilation and
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