ISO 17738-3:2019

INTERNATIONAL ISO
STANDARD 17738-3
First edition
2019-08
Thermal insulation products —
Exterior insulation and finish systems
(EIFS) —
Part 3:
Design requirements
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Materials . 2
5 Design criteria . 2
6 Design requirements . 2
7 Substrate design requirements . 3
8 Water-shedding barrier . 3
9 Water-resistive barrier assembly . 3
10 Thermal barrier . 4
11 Air barrier assembly . 4
12 Vapour barrier . 4
13 Fire protection . 4
14 Impact resistance . 5
15 Hygrothermal performance . 5
16 EIFS terminations and interface gaps . 5
16.1 Terminations . 5
16.2 Expansion joints. 6
Annex A (informative) Design considerations for mechanical fasteners . 7
Annex B (informative) EIFS resiliency . 8
Bibliography .12
Foreword
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electrotechnical standardization.
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use
in the built environment, Subcommittee SC 3, Thermal insulation products.
A list of all parts in the ISO 17738 series can be found on the ISO website.
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iv © ISO 2019 – All rights reserved

Introduction
This document provides specifications for architects, design professionals and builders on the
integration of an exterior insulation and finish system (EIFS) into their projects.
This document is predicated on the selected EIFS assembly being in compliance with the requirements
of ISO 17738-1, and system installation in compliance with ISO 17738-2.
The design criteria in this document are based on the principle that the building envelope contains five
‘planes-of-control’:
— water-shedding barrier;
— water-resistive barrier;
— thermal barrier;
— air barrier;
— vapour barrier.
Each plane-of-control corresponds to an individual function that the cladding assembly is designed to
perform. The function of the planes-of-control are:
— Water-shedding barrier: This is designed to deflect rainwater away from the wall surface, thereby
minimizing water penetration into the cladding assembly.
— Water resistive barrier: Accepting that some water could find its way behind the cladding, a
continuous water resistive barrier is required to protect the substrate. Water that penetrates one
cladding component should not be directed to drain behind another. Any water that reaches the
water resistive barrier should have a clear drainage path to the exterior of the cladding.
— Continuous thermal barrier: The principle benefit of an EIFS cladding is the continuous thermal
barrier installed on the exterior of the structure. Insulation should be adequate to prevent
condensation within the wall assembly while meeting requirements for energy use. The designer
should detail the thermal barrier to minimize thermal bridging, using ISO 14683 as a guide.
— Air barrier system: Effective thermal and moisture control requires a continuous air barrier system
on all faces of the building envelope. With an EIFS, the air barrier function is provided by the water
resistive barrier. Details should show connections with other airtight elements and materials within
the building envelope.
— Vapour barrier: Where required by environmental conditions, a vapour barrier, may be a component
of the EIFS. The vapour barrier might, for example be a vapour-impermeable water resistive barrier
or another material in the wall assembly (e.g. polyethylene sheet). The function of the vapour
barrier is to minimize water vapour penetrating through materials comprising the wall assembly
then condensing on a cold surface where it has limited ability to drain or dry.
This document addresses the minimum number of locations in the wall assembly where the creation
of architectural details is essential. When creating EIFS details for a project, the designer should be
mindful of how the five planes-of-control within the building envelope are integrated across the various
architectural components (e.g. the air barrier of a window functions as a hermetic part of the air barrier
system when structurally sealed to the air barrier of the wall).
An important aspect of developing details is to specify materials that meet the function of each plane-
of-control. The detail then illustrates how the control planes are connected. A series of illustrations
showing sequence of installation and connection could be necessary. Each detail should clearly illustrate
how a plane-of-control is integrated with the adjacent element to provide a continuous layer within the
building envelope.
INTERNATIONAL STANDARD ISO 17738-3:2019(E)
Thermal insulation products — Exterior insulation and
finish systems (EIFS) —
Part 3:
Design requirements
WARNING — The use of this document can involve hazardous materials, operations and
equipment. It does not purport to address all the health and safety considerations associated
with its use.
1 Scope
This document specifies the design requirements, selection and application of exterior insulation and
finish systems (EIFS) for use by building designers, building code officials, product manufacturers and
contractors in order to sustain the installed performance and durability of EIFS.
NOTE This document does not address all aspects related to EIFS design, selection and use. A working
knowledge of applicable regional building codes and regulations is helpful when working with this document.
There could be other considerations for specific installations that are not addressed by this document.
This document contains design requirements for the design and installation of an EIFS as a wall cladding
system. The document includes selection of materials that meet the requirements of ISO 17738-1, and
installation requirements in accordance with ISO 17738-2 and covers the interfaces between EIFS and
other building assemblies and components.
This document refers to adhesively fastened systems, although mechanical fastening could be required
in specific circumstances (refer to Annex A). For information on EIFS resiliency, refer to Annex B.
This document does not specify the structural design of the substrate to which the EIFS is attached, nor
does it provide design requirements when the installation of EIFS uses mechanical fasteners.
This document is applicable to new and retrofit EIFS installations.
2 Normative reference
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.
ISO 7345, Thermal performance of buildings and building components — Physical quantities and definitions
ISO 9229, Thermal Insulation — Vocabulary
ISO 17738-1, Thermal insulation products — Exterior insulation and finish systems — Part 1:
Materials and systems
ISO/ 17738-2, Thermal insulation products — Exterior insulation and finish systems (EIFS) — Part 2:
Installation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7345, ISO 9229, ISO 17738-1,
ISO 17738-2 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
environmental se
...