ISO 7728:2026

International
Standard
ISO 7728
Second edition
Typical horizontal joints between
2026-03
an external wall of prefabricated
ordinary concrete components
and a concrete floor — Properties,
characteristics and classification
criteria
Assemblages horizontaux courants entre une façade en
composants préfabriqués en béton ordinaire et un plancher
en béton — Propriétés, caractéristiques et éléments de la
classification
Reference number
© ISO 2026
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ii
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Properties of joints and agents to which they are exposed . 2
4.1 Properties .2
4.2 Agents to which joints are exposed .3
5 Characteristics of joints . 4
5.1 General .4
5.2 Thermal transmission between internal and external environments .4
5.3 Influence of joint on acoustical insulation of the floor .4
5.4 Air permeability of joints (between either external and internal environments, or
spaces separated by the floor) .4
5.5 Water tightness .4
5.5.1 General .4
5.5.2 Sealing and waterproofing measures of joints . .6
5.5.3 Overlap .7
5.5.4 Capillary break .7
5.5.5 Air tightness .7
5.6 Water vapour condensation on the internal face of the wall and floor in the vicinity of
the joint .7
5.7 Transmission of forces .8
5.7.1 Load-bearing external wall, self-supporting external wall .8
5.7.2 Supported external wall .8
5.8 Fire resistance .8
5.9 Emission of gases or toxic fumes in the event of fire.8
5.10 Internal and external appearance .8
5.11 Durability .8
6 Other indications to be given . 9
6.1 Maintenance of jointing materials .9
6.2 Replacement of degradable jointing materials .9
6.3 Dismantling and reassembling components .9
7 Dimensional coordination . 9
8 Classification criteria . 9
Bibliography .11

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
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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This document was prepared by Technical Committee ISO/TC 59, Buildings and civil engineering works,
Subcommittee SC 19, Prefabricated building.
This second edition cancels and replaces the first edition (ISO 7728:1985), which has been technically
revised.
The main changes are as follows:
— update of reference documents;
— addition of terminological entries for “surface temperature coefficient” (3.4), “fire resistance” (3.5) and
“concrete sandwich board” (3.6);
— addition of Tables 1, 2 and 3, integrating 4.1 and 5.5.2;
— addition of 5.2, regarding the indexes of thermal transmission;
— addition of 5.3, refining the data and measurement of sound insulation R value;
— addition of Figure 2, integrating Clause 5;
— redrafting of 5.5.3 to describe the overlap range in different building environments;
— redrafting of 5.5.4 to describe the setting of capillary fracture width between the fracture surface and
the vertical plane;
— addition of μ value calculation reference in 5.6;
— addition of joint fillers to the condensation coefficient inside, fire resistance, and emission of gases or
toxic smoke in 5.6, 5.8 and 5.9;
— addition of explanation of heterogeneity coefficient, Q, in 5.10;
— redrafting the text describing durability in 5.11;

iv
— addition of description of maintenance of jointing materials in 6.1;
— addition of the characteristics of joints dimension in Clause 7.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
Introduction
This document outlines a convention for designers about jointing an external wall made of ordinary
prefabricated concrete components and a concrete floor.
This convention refers to standardized methods for the determination of the properties of the joint. However,
the methods for some of these properties are not elaborated. Given the importance of these properties,
solutions are proposed and both experience and laboratory studies have shown to be satisfactory under the
usual conditions. It should be noted that these solutions are not the only viable options.

vi
International Standard ISO 7728:2026(en)
Typical horizontal joints between an external wall of
prefabricated ordinary concrete components and a concrete
floor — Properties, characteristics and classification criteria
1 Scope
This document specifies the properties and characteristics of typical horizontal joints between two
prefabricated ordinary concrete external wall components and a concrete floor.
However, the characteristics of joints, which are involved in the structural behaviour of buildings, are not
specified in this document.
This document is applicable to all public or private buildings, used as dwellings, offices, educational or
hospital premises.
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.
ISO 6589, Joints in building — Laboratory method of test for air permeability of joints
ISO 717-1, Acoustics — Rating of sound insulation in buildings and of building elements — Part 1: Airborne
sound insulation
ISO 16283-1, Acoustics — Field measurement of sound insulation in buildings and of building elements — Part 1:
Airborne sound insulation
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
load-bearing external wall
external wall, the role of which includes the stability of the building, that, in additional to self-weight, wind
loads and similar, also support floor loads (wholly or in part), transmitting them directly or indirectly to the
foundation
3.2
self-supporting external wall
external wall that does not form part of the load bearing structure and the weight of which is transmitted to
the foundation
3.3
supported external wall
external wall that does not form part of the load-bearing structure and the weight of which is transmitted
back to the load-bearing structure of the building
3.4
temperature factor
ratio of the difference between the minimum surface temperature at the joint and the indoor air temperature
and the difference between the outdoor air temperature and the indoor air temperature
3.5
fire resistance
measure of the ability of a material or structure to resist collapse, flame penetration, and excessive
temperature rise on the unexposed surface under specified conditions of test
3.6
concrete sandwich board
prefabricated concrete exterior wall panel with precast concrete inner and outer layer that are structurally
connected, and insulation materials filled in the middle
4 Properties of joints and agents to which they are exposed
4.1 Properties
For joints, the necessary properties listed in Table 1 shall be considered. The optional properties listed in
Table 2 should be considered.
Table 1 — Necessary properties of joints
Application
No. Property name Description
environment
a Thermal To limit thermal losses (between the internal and external Various climatic
conductivity environments). conditions
b Soundproofing To limit sound transmission (between the spaces separated by Various indoor
the floor, if any). environments
c Air-tightness To provide satisfactory resistance to air penetration. Various climatic
conditions
d Water and snow To ensure water-tightness and snow tightness between the Various climatic
tightness exterior and interior and, for water and other liquids, conditions
between the spaces separated by the floor.
e Light blocking To prevent the passage of light (between spaces separated by the Various lighting
floor, if any). conditions
f Non-toxic and The joints should be non-toxic and not emit odours (odours Various indoor
odour-free emitted by jointing products). environments
g Anti-condensation Condensation of water vapour should not occur opposite the Various climatic
joints and in the joints on the internal face of the wall. con
...