ISO 7728:2026

Typical horizontal joints between an external wall of prefabricated ordinary concrete components and a concrete floor — Properties, characteristics and classification criteria

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.

Assemblages horizontaux courants entre une façade en composants préfabriqués en béton ordinaire et un plancher en béton — Propriétés, caractéristiques et éléments de la classification

General Information

• Status: Published
• Publication Date: 15-Mar-2026
• ICS: 91.080.40 - Concrete structures
• Technical Committee: ISO/TC 59/SC 19 - Prefabricated building
• Drafting Committee: ISO/TC 59/SC 19 - Prefabricated building
• Current Stage: 6060 - International Standard published
• Start Date: 16-Mar-2026
• Due Date: 19-Jul-2026
• Completion Date: 16-Mar-2026

Relations

• Revises: ISO 7728:1985 - Typical horizontal joints between an external wall of prefabricated ordinary concrete components and a concrete floor — Properties. characteristics and classification criteria
• Effective Date: 23-Sep-2023

Overview

ISO 7728:2026 establishes standardized requirements for typical horizontal joints formed between external walls made of prefabricated ordinary concrete components and concrete floors. The standard focuses on specifying the properties, characteristics, and classification criteria for these joints in both public and private buildings, including dwellings, offices, schools, and hospitals. It provides guidance on non-structural performance aspects of joints, such as thermal insulation, acoustics, weatherproofing, fire resistance, appearance, and durability, but explicitly excludes characteristics related to the load-bearing capacity or structural behavior of the building.

By clarifying design conventions and minimum performance requirements, ISO 7728:2026 supports professionals in the construction industry, including architects, engineers, and building product manufacturers, aiming to optimize building performance and durability.

Key Topics

• Thermal Performance: Requirements for limiting heat transfer through joints to reduce energy losses and prevent condensation. Surface temperature factors and thermal heterogeneity coefficients are addressed for maintaining internal comfort and avoiding thermal bridging.
• Acoustical Insulation: Specifies acoustic insulation metrics (such as R values) to minimize sound transmission between spaces separated by a concrete floor, following international standards for measurement and performance.
• Air and Water Tightness: Outlines methods for ensuring joints are resistant to air infiltration and water penetration, critical for energy efficiency, durability, and the prevention of water ingress.
• Fire Resistance: Sets out criteria for joint materials and construction to prevent the passage of flames, smoke, and toxic gases, ensuring safety in fire scenarios.
• Durability and Maintenance: Stipulates that jointing materials should match the expected service life of panels, with provisions for regular inspection, maintenance, and possible replacement of degradable elements.
• Appearance and Compatibility: Recommends measures to preserve internal and external aesthetics and to account for dimensional tolerances, ensuring joints accommodate movements or changes due to environmental factors.

Applications

The standardized approach provided by ISO 7728:2026 is applicable across a wide range of building types and sectors:

• Public and Private Buildings: Suitable for residential, commercial, educational, and healthcare projects using prefabricated concrete construction techniques.
• Prefabricated Building Systems: Streamlines the integration of prefabricated wall panels and floors by offering clear joint performance requirements.
• Energy-Efficient and Sustainable Design: Supports better building envelope performance, contributing to lower utility costs and improved occupant comfort by addressing air permeability, water tightness, and thermal bridging.
• Fire Safety Upgrades: Offers practical criteria for upgrading joint fire resistance in new builds or refurbishments.
• Building Maintenance and Lifecycle Planning: Guides planning for inspections, maintenance, and replacement cycles of jointing materials to ensure long-term building envelope integrity.

Related Standards

ISO 7728:2026 references and complements several other international standards in building construction:

• ISO 6589 - Laboratory test methods for assessing air permeability of joints.
• ISO 717-1 & ISO 16283-1 - Rating and field measurement of sound insulation in buildings.
• ISO 13788 - Methods for assessing risk of surface condensation.
• ISO 10211 - Detailed calculation of heat flows and surface temperatures in building components.
• ISO 9972 - Determination of air permeability of buildings by fan pressurization.
• ISO 2445, ISO 3447, ISO 6511 - General principles and modular coordination for joints in building.

For vertical joints in concrete wall assemblies, ISO 7729 provides corresponding requirements. Adhering to ISO 7728:2026 alongside these supporting standards facilitates harmonized and high-performance prefabricated concrete building envelopes.

Standards Content (Sample)

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
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
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
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.
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO’s adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
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
...