ISO/TR 24188:2025

Technical
Report
ISO/TR 24188
Second edition
Large outdoor fires and the built
2025-02
environment — Global overview
of different approaches to
standardization
Grands incendies extérieurs et environnement bâti —
Vue d'ensemble des différentes approches en matière de
normalisation
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Ignition scenarios . 3
5 Regulation principle and strategies . 4
5.1 Japan .4
5.2 California State Building Code (US) .4
5.3 NFPA 1144, Standard for Reducing Structure Ignition Hazards from Wildland Fire (US) .5
5.4 International Wildland Urban Interface Code (IWUIC) .5
5.5 France .5
5.6 Australia .5
6 Standard tests approaches . 5
6.1 Overview .5
6.2 Approach for roofing assemblies.6
6.2.1 Japan .6
6.2.2 North America .6
6.2.3 France .6
6.2.4 Australia .6
6.3 Approach for exterior walls and facades .7
6.3.1 Japan .7
6.3.2 North America .8
6.3.3 France .8
6.3.4 Australia .8
6.4 Other building elements .9
6.4.1 Vents .9
6.4.2 Decks .9
6.4.3 Eaves .9
6.4.4 Windows .10
7 Additional provisions .10
7.1 Reaction-to-fire — California .10
7.2 Reaction-to-fire — France.10
8 Summary of scenarios and tests .10
Annex A (informative) Precise description of tests for roof performance defined in the
European Standard CEN/TS 1187 .13
Bibliography .16

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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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 document 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 92, Fire safety.
This second edition cancels and replaces the first edition (ISO/TR 24188:2022), which has been technically
revised.
The main changes are as follows:
— various term entries in Clause 3 have been modified;
— Figure 2 has been replaced with a new diagram;
— the Bibliography has been updated.
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.

iv
Introduction
Large outdoor fires have the potential to negatively impact the built environment.
Examples of such fires are:
— wildland-urban interface (WUI) fires (wildland fires that spread into communities; this type of fire has
become a global problem);
NOTE Once a WUI fire reaches a community, a large urban fire can develop.
— post-earthquake fires (large urban fires that potentially occur after an earthquake);
— tsunami-generated fires (fires potentially generated from tsunamis);
— volcano-generated fires (fires potentially generated from volcanic activity); and
— fires that occur in informal settlements.
This document provides an overview of approaches to standardization for lessening the destruction on the
built environment caused by such fire exposure. Some of the test methods outlined in this document have
been developed in the context of building fires and extrapolated to external fire exposures. Evacuation is
not included as there are no known approaches to standardization as the present time.

v
Technical Report ISO/TR 24188:2025(en)
Large outdoor fires and the built environment — Global
overview of different approaches to standardization
1 Scope
This document provides a review of global testing methodologies related to the vulnerabilities of buildings
from large outdoor fire exposures. It also provides information on land use management practices.
2 Normative references
There are no normative references in this document.
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/
3.1.1
bushfire
unplanned fire in a vegetated area, as opposed to an urban area
Note 1 to entry: Used primarily, but not exclusively, in Australia, New Zealand and Africa.
Note 2 to entry: For further information, see Reference [42].
3.1.2
direct flame contact
flame impinging on building systems and materials
Note 1 to entry: For further information, see Reference [43].
3.1.3
evacuation
dispersal or removal of people from dangerous areas and their arrival at a place of relative safety
Note 1 to entry: For further information, see Reference [44].
3.1.4
post-earthquake fire
fire which occurs after an earthquake
3.1.5
firebrand
airborne object capable of acting as an ignition source and carried for some distance in an airstream
Note 1 to entry: For further information, see Reference [45].

3.1.6
informal settlement
unplanned settlement or area where housing is not in compliance with current planning and building
regulations (unauthorized housing)
[SOURCE: Glossary of Environment Statistics, Studies in Methods, Series F, No. 67, United Nations, New York,
[46]
1997]
3.1.7
large outdoor fire
urban fire, tsunami-generated fire, volcano-generated fire, WUI fire, wildland fire, or informal settlement
fire, where the total burnou
...