ISO 20812:2026

International
Standard
ISO 20812
First edition
Thermal insulation products for
2026-01
buildings — Cellular glass products
— Specification
Produits d'isolation thermique pour les bâtiments — Produits de
verre cellulaire — Spécification
Reference number
© ISO 2026
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms. 2
5 Characteristics . 3
5.1 General .3
5.2 Thermal conductivity .3
5.3 Compression strength .4
5.4 Dimensions .4
5.5 Bending strength .5
5.6 Point load .5
5.7 Tensile strength perpendicular to faces .5
5.8 Dimensional stability .6
5.9 Short-term water absorption . .6
5.10 Long-term water absorption .6
5.11 Water vapour transmission .6
5.12 Fire behaviour .6
5.13 Apparent density .7
6 Test methods . 7
6.1 Sampling .7
6.2 Conditioning.7
6.3 Testing .7
6.3.1 Test methods and specimen requirements .7
6.3.2 Thermal conductivity .8
7 Designation code . . 8
8 Marking and labelling . 9
Annex A (normative) Factory production control (FPC) . 10

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
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rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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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, components and systems.
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
International Standard ISO 20812:2026(en)
Thermal insulation products for buildings — Cellular glass
products — Specification
1 Scope
This document specifies the requirements and test methods for factory-made cellular glass products which
are used for thermal insulation of buildings. The products are manufactured in the form of slabs, faced or
unfaced boards, and one-sided blocks.
Products covered by this document are also used in prefabricated thermal insulation systems and composite
panels. The performance of systems incorporating these products is not covered.
This document describes product characteristics and test methods, designation code, marking and labelling.
This document does not apply to:
— products with a declared thermal conductivity greater than 0,056 W/(m K) at 25 °C;
— products for the insulation for the building equipment and industrial installations.
This document does not specify the required level of a given property to be achieved by a product to
demonstrate fitness for purpose in a particular application. Specific requirements agreed between
the purchaser and the supplier, e.g. type, dimensions and forms, regulatory compliance and inspection
requirements or certification requirements are outside the scope of this document.
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 1182, Reaction to fire tests for products — Non-combustibility test
ISO 1716, Reaction to fire tests for products — Determination of the gross heat of combustion (calorific value)
ISO 8301, Thermal insulation — Determination of steady-state thermal resistance and related properties —
Heat flow meter apparatus
ISO 8302, Thermal insulation — Determination of steady-state thermal resistance and related properties —
Guarded hot plate apparatus
ISO 9229, Thermal insulation — Vocabulary
ISO 10456, Building materials and products — Hygrothermal properties — Tabulated design values and
procedures for determining declared and design thermal values
ISO 11925-2, Reaction to fire tests — Ignitability of products subjected to direct impingement of flame — Part 2:
Single-flame source test
ISO 12344, Thermal insulating products for building applications — Determination of bending behaviour
ISO 12570, Hygrothermal performance of building materials and products — Determination of moisture content
by drying at elevated temperature
ISO 12572, Hygrothermal performance of building materials and products — Determination of water vapour
transmission properties — Cup method

ISO 16535, Thermal insulating products for building applications — Determination of long-term water
absorption by immersion
ISO 29465, Thermal insulating products for building applications — Determination of length and width
ISO 29466, Thermal insulating products for building applications — Determination of thickness
ISO 29467, Thermal insulating products for building applications — Determination of squareness
ISO 29468, Thermal insulating products for building applications — Determination of flatness
ISO 29469, Thermal insulating products for building applications — Determination of compression behaviour
ISO 29470, Thermal insulating products for building applications — Determination of the apparent density
ISO 29472, Thermal insulating products for building applications — Determination of dimensional stability
under specified temperature and humidity conditions
ISO 29765, Thermal insulating products for building applications — Determination of tensile strength
perpendicular to faces
ISO 29767, Thermal insulating products for building applications — Determination of short-term water
absorption by partial immersion
ISO 29769, Thermal insulating products for building applications — Determination of behaviour under point
load
ISO 29771, Thermal insulating materials for building applications — Determination of organic cont
...