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MATERIALS 45
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methods to demonstrate structural adequacy during and after which establishes the general structural design principles and
fire, confidence in the underlying assumptions depends on load capacity calculations for timber under ambient conditions.
how well those methods represent the dominant physical Similar to Eurocode 5, the standard does not explicitly
processes in each product. address CLT design, and therefore, CLT fire performance
For Glulam, simplified methods are often sufficient; for assessment in Australia and New Zealand typically relies on
CLT, adhesive behaviour, lamella thickness, and interlaminar manufacturer data, full-scale fire testing, or supplementary

heat transfer can govern residual capacity in ways that require technical publications.
careful interpretation of test data and, in many cases, a more In Sweden, the fire resistance design of timber structures
explicit modelling of layer interactions. is governed by the Swedish Building Regulations, Boverkets
byggregler, used in conjunction with Eurocode 5. Swedish
International Fire Design Codes & Standards practice extends these European provisions through national
In Europe, the fire design of timber structures is primarily guidelines and design aids developed by Swedish Wood.
governed by Eurocode 5, EN 1995-1-2, which establishes The Glulam Handbook Volumes 2 and 3 provide detailed
harmonised methods for evaluating fire resistance, charring guidance on the fire resistance design of Glulam elements,
behaviour, and load-bearing capacity of solid timber and referencing Eurocode 5 for calculating charring rates, residual

Glulam elements. section geometry, and load-bearing capacity.
Eurocode 5 specifies two analytical approaches: the Unlike Eurocode 5 and AS/NZS 1720.4, the CLT Handbook
Simplified Method (SM), which uses prescribed charring rates published by Swedish Wood provides comprehensive procedures
and residual section parameters, and the Advanced Calculation for assessing the fire resistance of CLT elements, accounting
Method (ACM), which employs temperature-dependent thermal- for charring behaviour, adhesive performance, and lamella
mechanical modelling to predict fire-induced behaviour with configuration.
greater accuracy. The handbook distinguishes between melamine-urea-

However, Eurocode 5 does not explicitly include provisions formaldehyde (MUF) adhesives, which are non-delaminating,
for CLT elements, as the material was not yet standardised and polyurethane (PUR) adhesives, which may delaminate
at the time of publication. under heat, influencing charring progression.
Consequently, CLT fire design in Europe typically relies on In the US, the fire design of timber structures is governed
national annexes, technical assessments, and supplementary
design documents such as the CLT Handbook and research-
based guidelines, which extend Eurocode principles to include
CLT-specific charring, delamination, and adhesive performance Jacobs School of Engineering
behaviour.

In Australia and New Zealand, the fire design of timber
structures is primarily governed by AS/NZS 1720.4, which
provides analytical and empirical procedures for determining the
fire resistance, charring behaviour, and residual load-bearing
capacity of solid timber, Glulam, laminated veneer lumber
(LVL), and plywood members.
This standard operates in conjunction with AS 1720.1,