Charring rate
Charring rate, refers to depth and speed that materials burn on exposure to fire. It is a key part of calculating the fire resistance of different timber elements in buildings, particularly structural elements. The charring rates are calculated by measuring the char depth, in comparison with the time material is exposed to the heat load.
EN 1995-1-2:2004 provides charring rates for different timber materials for the purposes of informing initial design. The charring rates apply to each face of the timber that is exposed to fire. For example, if a softwood element is exposed on all four of its sides to 20 minutes of fire: 2 x 20 x 0.8 = 32 mm
Example different material charring rates ßn (mm/min)
- Softwood timber 0.8
- Softwood glulam and laminated veneer lumber (LVL)0.7
- Western Red Cedar (390 kg/m³) 0.8
- Hardwood timber and hardwood glulam 0.55
- Oak and Sapele (>640 kg/m³) 0.5
It is important to note that the process of charring releases air and oxygen and chemically restructures timber to actually make it more fire resistant, this process can also be carried out mechanically where wood is burned evenly and at a constant rate to improve performance.
[edit] Related articles on Designing Buildings
Featured articles and news
Boiler Upgrade Scheme and certifications consultation
Summary of government consultation which closes 11 June 2025.
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
CIOB Construction Manager of the Year 2025
Just one of the winners at the CIOB Awards 2025.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.
Construction Products Reform Green Paper and Consultation
Still time to respond as consultation closes on 21 May 2025.
Resilient façade systems for smog reduction in Shanghai
A technical approach using computer simulation and analysis of solar radiation, wind patterns, and ventilation.