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
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Preserving, waterproofing and decorating buildings.
Many resources for visitors aswell as new features for members.
Using technology to empower communities
The Community data platform; capturing the DNA of a place and fostering participation, for better design.
Heat pump and wind turbine sound calculations for PDRs
MCS publish updated sound calculation standards for permitted development installations.
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Heritage staff wellbeing at work survey.
A five minute introduction.
50th Golden anniversary ECA Edmundson apprentice award
Showcasing the very best electrotechnical and engineering services for half a century.
Welsh government consults on HRBs and reg changes
Seeking feedback on a new regulatory regime and a broad range of issues.