- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 13 Apr 2018
The term ‘sacrificial timber’ is used to refer to timber in a structural assembly that is oversized purposely as a means of enhancing its fire resistance. Because timber burns at a regular and measurable rate, exposed timber sections can be designed with an additional sacrificial timber – with an increased width and/or depth – that will char slowly and protect the inner timber from fire damage.
The outer surface of a timber element will char, and usually temperatures at the surface in excess of 350°C will be necessary for flaming to occur. The charred portion of the timber acts as an insulator and, although some will be irreparably damaged (or ‘sacrificed’), the main timber retains its stability and structural integrity.
Sacrificial timber can often be a design solution if a solid timber member is to be exposed – either fully or partly – or if full fire resistance cannot be provided by plasterboard insulating materials.
The density, and therefore the charring rate, of the timber element will determine the required quantity of sacrificial timber.
Notional charring rates (the charring rates apply to each face exposed to fire):
|MATERIAL||CHARRING RATE ßn (mm/min)|
|Softwood glulam and laminated veneer lumber (LVL)||0.7|
|Hardwood timber and hardwood glulam||0.55|
2 x 20 x 0.8 = 32 mm
The width and depth of the element would require 32 mm of sacrificial timber.
 Related articles on Designing Buildings Wiki
Featured articles and news
The Chartered Quality Institute explain the pathway to success for organisations implementing management systems.
An introductory article looking at where a duty of care can arise in the construction industry.
House of Lords committee encourages the use of off-site manufacturing in new report.
Computational fluid dynamics (CFD) can go some way to show the impact of new buildings on their surroundings.
The shortlist for the 2018 prize for the UK's best new building is revealed.
Amendment to Bill aims to provide councils with greater powers to increase tax premiums on empty homes.
As the latest summer blockbuster 'Skyscraper' is released, we look at some of the best uses of buildings in film.
Read our introductory article on how to layout a building.
New cross-party report calls for combustible cladding ban to be extended to all high-rise residential buildings.
Dr Nicholas Falk, director of the URBED Trust, explains why metro cities are the future of urbanisation.