Initial Study on Thatched Roofing Assembly Ignition Vulnerabilities to Firebrand Showers

Area of Science:

• Fire Science
• Building Materials Science
• Historical Preservation

Background:

• Thatched roofing assemblies are susceptible to ignition from external fire sources.
• Large outdoor fires pose a significant risk to structures with traditional roofing materials.
• Understanding ignition mechanisms is crucial for protecting vulnerable heritage buildings.

Purpose of the Study:

• To investigate the fundamental ignition mechanisms of thatched roofing assemblies exposed to firebrands.
• To analyze the impact of wind speed on firebrand ignition and flame spread in thatch.
• To provide data for developing protective measures for historical thatched structures.

Main Methods:

• Experiments were conducted using a reduced-scale continuous-feed firebrand generator.
• A wind facility was employed to simulate realistic fire exposure conditions.
• Wind speeds were systematically varied between 3 m/s and 6 m/s.

Main Results:

• Firebrands were observed to penetrate the thatched roofing assembly, leading to ignition.
• Internal ignition often occurred, remaining unseen from the exterior initially.
• Penetration by firebrands resulted in rapid flame spread within the thatch.

Conclusions:

• Firebrand penetration is a critical factor in the ignition of thatched roofs.
• The findings highlight the vulnerability of thatched structures to ember attacks during wildfires.
• This research supports the development of enhanced fire safety strategies for historical thatched buildings, including UNESCO World Heritage sites.