Performance of Timber and CLT in Fire
The performance of timber and Cross-Laminated Timber (CLT) in fire is characterized by their predictable charring behavior, which forms a protective layer that insulates the inner core and slows structural degradation. While timber is combustible, its fire resistance can be enhanced through design, size, and protective treatments. CLT panels, due to their mass and layered construction, exhibit similar charring, providing structural stability for a certain period during fire exposure, meeting modern fire safety standards.
Performance of Timber and CLT in Fire
The performance of timber and Cross-Laminated Timber (CLT) in fire is characterized by their predictable charring behavior, which forms a protective layer that insulates the inner core and slows structural degradation. While timber is combustible, its fire resistance can be enhanced through design, size, and protective treatments. CLT panels, due to their mass and layered construction, exhibit similar charring, providing structural stability for a certain period during fire exposure, meeting modern fire safety standards.
💡 Key Takeaways
- Understand how timber and CLT respond to fire, including charring behavior and how thickness influences performance.
- Learn how CLT's layered construction affects fire resistance and residual strength during exposure.
- Identify practical design strategies to improve fire performance of timber/CLT (e.g., protective enclosures, gypsum board encapsulation, compartmentation).
- Recognize common fire-rating expectations and the tests/standards used to verify timber and CLT fire performance.
❓ Frequently Asked Questions
What is CLT and how does timber perform in fire scenarios?
Cross-Laminated Timber (CLT) is a panel made from layers of timber glued crosswise. In fire, exposed wood chars on the surface, forming an insulating layer that slows heat penetration and helps maintain structural capacity for a period when designed to meet fire ratings.
How does the char layer protect timber during a fire?
A char layer forms on the surface and acts as an insulating shield, reducing heat transfer to the inner wood. This slows pyrolysis, delaying strength loss. Charring rate depends on thickness, timber species, moisture, and panel geometry.
What design strategies improve fire safety for timber/CLT buildings?
Use fire-rated assemblies (e.g., gypsum board, intumescent coatings), design for required fire-resistance durations, protect edges/joints, ensure compartmentation, and consider protective cladding and proper detailing to maintain structural redundancy.
How is fire performance of timber/CLT tested and rated?
Standard fire tests expose components to a fire curve to evaluate when structural function is lost. Results yield fire resistance ratings (minutes) and inform code compliance. CLT and timber have published data on char rates and residual strength.