Fire Safety Innovations in Timber Construction
Timber construction is gaining traction in New Zealand, driven by its sustainability and aesthetic appeal. As the country strives to meet carbon emission reduction targets, timber is increasingly being used in construction projects where concrete and steel were traditionally specified. However, timber’s combustibility presents unique fire safety challenges that must be addressed to ensure the safety and integrity of these structures. This article explores the latest fire safety innovations in timber construction, drawing on insights from local sources and industry experts.
The Rise of Timber Construction in New Zealand
Timber construction is experiencing a renaissance in New Zealand, particularly in the commercial, industrial, and multi-storey sectors. The use of mass timber materials, such as Cross Laminated Timber (CLT), Glue Laminated Timber (Glulam), and Laminated Veneer Lumber (LVL), is becoming more prevalent due to their low carbon footprint and the use of local, sustainable materials.
According to Timber Unlimited, a non-profit organisation promoting timber use in construction, mass timber buildings offer significant environmental benefits but require careful consideration of fire safety due to the combustible nature of wood.
Key Fire Safety Concerns in Timber Construction
1. Increased Fire Load
One of the primary concerns with mass timber buildings is the increased fire load. Large areas of exposed structural timber can significantly contribute to the fire load, potentially doubling the fuel available for combustion compared to traditional materials like concrete and steel.
2. Charring and Structural Integrity
While timber can char on the surface, providing an insulating layer that protects the underlying wood, charring can continue even after a fire appears to be extinguished. This ongoing charring can compromise the structural integrity of the building, posing a risk to both occupants and firefighters.
3. Decreased Compressive Strength
The compressive strength of wood decreases with temperature, starting at temperatures below 100°C. This reduction in strength can affect the load-bearing capacity of timber structures during a fire, necessitating additional fire safety measures.
Fire Safety Innovations and Solutions
1. Fire-Resistant Treatments
One of the key innovations in timber construction is the development of fire-resistant treatments. These treatments can be applied to timber surfaces to slow down the spread of flames and reduce the rate of charring.
Case Study: The BRANZ research project on the fire-safe use of timber highlighted the importance of fire-resistant treatments in enhancing the fire performance of timber products. The study found that treated timber could achieve performance criteria equivalent to non-combustible materials in certain applications.
2. Encapsulation Systems
Encapsulation systems involve covering timber elements with non-combustible materials, such as gypsum plasterboard, to protect them from direct exposure to fire. This method can significantly enhance the fire resistance of timber structures.
Expert Insight: According to the New Zealand Building Code, using protective linings like gypsum plasterboard in light timber-framed structures can provide excellent fire resistance and meet the required performance criteria.
3. Enhanced Building Codes and Guidelines
The New Zealand Building Code does not specifically address the extensive use of mass timber in multi-storey buildings. To bridge this gap, organisations like Timber Unlimited and Fire and Emergency New Zealand have developed guidance documents to support compliant fire designs for timber buildings.
Case Study: The Timber Unlimited Advanced Workshop provided clarity on developing compliant fire designs for timber buildings. The workshop highlighted the importance of early engagement with fire engineers and building control officers to ensure that fire safety measures are integrated into the design process.
4. Passive Fire Protection
Passive fire protection involves designing buildings to contain fires and prevent their spread. This can include measures such as compartmentalisation, fire-rated walls and floors, and the use of fire-resistant materials.
Expert Insight: BRANZ’s research into the passive fire protection of CLT has provided valuable insights into international practices and methods for enhancing the fire safety of mass timber buildings. These findings are being used to develop publishable guidance for New Zealand’s construction industry.
5. Fire Performance Testing
Ongoing research and testing are crucial for understanding the fire performance of timber products and developing effective fire safety measures. This includes testing the fire spread performance of engineered wood products (EWPs) and evaluating the fire resistance of mass timber joints.
Case Study: BRANZ’s study on the fire performance of mass timber joints found that the type and thickness of EWPs significantly impact their fire resistance. The research identified specific design considerations that can enhance the fire safety of timber structures.
The Role of Technology in Fire Safety
Advancements in technology are playing a significant role in improving fire safety in timber construction. Innovations such as computer modelling and simulation, real-time fire monitoring systems, and advanced fire suppression technologies are being integrated into timber buildings to enhance their safety.
Expert Insight: Dr Andy Buchanan, a leading structural engineer and fire safety expert, emphasises the importance of leveraging technology to design and construct fire-safe timber buildings. His work with PTL Structural and Fire in Christchurch focuses on integrating advanced fire safety measures into timber construction projects across New Zealand.
Timber construction offers significant environmental benefits and is becoming increasingly popular in New Zealand. However, the combustible nature of timber presents unique fire safety challenges that must be addressed to ensure the safety and integrity of these structures. By leveraging fire-resistant treatments, encapsulation systems, enhanced building codes, passive fire protection, and ongoing research and testing, the construction industry can mitigate fire risks and promote the safe use of timber in building projects.
As the field of timber construction continues to evolve, it is essential for designers, engineers, and builders to stay informed about the latest fire safety innovations and best practices. By doing so, they can contribute to the development of sustainable, fire-safe timber buildings that meet the needs of modern society while reducing the environmental impact of construction.