Since time immemorial, humans have used wood to construct their shelters and homes. These structures became increasingly complex over time, but wood has remained a critical component of architecture and construction. Today, owing largely to growing concerns about climate change and carbon emissions, wood has regained prominence as a critical future building material, if used wisely and sustainably. Wood’s structural performance characteristics make it suitable for a wide variety of applications, ranging from the light-duty repetitive framing found in low- and mid-rise structures to the larger and heavier, frequently hybrid systems used to construct arenas, offices, universities, and other structures with long spans and tall walls.
For floor and wall framing, mass timber is a category of framing that frequently employs large panelized solid wood constructions such as cross-laminated timber (CLT), nail laminated timber (NLT), dowel laminated timber (DLT), and glued laminated timber (glulam) panels. It provides exceptional stability and strength, making wood a viable alternative to steel and concrete in a variety of applications, including those requiring taller structures. As timber construction continues to grow in popularity, it is critical to understand wood’s demonstrated ability to resist fire. Fire is a threat to all structures and construction sites, regardless of their construction material. Fires start in the contents and furnishings we bring into our homes and offices, and they can occur in structures made of concrete, steel, masonry, or wood, and all building materials suffer adverse effects from prolonged exposure to flames. Buckles in steel, concrete spalls, and wood burns. What matters most is adhering to code in order to ensure the safety of occupants and first responders.
Through the insulation of inner layers, mass timber provides inherent fire resistance. When exposed to fire, wood burns on the exposed surface, forming a natural protective charred layer. Char acts as an insulator, delaying the start of heating in the wood’s core. Due to the solid block structure of mass timber, air and fire cannot travel freely. Char accumulates at a predictable rate (1.5in/hr), which retards combustion and fire spread.
In recent years, robust mass timber fire testing has established the safety of this sustainable, renewable building material. To be precise, the International Code Council established a committee of industry experts in 2016 to examine and propose appropriate standards for CLT walls, floors, and solid wood structures, owing to their structural and fire-resistant characteristics. This link will keep you updated on any developments on this subject. To assess the fire behavior of these building systems, a series of rigorously monitored fire tests was developed, which provided critical data for the revision of fire codes and regulations for tall wooden structures. Each of the five simulated materials and situations is intended to mimic real-world conditions in five identical environment scenarios. This playlist includes a three-minute video highlighting the highlights of each test.
Mass timber not only complies with prescribed fire and safety codes, but often exceeds them. In a fire test, a 7-inch-thick (approximately 18-cm) plaster-coated Cross Laminated Wood (CLT) wall lasted 3 hours and 6-minutes. This result exceeds current fire code requirements by an hour.
Fire Protection in Occupied Structures
Fire departments are called to extinguish fires nearly three times more frequently in non-sprinklered buildings than in buildings with adequate fire protection measures. Over 96 percent of the time, fires in sprinkler-protected buildings were smaller and contained to a single room. Additional critical fire safety precautions include the following:
Advisory Services to Fire Departments
Developing Firewalls
Utilization of Gypsum Encapsulation
Automatic Sprinkler System Installation
Putting Fire Detection Systems in Place
Creating Extensive Evacuation Plans
The increased use of exposed mass timber in multi-family and commercial structures has necessitated a better understanding of these structures’ fire design procedures. Numerous mass timber products are permitted under the 2018 IBC, and multiple design routes exist for demonstrating compliance with the building code’s fire-related provisions. It is possible to design mass timber elements in such a way that a sufficient cross-section of wood remains to support the design loads for the required duration of fire exposure. This distinguishes mass timber as a truly unique building material, capable of achieving structural performance and passive fire resistance objectives for larger and taller wood structures than ever before, while also providing enhanced aesthetic value and environmental benefits.
Adhering to Fire Safety Codes Maintain functional fire suppression systems – this is a requirement for any structure, but having properly installed and maintained fire suppression systems in your warehouse is the single most important thing you can do for your structure. Deluge fire sprinklers and in-rack fire suppression systems are frequently used in warehouses. Maintain an adequate distance beneath sprinkler heads – You must have a minimum of 18 inches of space beneath all sprinkler heads, as anything higher will obstruct water flow and jeopardize your warehouse’s protection.
Allow space between pallets – if storing items on pallets, allow three inches of transverse space on all sides of each pallet and six inches of longitudinal flue space between back-to-back rows. If you’re racking pallets to store items, leave at least three inches of “transverse flue space” on either side of each rack. The term “transverse flue space” refers to the area on both sides of a stacked pallet.
Additionally, six inches of longitudinal flue space, or space between rows of back-to-back rack, must be maintained. Nota bene: the space between the loads, not the space between the pallets, is used to determine the flue space. This means that if your load extends three inches beyond the side of the pallet, you must begin measuring the flue space at that point, not at the end. If your warehouse meets the above requirements for flue space, an in-rack fire sprinkler system is unlikely to be required. However, if you rack using solid decking and shelves, if your storage configurations prevent the maintenance of flue spaces, if you store hazardous materials, or if your storage reaches a height of more than 40ft, in-rack fire sprinkler systems are strongly recommended.
Aisles that end in a dead end must be noted and cannot exceed 50ft in length. In solid piled floor storage facilities, aisle space must be maintained at a minimum of every 100ft and within 50ft of any wall. This essentially means that any area with solid piled floor storage must be located within 50 feet of an aisle. If you manually replenish your warehouse, maintain a minimum aisle width of 24 inches or half the aisle width – whichever is greater. Maintain an aisle width of at least 44 inches during mechanical restocking. Needless to say, smoking should never be permitted in a warehouse.
Throughout the facility, place “No Smoking” signs. Cylinders of liquid propane must be kept at least 20 feet away from fire exits and are limited to 300 pounds per storage facility. When counting propane tanks, empty cylinders are considered full (just to be safe). If you require additional fuel storage, ensure that the storage locations are at least 300ft apart. Consult your local fire codes for information on the following: Material handling operations that are automated, such as carousels and ASRS units Areas for battery charging Plastics Aerosols Hazardous Substances Beyond Compliance: Fire Safety in Warehouses Clearly, the recommendations above will shield you from fire marshal fines.
Even following those guidelines, however, does not ensure that you will be completely protected in the event of a fire! There are numerous factors that can affect your actual level of protection, many of which are unknown to a fire safety inspector: changes in the composition of stored products, changes in the type of packaging used, or changes in the storage configuration can all impact your level of fire protection. If you want to go beyond simply adhering to the guidelines and providing serious fire protection for your employees, you should speak with a fire protection engineer who can design a fire protection plan specifically for your warehouse’s needs. To ensure that your warehouse is completely protected from fires, follow these warehouse fire safety tips: Evacuation plans – Needless to say, every structure requires an evacuation plan.
A fire protection engineer can assist you in determining the simplest routes to all of your building’s exits and in conducting fire drills to ensure that your employees understand exactly what to do in the event of a fire. Additionally, because warehouse configurations change frequently, ensure that your employees understand that going to a “assigned” exit is less important than going to the exit that is closest to them calmly and efficiently. Fire extinguisher training – if you work in a warehouse, you will almost certainly come into contact with Class ABC or Class D fire extinguishers.
A fire protection company can provide training for all types of fire extinguishers, ensuring that everyone in your building understands how to respond quickly and effectively to a fire. Using tape to denote specific storage and staging areas on the floor. This significantly simplifies the process of establishing and enforcing proper aisle space rules. Trash accumulation – this is not something that requires the assistance of a fire protection company, but it is still critical.
Clearly, a space that is cluttered with trash is more prone to fire than one that is kept tidy. Assign adequate trash cans and the responsibility of emptying them as they fill. Additionally, you should have designated areas for unused pallets, crates, and other similar items. As a general rule, stack unused pallets no higher than six feet. To fully protect your warehouse against fires, you must go above and beyond the fire code’s minimum requirements.