Table of Contents
Cold Formed Steel and Fire Safety
Cold formed steel (CFS) excels in fire prevention due to its non-combustible nature, meaning it doesn't ignite or contribute to fire spread. This makes it an optimal choice for fire-resistant building structures. Additionally, CFS meets or exceeds fire-resistance ratings mandated by the International Building Code (IBC) and National Fire Protection Association (NFPA) codes. These codes require the use of fire-resistant materials and construction techniques, enhancing overall building safety. Using CFS not only helps achieve compliance but also significantly boosts fire safety in construction projects.
Fire Resistant Materials
Incorporating additional fire-resistant materials is a critical aspect of any fire prevention strategy in steel construction projects:
Fire-Resistant Gypsum Board
Fire-resistant gypsum boards, also known as drywall, include specialized panel types like Type X and Type C drywall which are designed to enhance a structure's fire resistance. Type X boards contain glass fibers for added strength and can provide fire ratings of up to one hour. Type C boards, with additional additives, offer superior performance and can achieve fire ratings of up to two hours. These boards are often used to cover steel framing, significantly improving the overall fire resistance of buildings and ensuring compliance with safety standards and building codes.
Intumescent Coatings for Steel Framing
Intumescent coatings expand when exposed to heat, forming an insulating layer that protects steel from high temperatures. This reaction helps prevent structural damage and maintains the building's structural integrity during a fire. These coatings can also block the passage of air and smoke. Products like ClarkDietrich's BlazeFrame Tape offer a convenient, adhesive-backed solution for fire protection. Intumescent coatings are a crucial component in fire protection strategies, meeting stringent standards and enhancing safety in steel structures.
There are two main types of intumescent coatings: thin-film and thick-film. Thin-film coatings, typically used in commercial and residential buildings, can be applied directly to steel framing in layers using spraying or brushing techniques, providing up to 120 minutes of fire resistance. Thick-film coatings, often used in industrial settings, are applied in heavier layers and offer longer protection times. Both types effectively insulate steel, but their application depends on the required fire rating and environmental conditions.
BlazeFrame Tape- convenient adhesive backing.
Cementitious Coatings / Spray-Applied Fire-Resistive Material (SFRM)
Cementitious coatings, also known as spray-applied fire-resistive materials (SFRM), are an alternative to intumescent coatings for protecting structural steel. These materials, including mineral fiber and other cementitious compounds, are sprayed directly onto beams, columns, girders, and floor/roof decks. SFRMs expand and insulate steel to prevent failure from high temperatures. They are typically used in concealed areas, such as above ceilings or behind drywall.
Proper application is crucial, requiring strict adherence to manufacturer instructions for mixing and applying. Surfaces must be cleaned of dirt, oil, and loose scale to ensure proper adhesion, although light corrosion is usually acceptable. It's common for steel to arrive pre-primed, so using fireproofing materials approved for application over primers is essential. Research indicates that painting structural steel isn't necessary when protected by SFRMs.
Spray application of cementitious SFRM coating in a large office complex.
Innovative Fire Prevention Products
Steel framing industry-specific manufacturers have recently developed innovative products specifically designed to enhance fire safety in steel-framed buildings. For example, aluminum burn clips are engineered to fail faster than the primary structure in the event of a fire. This design approach with a prescriptive failure mode helps to stop fire from spreading throughout the entire structure, effectively adding an extra layer of protection and mitigating the risk of a fire spreading throughout a multi-unit residential structure or commercial space.
ClarkDietrich aluminum burn clip designed to allow a fire-damaged unit to collapse while maintaining the firewall barrier in place to protect adjoining units.
Concrete and Masonry for Steel Fire Protection
Concrete was once the primary material for structural steel fire protection, but its high thermal conductivity makes it less efficient. However, it's still used in composite construction, such as concrete-encased steel columns, for architectural purposes or where resistance to physical damage is needed.
The AISI provides design guidelines for steel columns encased in concrete or with precast concrete covers. Additionally, resources on using concrete masonry or brick for fire protection can be found through the National Concrete Masonry Association and the Brick Institute of America.
Compartmentalization of Structure
Compartmentalization of a structure is a vital strategy in fire prevention. By dividing a building into separate fire-resistant sections, vital structural components are temporarily protected and the spread of fire can be significantly slowed or even halted.
Firestopping
This technique involves sealing openings and utility passages in fire-rated walls and floors with fire-resistant materials. Firestopping is crucial around areas where pipes, ducts, and cables pass through walls, as these openings can provide pathways for fire to spread.
Application of intumescent sealant around ductwork.
Fire Rated Wall Assemblies
Fire-rated wall assemblies are essential components in building design, defined in Chapter 7 of the International Building Code (IBC). Here’s a breakdown of key types:
Fire Partitions
Fire partitions, typically used in corridors and dwelling units, have a minimum fire-resistance rating of 1 hour and extend from floor to ceiling. They can terminate at a rated floor or roof and are often used to subdivide areas within a building.
Fire Barriers
Fire barriers are used to separate different occupancies and control fire spread, with fire-resistance ratings ranging from 1 to 4 hours. They must extend from the floor to the underside of the roof or to another fire barrier, ensuring compartmentalization within buildings to contain fire and smoke.
Smoke Barriers
Smoke barriers are designed to prevent smoke spread and ensure safe egress, having a minimum 1-hour fire-resistance rating. They extend continuously from one exterior wall to another, creating compartments that limit smoke movement and protect exit pathways, essential for areas like hospitals and large commercial buildings. Products such as ClarkDietrich's BlazeFrame Shield (see image below) can be installed in concealed draft areas with appropriate fireblocking materials to establish a barrier between floors and prevent smoke and heat from traveling between different levels in a building. The cold formed steel geometry of BlazeFrame Shields allow the product to be quickly twisted into place and fastened with minimal cutting and notching. These shields are available in a variety of sizes to match 16" and 24" OC stud spacing and 3-5/8", 4", or 6" stud width.
ClarkDietrich BlazeFrame Shield available in the clips store is specifically designed for use in conjunction with approved fireblocking materials per section 718 of the IBC.
Fire Walls
Fire walls create separate buildings or divide large buildings into smaller fire areas with fire-resistance ratings of 2 to 4 hours. They must extend from the foundation through the roof and often include a parapet. Fire walls provide a high level of protection by ensuring that a fire in one section does not compromise the structural integrity of the entire building.
*Please note that an indicated fire resistance rating does not guarantee that a particular wall assembly will prevent spread of fire for the entire time duration. Actual emergency conditions will create different effects than lab testing.
ClarkDietrich Riptrak 1&2 hour assemblies cutaway view.
Active Fire Fighting Systems
Implementing active fire fighting systems is another essential aspect of fire prevention in steel-framed buildings. These systems can extinguish small fires or extend the time window before structural failure, increasing the chance that emergency professionals are able to contain the fire and provide assistance to building occupants.
Sprinkler Systems
Sprinkler systems are the most common fire protection solution in commercial buildings. Automatic sprinkler systems effectively control and extinguish fires, making them essential for safety. Many building codes mandate their installation in commercial spaces, and their use is increasingly spreading to residential structures as well.
Cold-formed steel joists with punched flanges facilitate the easy installation of long sprinkler runs and other utilities, including electrical and plumbing systems. Sprinklers are crucial in environments like warehouses, where the fire load is typically higher than in office spaces. The scale of sprinkler components is adjusted to meet the specific needs of each space.
Each sprinkler head is equipped with individual heat-sensitive valves that activate only in areas experiencing a fire. This targeted response reduces harm to occupants, minimizes damage to property, and effectively prevents the spread of fire beyond the initial room of origin.
To ensure optimal performance, it is vital to use certified materials and components. Always remove protective packaging from sprinkler heads before installation. Concealed sprinkler heads are also available for aesthetic purposes. However, proper spacing is critical; placing heads too close together can prevent adjacent sprinklers from discharging effectively, potentially leading to larger fires. Conversely, excessive spacing can compromise the system’s overall effectiveness.
Additionally, ventilation systems should be carefully planned to avoid interfering with the sprinklers’ operation, as excessive heat removal may prevent them from activating when needed.
Water Mist Systems
Water mist fire suppression systems use fine water droplets to control and extinguish fires by cooling the flames and displacing oxygen. These systems, which discharge water through specialized nozzles at high pressure, are effective in confined spaces and significantly reduce water usage compared to traditional sprinkler systems. This efficiency in water use results in less water damage and easier cleanup, making them ideal for environments like data centers and museums.
The main advantages of water mist systems include their environmental friendliness and reduced water damage. They use smaller pipes and components, requiring less space and making them suitable for retrofits where larger sprinkler systems might not fit. However, their effectiveness can be compromised in highly ventilated areas, where air movement can disperse the mist, reducing its fire-suppressing capabilities. Ensuring these systems are properly tested and certified is crucial for their performance and safety.
Water mist nozzle- designed to create a finer spray mist than conventional sprinkler heads.
Gaseous Suppression Systems
Gaseous fire suppression systems, also known as clean agent systems, use inert gases or chemical agents to extinguish fires. They work by displacing oxygen or inhibiting the chemical reaction of combustion, making them suitable for protecting sensitive equipment in data centers, telecommunication facilities, and museums. These systems leave no residue, minimizing cleanup and damage.
Their advantages include rapid fire suppression and safety for occupied spaces. However, they can be costly to install and maintain, and require sealed environments to ensure effectiveness. Proper design and regular maintenance are crucial for optimal performance.
Gaseous suppression- a costly system best suited for sensitive and high value electronics equipment.
Smoke and Fire Dampers
Smoke and fire dampers are critical safety devices installed in ductwork. They automatically close in response to heat or smoke, effectively shutting off airflow in HVAC systems. This function helps prevent the spread of fire and smoke throughout a building.
Fire dampers are typically required wherever air ducts penetrate walls with a fire-resistance rating of two hours or more. They are also necessary for all air transfer openings (non-ducted) in rated walls, regardless of their rating. Additionally, fire dampers are sometimes required at penetrations of rated floor assemblies and within shaft enclosures.
Fire damper designed to install in-line with ducting.
Final Considerations
Fire prevention in steel framing involves a comprehensive approach that includes the use of non-combustible materials, adherence to building codes, innovative products, and best practices in construction. By implementing these strategies, construction and design professionals can significantly reduce the risk of fire and ensure the safety and integrity of their buildings. Whether through the use of fire-resistant materials, effective compartmentalization, or active fire fighting systems, prioritizing fire safety in steel framing is a critical aspect of modern building design. To ensure maximum fire safety, it’s crucial to maintain and update fire prevention systems as needed, particularly as technology changes and the risk factors change due to evolving building usage.
Continuous Education
Ongoing training for installers, designers, and other construction professionals is essential. Proper knowledge and application of fire-safe construction practices can greatly enhance the effectiveness of fire prevention measures. Make sure to consult a qualified design professional to ensure that all fire safety measures in your project meet or exceed requirements.
Testing and Certification
Fire prevention and suppression systems need regular maintenance to ensure proper performance. System performance and layout should also be re-evaluated if and when the main activities and services of the building structure change.
Material and Component Selection
Choosing the right materials and components is critical. Many clips and connectors from industry-specific manufacturers such as ClarkDietrich and Simpson Strong-Tie are specifically designed to resist damage in the event of a fire. Selecting these high-quality, fire-resistant components can make a significant difference in the overall safety of the structure. Visit our clips store to see a wide variety of products that can improve the performance of your buildings.