In most commercial buildings expansion joints are a fact of life. These joints are necessary to accommodate expected building movements due to thermal changes, wind sway and differential movement typically caused by seismic events. When these joints occur in a fire-rated floor or wall a product or system must be used that has been rated to that same level. This means if the joint occurs in a 2-hour rated floor assembly the expansion joint system used to fill the joint must also be rated for 2 hours. Per current building codes, these joint assemblies must be tested at an accredited testing agency such as Underwriters Laboratories or Intertek and be tested in accordance with ASTM E-1966 or UL 2079 test standards.
There are three typical ways these joints are fire-rated:
- Pre-compressed seals with an integrated intumescent coating are the industry’s newest way to provide this rating. These systems are used for joints that are 6 inches or less and provide up to 50% movement in compression and extension. These seals can be used in either a horizontal or vertical application, either exposed or behind a metal cover plate. This system has the added benefit of providing a watertight seal and has a silicone face that can be colored to match the desired aesthetic of the project.
- Fire barrier systems that use a draped or compressed ceramic fiber blanket product are another way to provide a fire rating. The draped systems can handle joints up to 32 inches with large range of motion capabilities. These systems can be used in horizontal or vertical application and usually need a metal cover plate to achieve their rating.
- The third way to provide a fire-rated system is the use of a rated mineral wool product that is compressed into the joint and covered with a sealant. These types of joints are usually used in smaller joints of 4 inches or less with a limited range of motion. You will find these most often used in floor assemblies.