Fire Stopping

Fire stopping is the containment of fire or smoke through rated assemblies by the application of tested fire rated assemblies. There are 4 primary types of openings or joints associated with fire and smoke resistive rated assemblies, to which tested fire-stopping systems may be applied to prevent the spread of fire, smoke or gases:
  • Joints - Joints between fire-rated construction components (e.g. wall to wall, wall to floor, wall to ceiling)
  • Floor Perimeters - Slab edge / exterior wall cavity (curtain wall)
  • Penetrations - Openings containing mechanical, electrical, structural, security, communication, piping or wiring
  • Electrical boxes whose combined openings exceed 100 square inches in 100 square feet of wall
Fire-Stopping a Penetration
There are 5 important things to consider when deciding how to fire-stop a penetration.
  • What is the assembly you are penetrating made of (gypsum, wood, concrete)?
  • What is the item that is penetrating it (PVC, iron pipe, EMT, wiring)?
  • What is the annular space (minimum and maximum)?
  • What is the size of the opening?
  • What is the hourly rating of the assembly?
Fires topping is not synonymous with fire blocking.

Fire-Stopping Materials
  • "Intumescent" means that the material expands when exposed to fire or heat to fill a void in the penetration caused by the deformation or combustion of the penetration item.
  • "Elastomeric" products are flexible and prevent passage of heat and gases while permitting movement of the assembly.
There are several fire-stopping material manufacturers. Each manufacturer has their material tested and listed for specific applications. Not all materials are interchangeable with other "brands" or systems.

Some examples of materials or "components" found in tested and listed systems:
  • "Muffins"
  • Caulk
  • Flexible wraps
  • Mineral or Stone Wool
  • Putty
  • Spray