Firestopping: Frequently Asked Questions

The International Building Code (IBC) first adopted a requirement for the special inspection of firestopping and fire resistance joint assemblies in certain buildings with the 2012 Edition. Since its adoption, we have performed third party fire stop and fire resistant joint inspections on over 1 Million square feet of space on accordance with ASTM E 2393 and ASTM E 2174. Below are some of the frequently asked questions we hear when serving in this capacity.

Jurisdictions such as Rhode Island and Connecticut have already adopted this requirement and it will be applicable in Massachusetts when the 9th Edition of the Building Code is adopted January 1, 2018.

Where does the requirement apply?

The new requirement will apply to high-rise buildings and to buildings assigned a risk category of III or IV per Section 1604.5 of the IBC. This table includes occupancies such as large assembly with occupant loads in excess of 300, educational occupancies with occupant loads over 250, most hospitals, jails/prisons, buildings with Group H, High Hazard Occupancies, and facilities housing emergency responders, among others. The requirement applies to any joint (i.e. head of wall intersection with floor construction), through penetration or membrane penetration of fire resistance rated walls, floors, and ceilings as specified on the project construction documents.

Where is firestopping required?

  • Through Penetrations: Breaches in both sides of a floor, floor-ceiling or wall assembly to accommodate an item passing through the breaches.
  • Membrane Penetrations: Breaches in one side of a floor ceiling, roof-ceiling or wall assembly to accommodate an item installed into or passing through the breach.
  • Joints and Perimeter Barriers: Openings in or between adjacent assemblies that is created due to building tolerances, or is designed to allow independent movement of the building in any plane caused by thermal, seismic, wind or any other loading (i.e. head of wall assemblies, curtain wall/slab edge joints

What test standards govern approved firestop systems?

The table below outlines the required test standard particular to each firestopping application:

Each of these test standards outline fire test methods effective in determining the performance of firestop systems subject to fire exposure governed by a standard time-temperature test and hose stream test. The time-temperature curve utilized mirrors that utilized for determining the hourly rating for walls and floors (ASTM E119).

How do I know if I am installing the right firestopping prior to inspection?

The code calls for the use of listed firestopping assemblies. It’s easy to get these confused with listed firestop products. A firestopping product is just one of the components in a listed firestopping assembly. The wall or floor assembly being penetration, penetrating item itself, annular space around the penetration, the manner in which the penetrating item is configured through the opening, etc.. are all part of the listed firestop assembly. For an arrangement to be considered a listed firestop assembly, it is required to be installed in the same manner in which it was tested. This information is readily available from the firestopping product manufacturer’s or from approved testing laboratories such as Underwriters Laboratories (UL).

What is the difference between a “F Rating” and “T Rating”?

F-Rating, or Flame Rating, is the period of time in hours the tested assembly remains in place without allowing the passage of fire during exposure or water during the hose stream test following exposure. T-Rating, or Temperature Rating, indicates the time in hours it took for the temperature on the unexposed side of the assembly to reach 325°F above ambient.

In order to obtain a T Rating, an F Rating must be obtained prior. Exposed penetrations through floors and fire resistance rated joints require a T Rating whereas membrane and through wall penetrations are only required to obtain an F rating.

Do membrane penetrations by electrical boxes need to be firestopped?

Membrane penetrations by electrical boxes may not require a firestopping assembly if they (1) have been tested for use in a fire resistance rated assembly and are installed per their listing or (2) they meet all of the following conditions (IBC 2012 714.3.1):

  • The electrical box area does not exceed 16 square inches;
  • The aggregate area of openings through membrane does not exceed 100 square inches in any 100 square feet of wall area;
  • The annular space between the wall membrane and the box does not exceed 1/8”; and
  • If located on opposite sides of the wall, electrical boxes are separated by 24 inches in different stud cavities.

If these conditions are not satisfied, additional insulation, fireblocking, or listed firestop assemblies arranged per Section 714.3.1 need to be added to achieve compliance with the code.