Because all three are installed to prevent the passage of fire and heat, it’s not a stretch to say that a fireblock, a draftstop and a firestop system each serve a similar purpose in a building’s fire protection. It is also the case that while one can use a handful of similar materials-some insulation products come to mind-to accomplish all three installations, most firestop materials aren’t installed as fireblocking or draftstopping, and vice versa.
The easiest way to differentiate among the three installations is to remember that you generally fireblock a partition, draftstop an open area, and install a firestop system in a penetration. A fireblock is a building material that is used to resist the passage of flame in a concealed interior space within a building. It is installed to cut off vertical and horizontal draft openings or to prevent fire and heat from moving horizontally or vertically through a building. The most common point of installation of a fireblock is within a partition at the edge of a floor when the studs by-pass the floor framing. A common example of a fireblock installation is one where the fireblocking material is placed at the floor line between the shaftliner panels and the adjacent trusses or joists in a gypsum area separation fire wall system.
DraftstoppingSimilar to fireblocking, draftstopping is installed to prevent the movement of air within open building areas and is most often installed in crawl spaces, attics and floor assemblies. Multi-unit housing projects are often draftstopped at specific intervals to prevent fire from jumping between adjacent units via a common attic space. If the area above the occupied space in a garden apartment complex is not draftstopped, a fire breaking though the ceiling of a top-floor apartment could move laterally through the common attic space and spread to adjacent occupied units.
A firestopping system is comprised of materials or products that are designed to resist the passage of heat and flame through a penetration in an assembly. The International Building Code identifies two different types of firestopping applications: a membrane-protection firestop system and a through-penetration firestop system. Firestopping generally involves the use of a specific method of protection that is compatible with the fire-resistance characteristics of the system being penetrated. In many instances, firestopping materials must be tested as a part of a system in accordance with a specific third-party testing protocol.
Section 717 of the 2009 IBC identifies specific requirements for the installation of fireblocking. Installation is limited to combustible construction-think Type V wood-frame construction-and material must be installed at floor-to-floor transition points and horizontally at 10 foot intervals. In addition, other specific construction elements, including stair stringers, double walls, wooden floor sleeper systems and transfer areas between horizontal and vertical spaces, must be fireblocked. The code contains a long list of acceptable fireblocking materials, including gypsum board, batt, blanket and loose-fill insulation, wood structural panels and particle board.
IBC Section 717 also quantifies draftstop requirements for subdividing concealed space in both sprinklered and unsprinklered buildings. It defines specific requirements for the location of draftstopping and identifies the materials that may be installed as draftstopping. As an example, unsprinklered Type R-2 buildings-a motel or an apartment building-with three or more dwelling units generally must be draftstopped within floors and in attics with materials that are installed in line with the dwelling unit or sleeping unit separation walls. Buildings constructed for other use groups are most often subdivided based on area requirements.
Functional but Not GlamorousFireblocking and draftstopping materials need not be fancy or attractive; they simply must cut off the flow of air through a concealed space. Scraps of lumber, plywood, and gypsum board are commonly used as fireblocking and draftstopping, and something as simple as strips of 1/2-inch-thick drywall fastened to the side of floor framing members and tight to the top of the ceiling membrane will typically suffice. You actually can install a door in an attic draftstop as long as the door has an automatic latch and a self-closing device.
Firestopping requirements appear primarily in Section 713 of the IBC in the prescriptive provisions for penetrations. Interestingly, the IBC doesn’t contain a definition of the word firestop; instead, it incorporates the word into definitions that explain the various types of firestop systems.
Similar to the code philosophy for fire-rated assemblies where the code defines the test method and then permits the user to determine the appropriate system to install to comply, the IBC generally does not list materials that are permitted to be used in a firestopping system. Some exceptions exist for grout materials used to seal penetrations and specific products employed to seal electrical outlets; however, in general, a firestopping material or system must be tested in accordance with a specific test method and then installed to comply with the tested system.
Because firestopping systems occasionally must withstand seismic or building structural movements, they tend to be more complex than fireblocking or draftstopping systems. Often, firestopping systems incorporate both fixed-in-place and flexible materials and many have the ability to “float” as a building or a partition moves. A firestop system typically has at least one component that either expands when exposed to heat or exudes moisture when exposed to heat. In so doing, the system seals or protects the penetration and prevents heat and flame from passing through a rated assembly.
While all three concepts can be overlooked in the construction of a building, each should be incorporated as an element of an overall plan to ensure building occupant safety. The installation of small pieces of scrap material can prevent the vertical spread of fire and heat and save lives in an occupied structure.