When multifamily housing is constructed, each unit is required to be separate from adjoining units by an unbroken, ground-to-roof portion, or firewall. There are two methods of construction for these walls. Known as I-stud cavity systems, a hollow firewall offers the most space savings while maintaining a two-hour rating. The most common firewall is the H-stud system, a solid firewall offering less complicated assembly but requiring additional interior framing. In either wall, the purpose is to prevent fire from a single unit from spreading to adjacent dwellings. The I-stud system consists of one one-inch gypsum liner, two Type C gypsum wallboards (either 1/2-inch or 5/8-inch), and 1 1/2-inch acoustical battens, using a total space of four inches. The H-stud system consists of two one-inch gypsum liners, which allows for a more straightforward application. The total space required for this is 12 inches due to the additional interior framing involved.
Solid Type Area Separation Wall
The H-stud Area Separation Wall consists of 2" light gauge steel H-studs which secure two layers of 1" Fire Shield Shaftliner board between adjacent studs.
The H-studs are secured at the foundation floor by the flanges of H-stud Track. The same track is used back to back at intermediate floors to provide a splicing means so that the System can be erected one floor at a time. H-stud Track is also used at the roof line or at the parpet and at wall ends.
For a fire-rated assembly without the need for battens, a minimum 3/4" air space shall be maintained between the H-stud assembly and any adjacent framing members. When a 3/4" air space can not be maintained, the H-stud and H-stud Tracks are covered by screw-attached 6" wide battens fabricated from 1/2" Fire-Shield C Gypsum Wallboard; or 1/2" Fire-Shield C Gypsum Wallboards can be fastened to the H-studs and joints covered with tape and joint compound to provide a finished wall. Mineral wool or glass fiber can be installed in adjacent cavity shaftwalls to provide higher STC ratings.
At intermediate floors and at roof intersection, the steel framing members are attached on each side to adjacent structure framing with breakaway, heat softenable aluminum ASW Clips.
Area Separation Walls - I-Stud System
The I-Stud Area Separation Wall consists of 2 1/2" light-gauge I-Studs which secure 1" Fire-Shield Shaftliner board between adjacent studs having a 1 1/2" cavity which can be filled with glass fiber insulation to improve STC ratings. To each stud ilange, 1/2" Fire-Shield G Gypsum Wallboard is attached to provide the basic construction.
Resilient Fuming Channel can be attached to the flanges of cavity sides and the wallboard attached to it to provide higher STC ratings.
The I-Studs are held in place at the foundation floor by the flanges of light-gauge J Track. The same track is also used back-to-back at intermediate floors to provide a splicing means so that the System can be erected one floor at a time. Track is also used at the roof line or at the parapet and at the wall ends to cap off the construction, thereby providing a screw base for attachment of cladding and flashing clips, etc.
At intermediate floors and at the roof line, the I-Studs are attached to the framing of both adjacent structures with a breakaway, heat softenable aluminum ASW clip.