Method of Building and Installation of an Interstitial Seismic Resistant Support for an Acoustic Ceiling Grid

A method of making and installing a suspension system for supporting a ceiling grid in a horizontal grid plane over a room and resisting vertical and seismic forces comprising:

• selecting tracks to be positioned in a horizontal support plane spaced above the grid plane, said respective tracks to be supported from a first wall and a second wall that is not perpendicular to and is spaced a distance apart from the first wall;
• selecting seismic joists of a length to extend between the tracks when mounted to the respective first wall and second wall;
• selecting a plurality of hangers for the seismic joists, each of which comprises a metal hanger bracket rigidly affixed to a downwardly projecting vertical rigid lever arm that is connectable to the ceiling grid and wherein the rigid lever arm is of a length sufficient to, when the seismic joists are positioned in the support plane, position the ceiling grid in the grid plane;
• configuring and sizing the seismic joists and hangers to, when installed, position the grid in the grid plane;
• at a construction site, mounting the tracks in the support plane to the respective wall first wall and second wall;
• interposing the seismic joists between the tracks;
• fastening the seismic joists to the tracks;
• positioning the respective hangers on the respective seismic joists;
• and
• fastening the respective hangers to the respective seismic joists.

A method of pre-fabricating a collection of parts assembleable into a suspension system for supporting a ceiling grid in a horizontal grid plane over a room and resisting vertical and seismic forces comprising:

• selecting tracks to be positioned in a horizontal support plane spaced above the grid plane, said tracks to be supported from a first wall and a second wall that is not perpendicular to and is spaced a distance apart from the first wall;
• selecting seismic joists of a length to extend between the tracks when mounted to the respective first wall and second wall;
• selecting a plurality of hangers, each of which comprises a metal hanger bracket rigidly affixable to a downwardly projecting vertical rigid lever arm that is connectable to the ceiling grid and wherein the rigid lever arm is of a length sufficient to, when the joists are positioned in the support plane, position the ceiling grid in the grid plane;
• configuring and sizing the seismic joists and hangers with a configuration to, when installed, position the grid in the grid plane.

A method for building a structure to support a ceiling grid and resist vertical and seismic forces comprising:

• installing a first track comprising an elongated channel, with a back face and an open channel front face forming a nesting cavity, by mounting the first track to a first wall by attachment to a plurality of wall studs of said first wall, such that the back face is against the first wall and the open channel front face is facing away from the first wall;
• installing a second track comprising an elongated channel, with a back face and an open channel front face forming a nesting cavity, by mounting the second track to a second wall that is parallel to and spaced a distance apart from said first wall, by attachment to a plurality of wall studs of said second wall such that the back face is against the second wall and the open channel front face is facing away from the second wall;
• wherein the first track and the second track are each mounted at substantially the same height;
• installing a plurality of seismic joists, each of said plurality of joists comprising a tubular steel beam with a height, a top, a bottom, a first end and a second end;
• wherein upon installation, each of the plurality of seismic joists is mounted between and generally perpendicular to the first track and second track such that the first end of each of the plurality of seismic joists is mounted in the nesting cavity of the first track and the second end of each of the seismic joists is mounted in the nesting cavity of the second track, such that each of the plurality of seismic joists is rigidly affixed to said first track and said second track, and is generally perpendicular to and generally spans the distance between the first wall and the second wall;
• installing on a plurality of seismic joists at least one seismic hanger comprising:
• a rigid lever arm;
• a bracket mounted on an upper extremity of said rigid lever arm such that said rigid lever arm projects downwardly from said bracket;
• said bracket comprising a top flange and a bottom flange, wherein said top flange and said bottom flange form a front nesting face, said front nesting face having a height, wherein the height of the front nesting face is substantially the same as the height of each of the plurality of seismic joists;
• and
• wherein the seismic hanger is rigidly mounted on at least one of the plurality of seismic joists such that the top flange is affixed to the top of the respective seismic joist and the bottom flange is affixed to the bottom of the respective seismic joist.