Determine when 2-inch wall angle and positive perimeter attachment are required on a seismic ceiling

Steps

1. Confirm the ceiling's Seismic Design Category first — the enhanced perimeter attachment requirements apply specifically to SDC D, E, and F ceilings under ASTM E580.
2. Confirm that the perimeter supporting closure angle or channel must be not less than 2.0 inches (50mm) wide unless qualified manufacturer's perimeter supporting clips are used instead.
3. Confirm the closure angle/channel is screwed or otherwise positively attached to wall studs or other supporting structure (not just resting in place), per E580's perimeter attachment requirement for SDC D-F.
4. If using manufacturer's perimeter clips as an alternative to full 2-inch wall angle, confirm this allowance is recognized by the code cycle referenced on the project — ASCE 7-16 Section 13.5.6.2.2 permits qualified clips as an alternative, but confirm which standard/edition the project actually cites before relying on that allowance.
5. If clips are used, confirm they are attached with a minimum of two screws per clip and installed around the entire ceiling perimeter, not just at select locations.