Choose between compression posts/rigid bracing and splay wires for seismic ceiling restraint

Steps

1. Confirm the ceiling is in a Seismic Design Category requiring horizontal restraint under ASTM E580 (SDC D, E, F, and the applicable elements of SDC C).
2. Understand the two accepted horizontal-restraint methods at compression-post locations: (a) four No. 12-gauge wires splayed 90 degrees apart from each other at a maximum 45-degree angle from horizontal, attached near the vertical strut/cross-tee intersection, or (b) rigid bracing used in lieu of splay wires, per E580.
3. Recognize the core engineering distinction driving the choice: rigid bracing can resist both compression and tension, while wire bracing can only resist tension — this is why rigid bracing is sometimes preferred in tighter plenum spaces or specific engineered conditions.
4. Confirm the required spacing/interval between restraint (compression post) locations across the ceiling field directly against the current adopted E580 edition or the engineer's seismic detail, since these intervals are prescriptive and have varied across editions.
5. Verify vertical compression struts are installed plumb and properly braced at the top connection — misalignment is a commonly flagged field deficiency.
6. Document which restraint method (splay wire vs. rigid bracing) was used at each location for inspection.