TinnerFlow™3rd YearSeismic / Brace LayoutYELLOW · Check First
A long duct run usually needs restraint for more than one direction. Check the seismic layout and add the missing brace direction by approved detail.
Side-to-side bracing alone does not control end-to-end movement. A long run can still telescope, swing, or pull joints if longitudinal restraint is missing.
Check the project seismic drawing/manual detail, brace spacing, run length, anchor substrate, and conflicts. Bring the foreman the missing direction before inspection.
Do not assume one brace direction controls every direction of earthquake movement.
Missing brace direction can fail inspection and let the whole duct run move in a seismic event.
Final direction still comes from approved drawings, specs, manufacturer instructions, employer policy, foreman/detailer direction, structural/seismic details, and AHJ/code requirements.