In priority order: (1) Grab bar blocking — 3/4″ plywood backer behind tile at toilet (33–36″) and shower (38–48″) per NKBA guidelines, rated for 250-lb load per ANSI A117.1 — costs $50–$150 during construction, $800–$2,500 as retrofit; (2) Curbless shower with linear drain — eliminates the most common bathroom trip hazard, enables walker or wheelchair access, floor sloped 1/4″/ft toward drain; (3) 60-inch turning radius — 60″ clear floor space for wheelchair 360° turn; (4) 36-inch clear doorway — minimum for wheelchair access; (5) Lever faucets and hardware — operable without grip or twist; (6) Comfort-height toilet at 17–19″ seat height — significantly easier to rise from; (7) Anti-scald thermostatic mixing valve (ASSE 1016) — prevents burns in users with reduced temperature sensitivity; (8) Slip-resistant flooring, DCOF ≥ 0.42 wet per ANSI A326.3.