ADA Grab Bar Layout and Blocking Load
The accessible geometry fixture-clearance-check says it does not cover. 2010 ADA Standards: bars horizontal 33-36 in to the TOP of the gripping surface (609.4); side wall bar 42 in minimum, no more than 12 in from the rear wall; rear wall bar 36 in minimum reaching at least 12 in toward the side wall and 24 in toward the open side (604.5.1). The check people miss is that those two reaches have to fit ON the bar -- 12 + 24 is exactly 36, so any wider water closet needs a longer bar even though every individual dimension reads compliant. And 609.8 requires the bar AND ITS MOUNTING to sustain 250 lbf: a bar standing 1.5 in off the wall turns that pull into 375 in-lb of pry, 125 lb on the outer fastener at a 3 in flange spacing. Toggles do not carry it -- solid blocking, before the board goes up.
Formula and source
height ok when 33 <= bar height <= 36 in to the top of the gripping surface; side bar ok when length >= 42 in and distance from the rear wall <= 12 in; rear bar ok when length >= 36 in, reach toward the side wall >= 12 in, reach toward the open side >= 24 in, AND length >= the sum of the two reaches; prying moment = load x standoff; outer fastener force = prying moment / flange fastener spacing.
2010 ADA Standards for Accessible Design - 609.4 (position), 604.5.1 (side-wall and rear-wall grab bars at water closets), and 609.8 (grab bars and their mounting sustaining 250 lbf). The prying moment and fastener force are statics from the standoff and flange geometry, not code values.
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