How to measure a shower seat
Lower a folding seat into its use position first. Then measure from the bathroom finish floor to the top of the seat. Section 610.3 requires a reading from 17 to 19 in.
Seat depth is taken from the seat wall. A rectangular seat keeps its rear edge within 2½ in. of that wall, with its front edge 15 to 16 in. out. Its side edge sits within 1½ in. of the adjacent wall.
An L-shaped seat uses the same main seat depths. The L portion has its rear edge within 1½ in. of the wall and its front edge 14 to 15 in. out. The end of the L lands 22 to 23 in. from the main seat wall.
Seat location and grab bars by shower type
Under 608.4, a transfer shower must have a seat, folding or not. Section 610.3 runs it from the back wall to a point within 3 in. of the compartment entry. Grab bars go across the control wall and along the back wall to a point 18 in. from the control wall.
Section 608.4 requires a folding seat in roll-in showers required in transient lodging guest rooms with mobility features. Where a standard roll-in shower has a seat, it must fold and mount on the side wall next to the controls. It runs from the back wall to within 3 in. of the entry, and 608.3.2 keeps grab bars off the wall above it.
In an alternate roll-in shower, the folding seat mounts on the front wall opposite the back wall. It extends from the adjacent side wall to within 3 in. of the entry. Grab bar height follows 609.4: 33 to 36 in. to the top of the gripping surface.
Installation mistakes that fail inspection
One error is lining the seat up with a nearby bench or toilet instead of checking the 17 to 19 in. band. Another is mounting a standard roll-in seat anywhere but the side wall next to the controls.
Grab bars placed above a standard roll-in shower seat conflict with 608.3.2, which also caps their distance from adjacent walls at 6 in. A rectangular seat whose front edge sits more than 16 in. from the seat wall misses 610.3.1.
Weak backing is harder to see. Section 610.4 applies the 250 pound force to the fastener, mounting device, and supporting structure, not only to the seat itself.
What to look for when buying a shower seat
Pick the seat shape for the compartment first. Then check the product drawing for front edge depth, side clearance, and the L dimensions.
Ask for load data showing a 250 pound vertical or horizontal force at any point without exceeding allowable stresses. For standard or alternate roll-in showers, 610.3 requires a folding type.
Confirm the seat length for your compartment before you order. It has to reach from the back wall, or from the side wall in an alternate roll-in shower, to within 3 in. of the entry.
