Min. shower size

[Sifu]

In an R2 dwelling unit, when a shower is the only bathing fixture, ANSI and FHAG require 36"x36". I have a design, using the FHAG that has the following detail. I can find nothing in either guideline that allows this, other than some guidance on tolerances. ANSI includes that this is not permitted in the "design", but might be acceptable in "the field". So am I missing something?

 

[arwat23]

It looks like that's more a construction tolerance thing than a design thing. 36"x36" is minimum for design purposes. If the contractor builds this thing at 35.5"x35.5", then I guess that's within tolerance.

 

[Yikes]

In ADAS and CBC 11B-608.2.1, the shower dimension is exactly 36"x36", not minimum 36"x 36". The dimensions are exact because the intent is to be able to reach the grab bars and pull yourself form the wheelchair onto a transfer seat. A 72"x 72" shower (for example) would be too far to reach, so that's why the dimensions are listed as absolutes and not minimums.

Of course, based on another recent thread here, we know that absolute dimensions, and/or minimum dimensions with no stated maximum, are subject to manufacturing and construction tolerances (ADAS / 11B-104.1.1).

The Los Angeles Neutral Accessibility Consultant (NAC) contacted several fiberglass shower surround manufacturers and found out that the "vertical" shower walls are actually angled inward towards the base so that during manufacturing the one-piece shower can be successfully pulled off its mold.
The smallest taper they found had at least a 3/8" variance, and many were larger. The alternative is to site-build the shower walls, such as with tile, but even then each individual wall is subject to construction tolerances for both the framing and the tile work, resulting in a cumulative tolerance that is much greater than 3/8".

Therefore, there is a lot of manufacturing and construction tolerance that is considered acceptable for shower surrounds.

 

[Sifu]

I understand the construction tolerances in the field, and somewhat understand the language the standards use to make allowances for them. I guess I am puzzled by the specific language in the submittal to offer both a design size, and an actual size. I haven't seen it this way before and wondered about what seems to lower the bar for the minimum size. If the contractor and/or suppliers see 35 1/2" on the plan will the bar now be lowered so that 35 1/2" is the design, and tolerances creep down? ANSI says the tolerances are acceptable "in the field" but not in the "design". In other words, if upon inspection the shower is now 35" will the claim be that the loss of another 1/2" is due to construction tolerances in the field? I would rather see the design at 36" min. and leave it at that I guess.