Minimum bathtub size?

[Yikes]

Is there a minimum size, or indeed ANY dimensional requirements, for bathtubs in ADA, or CBC 11B, or CBC 11A?

I had always assumed it was 30" x 60", but when I look in the code books all I see are requirements for the adjacent clearance next to the tubs, for the grab bar locations, for control locations, and for the height of a removable seat.

If that is true than it is theoretically possible to have an tub that meets all of the code requirements for accessibility and has the following features, for example:
- 27" x 27" clear footprint inside
- a 36" tall rim / step over height
as long as I have the required grab bars, removable seat inside, controls located properly, and clearances (in this case, 27"x 48") in front of the tub.

Not that I would actually want a tub like that! But I just want to know if you think there's actual code requirements for the tub itself.

 

[ADAguy]

A real "Rubik's" cube eh?

It depends, what isn't specific is what it may be, eh?

note: 36" tall "is not" step over height.
Consider the height of a prone body x2 (+ 3" freeboard) ='s how much water it will displace ='s minimum depth

 

[Yikes]

A real "Rubik's" cube eh?

It depends, what isn't specific is what it may be, eh?

note: 36" tall "is not" step over height.
Consider the height of a prone body x2 (+ 3" freeboard) ='s how much water it will displace ='s minimum depth

ADA Guy, I agree that a 36" soak tub is not really accessible unless you jump into the tub.

And the accessible removable seat would be about 18" below the rim.
And there's nothing that presumes a body must be prone in a tub.
And that's exactly my point: that the accessibility code does not appear to describe what IS an accessible dimension for a tub.
I doubt it's a "woops, we forgot to provide dimensions" moment, because the code authors certainly went into great detail for roll-in showers - - so why not for bathtubs?

Taking it even further: suppose for a moment I had a 32"x32" shower, with a 4" high curb: not accessible, right?
But what if I call it a (4" high) "tub" instead, and provide all the handrails, controls, and a removable seat, and 48" clear in front of this "tub". Now it complies with the letter of the law, right?

 

[SCBO1]

Now it complies with the letter of the law, right?

I don't think so...not unless that glass behind it's safety glazing!

Joey, have you ever seen a grown man naked?

 

[ADAguy]

4" would be a foot bath (smiling)

 

[Yikes]

I don't think so...not unless that glass behind it's safety glazing!

Joey, have you ever seen a grown man naked?

FYI, the picture is not my code hypothetical that I wanted you to respond to, I just grabbed something off the internet to show you that people actually do make unusual shaped tubs.

 

[Francis Vineyard]

Would the minimum bathtub dimensions be determined by the grab bars? If available could be smaller than the shower for grab bars 24 inches long.
It's height would be determined by the minimum and maximum above the floor and rim above the tub.
The minimum height of approximately 19 inches or a maximum of 24?

 

[Yikes]

Code for bathtub requires one grab bar to be at 33-36" above tub floor, and the other to be 8" above tub rim - -but it does not specify rim height, whether a conventional 12-19" or an unconventional 4", or 36" or 100" or whatever.
Bar length is specified as 24" minimum on the control end wall and the side wall, and 12" minimum on the back wall., so you know that wall has to be at least 24" wide, but that doesn't tell you how wide or long or deep the 'pool' of the tub itself has to be - - it only tells you about the walls above the tub, and in theory you could make the tub 24"x24" and it would work.

FYI, UPC 408.6 says that shower (bases) must have a minimum size of 1024 square inches and be big enough for a 30" circle, but it is silent on tub dimensions.

Please, someone prove me wrong!

 

[HForester]

Bathtubs are required to comply with standards. IPC Section 407.1. Manufacturers working to those standards are going to have model lines that will cover certain sizes (that are common to the industry). If the proposed tub doesn't comply with one of those standards, then it is an alternative approval situation (Section 105.2). ICC A117.1-2009 Section 610.2 indicates that the top of a permanent seat (at the head end of the bathtub) must be 17 to 19 inches above finished floor. If it is a portable seat (in other words, there is not a seat area at the head end of the bathtub), 15 to 16 inches above the finished floor.

 

[ICE]

Fatboy should weigh in.

 

[steveray]

We have held the rim height to 19" for better or worse....If you are transferring to a 19" seat, how are you doing that over a 24" rim....

 

[Francis Vineyard]

The OP asked where the code specifies minimum bathtub dimensions? For example what of a triangular shape tub in corner; do we determine the size from the allowable grab bar locations and clearances in reference to the bathtub?

Furthermore does the code specify bathtub rim height or just the seat height?

610.2 Bathtub seats. The height of bathtub seats shall be 17 inches minimum and 19 inches maximum above the bathroom floor, measured to the top of the seat. Removable in-tub seats shall be 15 inches minimum and 16 inches maximum in depth. Removable in-tub seats shall be capable of secure placement. Permanent seats shall be 15 inches minimum in depth and shall extend from the back wall to or beyond the outer edge of the bathtub. Permanent seats shall be positioned at the head end of the bathtub.

105.4 Figures. Unless specifically stated, figures included herein are provided for informational purposes only and are not considered part of the standard.

 

[Mr. Inspector]

Had a tub in the middle of the room with no grab bars in a nursing home so the care takers could get around the tub to help wash the patient. Made them go to the appeals board.

 

[ADAguy]

As with many manufacturers, their references to ADA are often misleading. Their compliance considerations typically contain disclaimers indicating "only if installed to ADA requirements".
ADA is not a product approval agency, it remains for the design professional to make a defensable argument.
As to rim height, it depends on the method and means of transfer, if self transfer a lower rim height is best but if using a transfer device such as a lift than height is less of a barrier.

 

[Yikes]

HForester and Francis Vineyard: The code specifies seat height relative to the tub floor, NOT relative to the tub rim.
In fact, the more I read it, the more the code seems conspicuous in its absence of dimensions for the tubs themselves.

steveray, I understand the practical issues of tub transfer height, and to be honest, 99.999% of my clients want a conventional bathtub. But the purpose of this post is to show that those practical limitations are not actually baked into the accessibility codes.

HForester, I tried to find a (freebie) online copy of the IPC or UPC referenced standards. In the California Plumbing Code, based on the UPC, it basically references ASME A112.19.1 or the CSA equivalent. I couldn't find it, but my guess is that it has to do with waterproofing materials, not actual tub sizes.
In any case, the main point is that ADA and CBC are notably silent on the issue of tub sizes.

 

[ADAguy]

Tubs, like the folks that use them, coming in many sizes and shapes. Doesn't form (and size) follow function in the case of tubs?

 

[Yikes]

Tubs, like the folks that use them, coming in many sizes and shapes. Doesn't form (and size) follow function in the case of tubs?

Showers also come in many shapes and sizes, and yet the code prescribes a minimum shower size... so why is it silent on a minimum accessible tub size?

 

[Paul Sweet]

Don't rock the boat, or they might come up with a size that nobody makes!

ADA (and ANSI A117.7, etc.) actually prescribes 2 shower sizes, and no deviation is allowed from the required 36" x 36" for a transfer shower.

 

[ADAguy]

Minimum tub sizes were established by manufacturers concensus back at the turn of the last century. Unlike showers which tend to be builtins.

Showers tend to be more accommodating to users, taking up less space without need of a vessel. They are actually more sanitary than tubs due to constant flushing of our surfaces.
Don't rock the boat, watch which you are inquiring about.

 

[Yikes]

OK, so I take it from everyone's answers that I am correct. There is no minimum size.
I won't rock the boat, but if I find a convention of CASp inspectors, I may win a few barroom bets.

 

[HForester]

Concerning Yikes' post, Monday at 5:37 PM: "The code specifies seat height relative to the tub floor, NOT relative to the tub rim"

No, relative to the floor outside of the tub. As previously provided...A117.1 says:

610.2 Bathtub seats. The height of bathtub seats shall be 17 inches minimum and 19 inches maximum above the bathroom floor, measured to the top of the seat.

This arrangement doesn't get it done correctly:

 

[Yikes]

HForester, you are correct, it is 17-19" above bathroom finish floor, not the bathtub floor.
That still doesn't prohibit a very tall or very short rim of bathtub.

 

[ADAguy]

It also depends on what you are transferring from: walker, WC, cane, etc.
To avoid tripping you should be transferring from the same height to the same height.
That being so, it would seem that the tub floor and the bathroom floor should be at the same height,
exclusive of the rim height. Lowest rim height would be best but then it wouldn't be a tub, would it?
Tubs being meant for immersion what would the minimum rim height be to accommodate this?

 

[Yikes]

There is no minimum rim height recommended for immersion. It can so small that only a child would get immersed:

There is no code requirement that the floor of the tub is the same height at the bathroom finish floor. Think of a sunken tub:

don't worry, I'm not purposefully trying to sabotage accessibility. I will use conventional 30x60 tubs that are visually similar in scale to what is shown in the code book. My only point is that it feels like a giant "loophole" in the code, except that it's so conspicuous that I believe the omission of dimensions was intentional, not an oversight.