ADA: Water control and proper slope of curbless shower or wet room shower.

Universal/accessible design of the home from an occupational therapy and a construction perspective. This blog is part of a quest for cool, convenient, functional design that makes life safer, easier, and as maintenance-free as possible. It's about the lifestyle.


We install quite a few curbless showers. Most of the showers we install are tile, but we do install pre-fab showers as well. I like the prefab showers when the person has hard water because it is easier to clean the prefab showers then it is to clean the grout in the tile showers.

Prefab showers are usually less expensive than the tile showers. It is important to have a competent plumber/carpenter install a prefab shower to ensure they get the supports under the shower correct so that the slope of the shower floor is appropriate and water doesn't pool.

One thing I have found with every curbless shower is that water tends to get all over the bathroom floor. I research curbless showers online, in hotels, in homes, anywhere I can find a curbless shower. I look closely at the design and ask loads of questions, without fail if there is no curb there is water on the bathroom floor.

The water on the bathroom floor seems to be due to either the shower curtains not being able to contain all of the water or just because drains don't seem to drain fast enough. We always use heavy duty shower curtains with magnetic lower edges which does reduce water outside the shower, they are expensive $100 but safety is important.

Of course the deeper the shower the less water gets on the floor. Shower depths usually range from 30"-60". I don't recommend installing a shower less than 36" because of water issues.

I like the 'hump' for the curbless showers because it does help contain the water. It is best for the hump be about an inch high with a 1:12 slope. (As an OT I find that the 1:12 slope is not usually an issue for wheelchair propulsion unless the person has severe upper extremity weakness.)

Another way to contain the water is to install a trench drain across the opening of the shower, but this isn't always possible because of the floor depth they require. At the very least when we install a roll in shower we usually also install a drain on the outside of the shower as well as the inside of the shower to help control the water that inevitably seems to get on the bathroom floor.

There are also collapsible thresholds for curbless showers which are rubber dams basically that collapse when a wheelchair rolls over them. These do a good job and I must admit I'm a bit surprised they seem to last for several years. Sometimes they don't seal well on the corners where the floor meets the wall so we ALWAYS caulk on the corners.

The slope of the shower floor should be 1/8"-3/16" per foot. Since water is always an issue the entire bathroom floor should have a waterproof membrane to prevent water damage since as we all know grout is not waterproof. We always run the waterproof membrane a few inches up the wall around the entire bathroom to prevent water damage around the base of the walls as well.

I could write all day about curbless showers. I hope this helps and I would love to hear others experiences, tricks, etc. for curbless showers. A great resource to answer all your questions on curbless showers is at


Anonymous said...

I would recommend quartzlock 2 urethane grout which is indeed waterproof and flexible. Also slope on a shower floor should always be 1/4" inch per foot, and NEVER more than 1/2" per foot, which usually rules out a level perimiter unless the shower is square, and the drain is in the middle. I would recommend an infinity trough drain along the back wall. It is very important when using the topical waterproof membrane like hydroban to always use the same manufacturers fabric around corners, because this IS where leaks happen.

Karen Koch said...

Thanks for the great information, you obviously have great expertise in this area.