As to waterproofing the floor, I'd use Ditra on the entire floor outside the shower and Kerdi inside the shower.

If you don't want to do that, then use Kerdi in the shower (section A) and have it overlap the ditra in section B by a few inches for water tightness. I'd Ditra sections B and D at a minimum.

With curbless entries, I'm not a big fan of trench drains at the entry threshold. You can go with a central drain as you have depicted. Add grab bars and you'll be in fine shape.

If you really want a stable sure-footed platform, on two occasions I've built a center-drained, sloped shower floor, then used floor inserts to "level" the floor.

One was done with four slabs of stone that were set on feet to keep them level. The slabs were gapped about 1/4" so water could drain both between the slabs and between the slabs and the wall, then the water would flow down the sloped floor beneath and into the drain.

The second was done with a teak floor grid. I built it from teak strips and again, it was supported from beneath to keep it level. Water flowed through the gaps in the grid.

In both cases the showers were "roll-in" showers where the bath floor was the same height as the top of the stone or the top of the teak grid. Access with a wheelchair was very simple.

The teak grid was easily removable should the need ever arise. The stone slabs? A lot more difficult to remove and reset.

Mongo

Mongo, and anyone else who'd care to respond,

"I'd use Ditra on the entire floor outside the shower and Kerdi inside the shower."
Including the lavatory section? That is, the floor outside of A,B,C, and D?

"used floor inserts to "level" the floor."
Ooooooohhh. Very clever idea!

Thanks.
Keep those ideas comin'!

First off, take that NC publication and use in in place of toilet tissue. There's not a shower around that doesn't have compound pitches, if it's constructed properly. As for a trech drain and Kerdi, the two don't mix. Either you have Kerdi and use their conventional drain, or you have the trench drain with a CPE membrane. As for anything constructive to say about this, Mongo's already pretty much covered it, and then some.

Just keep in mind that the normal pitch in a shower isn't anywhere NEAR where it would need to be to cause someone to lose balance.

Bill,

Sometimes you are a REALLY funny, colorful kind of a guy. Toilet tissue, huh? I must admit, having just gone through the 'preslope' issue, I was wondering how you could accomplish a well-sloped shower without compound pitches, even if those pitches were 'ever so gentle'. But you weren't going to catch MOI saying that to those NC people, not I. :)

Mongo,
toadangel already gave you your accolades. I think I'm gonna add a teakwood floor grid to my curbless shower. You're allowed to come and build it, in your spare time, that is.

Bill,
Thanks for the info about NC paper. I'm restraining my comments.
Just shows to go ya about believing everything you read...

In regards to shower pitch. The plumbing codes state that the floor must pitch a minimum of 1/4" per foot but not more than 1/2" per foot.

The plumbing code also states that the threshold of the shower door must be a minimum of 2" higher than the finished elevation of the drain opening.

lazypup,
Thanks.
So if the drain is moved so that it is at least 4ft from the shower opening, the code is followed? Alternatively, a flexible threshold could be used (apparently, not a good idea though).
I'm not bringing up the NC diagram showing shower tile floor slope: 1/8" to 3/16" per foot. Nope, not me.

That's why this forum is so great. So many knowledgeable folks willing to share info.

Could she put a trench drain under that back banch in her diagram and slope the entire floor in that direction, and thus avoid both compound pitches and a threshold drain?

Take a look at this website: http://www.tuff-form.com/tuff_form.htm

I think these guys can help you, i saw this product at the kitchen and bath show, its a pre formed floor with a built in pitch. Its a product we are looking into for a couple of jobs we have coming up.

Here is a link that might be useful: Tuff-Form

I have built two curbless showers with in the past year and a half. Both where built using Ditra, Kerdi and Red Guard. I have been having more and more clients ask for trench style drains and have spend about 8 months researching these beauties.

Quick Drain USA has a nice channel (trench) drain with excellent tech help and a wonderful website. ACO now imports to North America from the UK and I have found that their drain can fit on top of a Schulter drain rough in (this can not be done without modifying the stock unit and I'm sure it will void any warranty).

All that said I should have much more answers to this specific question in roughly 3 months time.

The more I look at the trench drains and the more we explore the options it creates it's no wonder the channel drain is the hottest look of any new shower.

As far a a nice clean looking curbless shower with a simple Kerdi Drain the entire bathroom needs to be waterproofed. Toilets should not be placed too close to the shower entry because a typical floor mount toilet is the biggest weak link in a wetroom floor. A better option is installing a wall mount toilet or small covered curb (i.e. pony wall, glass block wall, frameless glass on low curb) that separates the toilet location from the wet zone.

Make sure you pipe your new curbless with at least a 2" drain line (with properly sized vent line) your design and polumbing package might need a 3" drain line so even though you want the new channel drain you may need to install a standard drain in addition to the floor drain.

It's hard to teach an old dog new tricks - Push your builder or tile guy to research harder. Be prepared for extra costs. Framing changes, concrete work and structural engineers may need to be used. I designed my last two around standard framing and raised the transition from the hallway to the bathroom to 3/4" - 1" (Solid hardwood reducer at doorway) and pitched everything back to a single Kerdi drain.