Designing Kitchens and Bathrooms - wheelechair accessable shower

I have stripped my bathroom which is 12 x 7 to the studs, as of right now there is a working toilet, I fixed any insulation, put up new vapor barier and am in the process of putting in the Hardiboard on the walls and floor. My question, I want to make the shower area 6x7' wheele chair accessible, is it possible to get the slope I need using just the hardiboard and morter but no mud or shower pan. I planned to use the schluter kerdi membrane as a waterproofer. The whole bathroom is open so the wheelechair has room to move with only a planned slight bump to access the shower area.

my floor is 3/4" plywood on studs of 14" centers, over the plywood is 1/4" plywood. I have stripped of old tile down to the wood

Schluter's Kerdi membrane can be installed over drywall. The special Kerdi shower drain is used. They also have the presloped shower pans. Go to http://www.schluter.com/8_1_kerdi.aspx to learn more and watch installation videos.

Thanks, I planned to use the kerdi drain but because the whole room is basically shower, I didn't want to use a shower pan if I could get away with it.

I was told by the people at rona that I can slope the floor 1/4" starting at the wall opposite to the shower opening going down to just the thin set at the drain then up again to the back of the shower wall. They gave panphlets on the Schluter's system and I have watched the video. They said to use the kerdi membrane over hardiboard and use the kerdi drain. They also told me I could use drywall screws to set the hardiboard, after reviewing other trends, I find they are wrong. Well, are they right or wrong? Can I build this shower without using a shower pan or ruber membrane ??? If I can, how do I set the drain in the hardiboard?

Some basics about kerdi. The best thing you can do is go to the Schluter website and read about kerdi. They have lots of good info and videos available that will give you most of the info your looking for.

Kerdi does not get used in conjuction with a pan liner. It is used in place of the pan liner. Its a complete water proofing system that covers the floor, goes over the curb and up the walls. You must use the kerdi drain as well. You still need a sloped pan, and that pan can either be a kerdi sloped shower tray (they make stock sizes) or you can make the slope out of deck mud if one of the stock sizes doesnt meet your needs. Hardibacker is not used under the kerdi on the shower floor, its either the kerdi trays or deck mud.

A traditional shower pan would have a deck mud preslope, a pvc pan liner and then a final med bed over the pan liner. With kerdi, the kerdi goes right over the preslope and then tile gets set to the kerdi, so you have only one mudbed (the preslope) instead of two.

Go to the Schluter website. Theres lots of great info there.

I have looked at the Kerdi system and will be using it, It looks like something I can do quite easily. I have a few questions though. I will be putting in the 60x32 with hole on center. The problem, my space is 57" x 32", can I cut the pan to fit?

also, I remeasured my joists, I am going to put 12" x 12" ceramic tile on my the bathroom floor. The subfloor is 1/2" plywood with 1/4 plywood on that. The joist is 2 x 9, I just measured it and had to check my measuring tape to make sure the first inch was there. There is a metal I-beam running the length of the house and cross supports every 6'. There is another bathroom almost directly underneath this one. The basement is finished in almost the same layout as the main floor.
My questions:

1) when I took out the tub I ended up with an area without the 1/4" plywood, I have a piece to put in, do I glue it before screwing it to the 1/2" plywood?

2)do I need more plywood on top of that or is the 1/2 " hardiboard enough?

You should be able to get away with cutting the pan 1 1/2" on each side.

The 1/4" plywood has to go. There is no 1/4" plywood that is an acceptable underlayment for tile. 1/4" plywood has delamination issues and is not suitable in a tile installation. If all you'll have left is the 1/2" plywood, then yes you'll need more plywood. At least another 1/2" of plywood, and thicker would be better. You don't need 1/2" hardi for the floors. 1/4" hardi is for floors, and 1/2" hardi is for walls. You can use the 1/2" on the floor but its not required and will do little to nothing to strengthen the floor. If you can add more height, always do that with more plywood. Make sure you read the installation instructions for hardi. It needs to be bedded in thinset. Follow the screw or nailing pattern on the board.

Is the cross supports every 6' that you are talking about just bridging or blocking between the joists? If so, it doesn't help with floor deflection. It sounds like your joists are 2" x 10" (actual 1 1/2" x 9 1/4"). What is the on center spacing of the joists, and how long is the span from the outer wall to the metal I-beam?

What is the on center spacing of the joists, and how long is the span from the outer wall to the metal I-beam?
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The on center is 16" and the span from the outer wall to the I beam is 12'

If your using ceramic tile your ok. If your using any kind of natural stone you have some work to do.

Since your using kerdi for the shower, you may also want to use ditra on the floor outside the shower. Remove the 1/4" underlayment and add 1/2" of exterior grade plywood, then ditra. If you dont want to go with ditra, add 1/4" hardi in its place.

I noticed before that you talked about 12" tile on the floor. I assumed that that was for the floor outside the shower. If thats not the case then we need to talk more about this.

I must have been reading your mind because I just cancelled my order of hardiboard and ordered 1/2 ply then am going down to home depot for the detra. I am using smaller 2x2 tiles in the shower area, I need non slip as much as possible. Another question, do I screw/nail and glue the new plywood to the 1/2 already there?

Make sure that the existing subfloor is fastened well to the joists. Use additional screws if necessary. Use just screws, no glue for the additional plywood.The plywood should be installed perpendicular to the floor joists. Make sure that you stagger the plywood seams so they do not line up with the subfloor plywood. Screw only into the plywood below, avoiding the joists as best you can. Screw every 8" in the field and every 6" around the edges of each sheet. Leave a 1/8" gap between plywood sheets for expansion. The ditra is a better choice. Good luck.

Thanks so much for your help. I am in the process of ripping out the 1/4" ply, will let you know how everything turns out. My husband really needs a shower!

Keep pluggin away. We'll do our best to help you out.

Johnny, I hate to jump in here, as ofcourse you've been right abaout everything you've been saying so far, but since this is still in the demo stage, may I suggest to sink the subfloor between the joists and then mud the whole thing. Easily get 1 1/4" of mud that can be sloped from every direction.

Just throwing that out there. Sloping thinset over a large area...I'd rather have root canal.

Hey Teds, do yourself a favor and forget about Hardi on the walls. Kerdi takes care of the waterproofing. The thinset layer for the Kerdi is so thin that the Hardi (the thirstiest of all cbu's) will suck the water right out of the thinset making it as fun to installt he Kerdi as catching flys with chop sticks. Regualr sheetrock is really all you need. Furthermore, if any of these walls are exterior walls, then you need to slice up the insulation facing with a utility knife so the inslation facing and the Kerdi don't create a double vapor barrier.

The achilies heel of and HC acc. bath is the toilet flange. Are you, or have you considered a wall mount toilet? The other option is to remove the flange and run your Kerdi all the way under the flange and then use Kerdi fix sealant under the perimeter of the flange before you set it. That way even the flange mounting screws are protected from water getting through.

.....back to your regularly scheduled tile advisor.

Now Heeeere's Johnny :)

Tilebri, you had me excited there until I read about the dreaded root canal. I did send back the hardi board and am using sheetrock. I am glad I decided to take a break and come here because I was just getting ready to put up the sheetrock on an outside wall. Sliceing up the insulation facing with a utility knife makes me want to cry as I just put up new facing, but I will slice it, don't want any problems in the future. I was told to use silicone around the toilet flange to protect it, I am using the ditra on the floor. How do I add the kirdi around it? Also, just picked up my tile, do I need to use movement joints. Opps, another also, I have ordered the ramp, does this go on top of the curb or instead of the curb?

Thanks