Tile Flooring

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Posted by: from Ottawa
1/20/2013 at 12:21:02 AM

Trying to figure out what I need for my bathroom floor. I have ripped everything out down to the floor that sits on the joists. This floor is 5/8" OSB.

I want to put in a 40" x 40" curbless shower so I've thought that I would drop the floor in the shower area to being level with the top of the joists so 5/8" lower than the rest of the bathroom.

If I use say a Kerdi drain in the center of this shower, by the time it is installed the top of the drain is 1 3/8" above this lowered floor. Now slope up from there at 1/4" per foot for roughly 2 feet and that takes the top of the tile at the boundaries of the shower to 1 7/8" OR 1 1/4" above the bathroom floor OSB.

First problem that arises is that my bathroom is off of my bedroom which has 3/4" hardwood and that would mean 1/2" difference in finished floor heights. I assume that the 1/2" would be a tripping hazard and that I'd have to build / install a small transitional ramp at the bathroom entrance. Correct? And that is an option.

Secondly, I'll be using most likely 1/4" tiles on the floor, and installing floor heating as well. What I'm looking at is 3/8" plywood underlayment +1/8" in-floor heat mat + 1/8" Ditra+ 1/8" thinset + 1/4" tile which gives be a total height above the OSB of 1".

So I have shower exit at 1.25", bathroom at 1" and bedroom at 0.75". I can easily raise the bathroom floor to match the shower exit by changing the underlayment plywood thickness but that still means a 1/2" tripping hazard at the entrance to the bathroom. Alternatively, lower the drain a bit more. This may be an option depending on location of the joists and if the drain line can drop any further or is there some other options out there to help get the floors level?

Any suggestions or help with this would be appreciated.



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Date/Time1/20/2013 at 3:52:35 AM

Hello Ed,

The first thing I would do is replace the OSB with 5/8 or even 3/4 plywood so you can eventually skip the additional 3/8" plywood underlayment.

To drop the shower area is a good idea, however you cannot just cut/notch the joists, you have to ask a structural engineer whether you can do this resp. how you have to do this.

The Schluter system is not bad however in your case there is a better systems available. Please have a look at the WEDI Shower Systems: It is also possible to use the Wedi System together with a Schluter drain. This is what I mostly do to keep my curbless Showers as low as possible. The outer floor should be also a bit sloped towards the shower drain.

In some cases it is impossible (or too expensive) to avoid a little step in the doorway however there are a couple transition profiles from Schluter available which can take a bit of this step away. Furthermore you can ramp up the doorsill a bit. Anyway having a little step in the door is in my opinion better than having a curb in the shower.

Here you'll find some pictures and videos following a curbless shower project through its various stages from beginning to finished product.!/oa/6551238/ I have more pictures from a couple other curbless showers I built, however I didn't have the time yet to upload them.

3D-Tile-Design - Bertram Tasch

Maple Ridge, BC (Greater Vancouver)

(778) 886-9503

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Date/Time1/20/2013 at 8:08:57 AM

Fist thing I'm trying to figure out is why would you want a curbless shower. As you stated, there is existing 5/8's osb that will be meeting up to the shower base. Any moisture that runs into this area, will cause the osb to swell.

Now what you are trying to do can be done, but with an open shower the whole floor should be water proofed, at least up to 8ft passed the shower.

After you made you shower base form, you could install the pad, then a metal lath over and around the pad, and fill the base with a mortar level to the desiered hight to match up with the other flooring. Should not be wood. Either floor tile or vynal, and extra attation should be put into the area where both flooring materials meet.

Or just hire a tile pro.

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Dolphin Construction Co. in Ottawa
Date/Time1/20/2013 at 10:40:38 AM

I cud not read through your e-mail and your ideas suck big time. Hire someone who knows what they doing and do not touch anything yourself.

Good luck with your project, really I mean it.

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Date/Time1/20/2013 at 11:38:09 AM


I would hire a floring company. Simply because you may have weight issues that would require sufficient support and the transition issue can easily be addressed. An experienced flooring contractor can do it properly and, in the long run, probably do a better job and dollar-wise it may be the best route to go.

You sound like you've done the math, good on you, but there is also physics and general esthectics involved to do a proper ... up to code, job.

Regards from the west.


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Ed in Ottawa
Date/Time1/22/2013 at 11:32:44 AM


Thanks for your help. Yes a step at the bathroom entrance is definitely a trade-off over having a curb and is my preferred option.

I am not going the cut down or into the joist route at all. Most I'll do is lower the floor down 5/8" and maybe a bit lower right at the drain if that could help with keeping the finished shower edge height lower.

I will be replacing all the flooring with new be that 5/8" or 3/4" or whatever thus my questions on height approximations. Do my numbers seem to make sense to you?


Yes I understand the potential problem with the mortar and will deal with that. Also, I am not doing an open shower; there will be glass walls and door similar to photo below.

To all,

Of course I would take on a pro to do this if I think it would help. Concerning the weight issue, the old bathroom had marble tile all over it and from what I can tell I meet the l / 720 deflection requirements. So not concerned about that part of the bathroom. The shower and tub area may have to be upgraded a bit but once I finalize the design I will know but I'm just adding a shower and tub to what was already there.

Tile Flooring

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