Shower Drain Dilemma

[Yukoner777]

Way back at the beginning of my bathroom project, I raised the floor for my 4' x 4' tiled shower, in order to accommodate the proper slope for the drain and the trap. I bought the pre-sloped Kerdi shower pan with drain kit. Unfortunately for me, I didn't research the drain kit before building and it looks like the drain kit requires the top of the drain to be a minimum of 3 1/4" below the floor. As you can see from my pics, the top of the abs drainpipe is only 1 1/2" down from the top of the plywood floor.

At this point, I'm thinking I could add two sheets of 7/8" plywood to the shower floor. But with the combined thickness of the plywood and the shower pan, that would only leave me a little over half an inch height of my curb, so that would have to be raised, which in turn makes the step over the curb into the shower go from 6" high to about 8 or 9" high.

Are there any other drain options where I could still use the Kerdi shower pan? Or am I now faced with having to do a mortar bed shower pan and selling the Kerdi pan?

Other suggestions?

Thanks
Ross

 

[Christoff]

Is this shower in the basement or can you get at the plumbing underneath to change the height of the trap ?

 

[Sponsor]

 

[Yukoner777]

Is this shower in the basement or can you get at the plumbing underneath to change the height of the trap ?

No, I can’t adjust the height of the trap. The drain was originally installed 18” over from where it is now (I had a different design in mind for the bathroom when I built 15 years ago, and up until 1 ½ years ago, the bathroom was just roughed in). The shower is upstairs, but the trap is under 1 ½” of lightweight concrete (for the radiant floor heating). So I had to raise the shower base several inches to accommodate the drain line. I had to use a 90 degree elbow, 18” of sloped pipe, then another 90 degree elbow facing upwards, which is what is visible in the pic.

 

[Atomic1]

Regardless of the height problem, I dont see how you were planning on attaching the kerdi drain to an elbow. Isn't the flared end of the elbow too wide to accept the drain? If this isn't a problem, I think your only solution is to raise the subfloor elevation with additional layers of plywood.

 

[Jadnashua]

You don't have an ideal layout, that is for sure. That long length of pipe before the trap is just going to end up being a breeding ground for crud that will smell over time. There's a reason why they try to put the trap a short distance from the drain - the vertical height and short distance leaves less exposed pipe walls to collect soap scum and other crud. Having a significant step down from a shower is a problem. I ran into that personally in a shower in a small London hotel where they'd cobbled a shower into the space...almost did a face plant stepping out of the shower. Suppose, if you did it every day, you'd quickly learn, but with wet feet on tile, it will not be ideal. I highly suggest you plan for the installation of safety bar(s) to steady entry/exit from the shower.

If I remember, the bottom of the Kerdi drain is a hub, so while you could cut a short piece of pipe and essentially mate the bottom of the drain up against the top of the elbow, you'd still have the height of each hub to contend with. You might get away with cutting a small section of the hub away on either end (maybe the easiest way to do that would be with an inside pipe cutter), maybe totaling an inch overall, but it would not be to code. There should still be enough surface area to make a decent connection.

Schluter does suggest just using sheets of foam underneath their pan if you need to raise it rather than plywood (assuming the subfloor or structure is already strong enough. The weight of the pan and tile is enough...adding a couple layers of unneeded plywood IMHO, isn't a great idea. You'd use thinset between the layers to bond the foam sheets in place, just like when installing their foam pan. Rather than using the foam curb, you could build it out of 2x material, cover it in cbu or drywall, then finish it with the waterproof membrane (you can't install the membrane to wood - you need an approved sheet over it). Or, you could add on a short extension of your raised area, and put the curb on top of it.

 

[Reach4]

How about putting the drain over the trap? That would mean not using your pre-made base, or chopping it up. But it would seem to allow you to not need a shower platform.

Maybe there is a linear drain that would fit your needs.

 

[Jadnashua]

Linear drains are a nice (but pricey) option, but you need either a different drain and pan, or make your own. Keep in mind, though, that you'll likely be living with this for many years, and if it isn't 'right' now, it may bug you for a very long time, and doing it over will cost more than double.

 

[Yukoner777]

Thanks for the input guys.

A short piece of pipe will mate the elbow and the Kerdi drain - just long enough to fully insert into both.

If I have to flush that horizontal length once in a while, I'll do so. I agree it's not the best layout, but it's what I have to work with now. I may consider a small handrail - I'll see how it goes.

I don't see any problem with using extra layers of plywood to raise the floor. I'm planning on using some 2" strips of 3/4 plywood around the perimeter and two ribs in between. Then a full layer of 3/4" ply on top of that. The added weight would only be about 40 lbs.
I'll raise the curb using 2x material, then Kerdi membrane over that. Luckily I won't have too much tile to remove from the curb.

I'd considered before, having a non-centered drain, but it would have been right on the front edge which would have left me with a noticeably sloped baseline for the bottom tiles. In hindsight, I guess I could have used one of the linear drains. But at this point, that would be too much time and expense.

Thanks again for your suggestions. I'm sure it'll all work out. It's just some additional time - a drop in the bucket really in the big picture.

Cheers
Ross

 

[Jadnashua]

When using wood to build up your curb, you must cover it with a suitable backer material before you can put Kerdi over it...you can't put Kerdi directly onto wood. If you're going to place the foam curb on top of that platform, you can bond the foam with thinset, and Kerdi will bond fine to the foam.

 

[Yukoner777]

When using wood to build up your curb, you must cover it with a suitable backer material before you can put Kerdi over it...you can't put Kerdi directly onto wood. If you're going to place the foam curb on top of that platform, you can bond the foam with thinset, and Kerdi will bond fine to the foam.

Thanks for the reminder, Jim. I probably will use the foam curb.

 

[PorcelainVacation]

You don't have an ideal layout, that is for sure. That long length of pipe before the trap is just going to end up being a breeding ground for crud that will smell over time. There's a reason why they try to put the trap a short distance from the drain - the vertical height and short distance leaves less exposed pipe walls to collect soap scum and other crud.

While it isn't ideal, I have a bathtub that is plumbed this way and it has not been a problem. However, a bathtub probably scours the pipe better than a a shower because it drains a lot of water at once.

If I remember, the bottom of the Kerdi drain is a hub, so while you could cut a short piece of pipe and essentially mate the bottom of the drain up against the top of the elbow, you'd still have the height of each hub to contend with. You might get away with cutting a small section of the hub away on either end (maybe the easiest way to do that would be with an inside pipe cutter), maybe totaling an inch overall, but it would not be to code. There should still be enough surface area to make a decent connection.

How about swapping the elbow for a street El?