Shower remodel question

Hi there! My name is Ben and I need some help or reassurance with my Master Bath shower drain. The original shower was sunk into the concrete slab about 4-5 inches and the floor was built with deckmud and tiled over. After I got all that dug out, I found the builder had left an 16" opening in the concrete under the shower. I've raised up the shower area about 3 inches with concrete, but I've left the opening, by using a plastic bucket. I am running a thread over at John Bridge about this as well. I get the feeling that I should just fill up the bucketed area with concrete right up to and around the PVC pipe. I had some people tell me to leave a clearance around the drain to allow for movement. Which one is correct?

Thanks for the feedback.

Ben

The pan and the drain needs to be supported or the tile will crack.

The area was going to be backfilled with dirt/gravel, so I wasn't going to leave the pan and tile unsupported. That should have been included eariler, sorry about that.

Dirt settles; that is movement not support. Concrete hardens; it may crack, it may even drop down if the dirt and gravel under it are not solid....

How much will pipes move, in the future? Maybe 1/4" or 1/8", or perhaps some huge amount? If you leave a tiny gap around the pipes, you can fill that with soft foam.

People who build showers for a living can tell you more. Not me.

david

Thanks for the reply. So there isn't an issue with pouring concrete right up and around the PVC pipes then? If I wanted to leave a small gap, (i.e. less than an 1/8") what is the best way to provide the space? What do you do when building a new house?

Thanks for the answers,
Ben

You could wrap the pipe with some sill seal foam. Depending on when you install the actual drain, keep in mind that it goes over the outside of the pipe, so you can't have concrete right up to the pipe.

Have you looked at some of the more modern methods of installing a shower? Kerdi from www.schluter.com and Wedi from www.wedi.de both make some neat systems that are both fast, tileable, and neat. There are others as well. Nothing wrong with traditional methods, though, but the newer ones offer some distinct advantages. Depending on what you are doing, Kerdi is more flexible, but Wedi isn't far behind. They each come with some premade pans that can be cut to size (within limitations), but the Kerdi system can use a traditional mud preslope of any size. Check out www.johnbridge.com for some ideas and guideance on tiling, you won't be dissapointed.

The recessed area in the shower was there to allow the floor heights to be very close to the same inside and outside of the shower. Some people would kill to be able to do that, but you filled it in. Not a big deal, but it is a consideration. Probably the lowest buildup for a tileable floor from this point would be with the Kerdi or Wedi over a traditional preslope, liner, setting bed, if that is a factor for you.

Whatever you do, ensure you do install a sloped waterproof layer when you build your shower. Do NOT lay the waterproofing flat on the floor.

liquid membranes take up the least height -- just f.y.i. We have often read about liquid membranes on walls, where no extra cement product is addecd, just thinset for tiles. Liquid membranes go on floors too (a sloped floor, sloped in advance, pre-sloped if you will), right up to, over and into the drain. Then, thinset and tile. Very thin.

-david

Jim-
Found out about this great place over on the JB forums, tons of invaluable advice there! My original depression was about 6" down and it always felt like a long way to step down. I've been thinking about Kerdi, but for a house that I don't plan on being in forever, I think Kerdi may be more than I want to spend. It is a very tempting approach though. The top of the preslope might be just the height of the finished outside floor.

Do I need to wrap the outside of the pipe with sill foam or is that just an option? I was thinking about finalizing the drain height tonight. Here is picture of what I've got going on.

I left them out of the equation intentionally. During a discussion with the resident instructors at a recent class (these guys were neutral as opposed to the factory reps), it came up. None of the paint on membranes are full moisture barriers, either. They meet specs, but are more difficult to get done right. Get too much, and it is uneven and rubbery, get too little or leave a (microscopic) void, and you can have a leak. Judging you have the proper design thickness is much more difficult for the one-time user, and measuring it is not easily done without compromising the layer. Membranes, properly installed are much more forgiving. Testing of Kerdi shows that worst case moisture intrusion of a proper seam is 1/4", and they specify a minimum of 2". Some informal testing has shown that even a smaller overlap can work (not recommended). Take a square of the stuff, wrap it into a tight funnel and you can fill it with water and not have any water leak out the point even though you can see light through it! At the school, they have a carboard box that is sheathed with Kerdi they use as a cooler for drinks that sits full of water and ice all day...try that with a membrane, I don't think you'd like the results. Noble and others make some very capable membranes, so you have choices.

The Kerdi membrane is (if I remember properly) 40mils thick. Redgard, a paint on membrane is supposed to be applied the same thickness. The only difference is a thin layer of thinset, so this is a nit. Much easier to damage a paint on membrane in the process of building a shower than the membrane, in my opinion, too.