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View Full Version : "Elevated" Shower Pan


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Joe D - Mon Nov 4 23:38:50 2002
I live in a high rise condo in downtown Chicago. I have already redone one bath and am starting in on the second. For the second bath, I'd like to try a mortarbed shower pan and have read a ton of material on the subject - I think I'm ready to give it a go. Hope the following makes sense -- My problem is that the p-trap for the old bath tub was set in the concrete floor of the bathroom (remember-its a high rise condo)and the top of tub drain was close (~1 1/2 inches) to the floor. I've dug out the old fittings from the top of the p-trap and cut a groove/channel in the floor to accept the new shower drain, which I plan on extending out to the middle of the new shower. The problem is that I can't get the top of the new clamping drain close than about 6" to the floor, due to the height of the drain / p trap etc. I'm thinking of building a "false floor" for the shower around the new drain by using 2x4's as "joists" laid on the concrete and then covering with 3/4" plywood. This should give me a flat shower "floor" at the level of the drain. From there, I will lay my sloped mortar bed floor and continue on with membrane, mortar bed, etc. I'm interested in opinions ( if you can figure out what I'm trying to describe!) as to whether this will work or not. I'm a little concerned that the floor of the shower will be 7" or so above the floor level, which will mean that my curb will be a 10" or so "hurdle" to get into the shower! Does this sound like it will work?? One more question - is the curb absolutely necessary, or, if the shower is sloped correctly (1/4" /foot)will a glass enclosure attached directly to the tiled floor (i.e, no curb)seal effectively?? Any and all thoughts are welcome. Thanks.

Bryan Klakamp - Tue Nov 5 00:35:05 2002
First a caution: Cutting into the concrete floor could possibly weaken it. Especially a groove. Before you go further with anything like that, a structural engineer should be consulted. Do you have room in front of the shower to extend the floor out about a foot? That would create a step outside the shower, and would then make the curb a reasonable height. Can you get to the area under the floor? If so, you could install a new trap under the floor/above the ceiling. Again, caution should be taken in cutting any new holes in the concrete floor. Hope these suggestions help.

Joe D - Tue Nov 5 01:06:55 2002
Bryan: Thanks for your ideas. The channel in the floor should not be a problem. The floors are 12" thick reinforced concrete, and my channel is only 1 1/2" deep (did not hit any rebar). The building engineer for the condo approved it before I started - this is fairly routinely done to run things like new electrical, etc. in the building. I don't have access to the p trap from below - its buried in the ceiling and interior wall of the unit below me. Anyway, I like your idea of creating a step, but I'm not sure I have the room for it. The entry door and toilet are too close to make this work, I think. I'll have to take a closer look at the layout. I'm really thinking of eliminating/minimizing the curb, but am wary of the potential for this to leak badly. I've seen this type of tiled shower base in bath showrooms, but I think this is more for show than practical use (not too many people take showers in showrooms - even in Chicago). Thanks again for your ideas.

Bud Cline - Tue Nov 5 17:52:49 2002
Joe, You might want to read up on your covenants before you go altering a floor in a high-rise condo. Sometimes very risky business. :)

John Bridge - Tue Nov 5 19:20:50 2002
Hi Joe, Welcome. :) Let me explain the right way to do this, and then if we can't do it, we'll find another "right" way. ;) When you move the shower drain, you need to move the trap with it. Otherwise, leave the drain where it is. Although it's not ideal, a shower floor can be built with the drain on the end. Questions: Is the existing trap in a block out in the floor, or is it encased in concrete? Could you put an S bend in the drain pipe (riser) to move is just slightly inward and still use the existing trap? Do you see where I'm headed? You wouldn't need you false floor, which by the way, I think would be an abortion. ;) P.S. The Swan company makes acrylic shower bases with the drains on the end. They are intended for this exact renovation. http://www.theswancorp.com/

Rob Z - Tue Nov 5 22:02:41 2002
Hi Joe What is the pipe and trap that is in the floor? PVC, ABS, Copper, Galvanized? I just pulled on of my PVC clamping drains out and measured 2 1/4" from the underside of the clamping portion of the drain to the bottom of the drain. A 2" x 1 1/2" flush bushing can be fitted inside the hub on the bottom side of this drain. If the trap is 1 1/2" down in the concrete, that would put the bottom of the clamping drain only 3/4" to 1" higher than it would normally be. Since the sub floor is a super sturdy 12" of concrete, the shower floor could even be thinner than the standard 2" of mortar that many of us use. The overall height of the shower floor may not be much higher than is done normally. If you have copper or galvanized pipe/trap, you could cut it out and use a Fernco connector to transition to PVC.

Joe D - Tue Nov 5 23:46:09 2002
Thanks for the replies! To answer a few of your questions: The P trap is 2" galvanized and was set in a plastic housing (maybe an old pail??) in the floor. The trap was then bushed down to 1 1/4" brass slip fitting for the original tub drain. The whole thing was then back filled filled with concrete. I've dug down to the P trap to get at the brass fitting, which after some blood sweat and tears came out nicely ( aided by a 3/4 drive socket with a 24" cheater on the end!). So now I've got the end of a good, reasonably clean 2" female P Trap looking up at me from ~3-4" below the floor. I'm not crazy about digging any further to clear the P trap. Rob - You're right in your measurement - but to get the drain out near the center of the shower I will need to stick a 1 1/2" street ell to the bottom of the clamping drain so I can run back to the trap... this is what raises the whole thing up. John - Beleive it or not, I was originally considering leaving the drain where it is, but after reading some of the material out there on mortarbed shower bases I figured it was best to center the drain. I think I can sneak the drain towards the center a bit - I'll have to look at it. I really don't want to dig that trap out and mess with it if I don't have to. The trap was under the very end of the old tub, which means I can't add a clamping drain directly above because it will almost be in the shower wall. Would an alternative be to sweat a copper drain to a bronze bushing in the galvanized trap fitting? I think I would pick up some clearance if I did this. Technically, I think I would need to use a dielectric coupling, which will blow the clearances all over again. I also was looking at the ready-made shower bases - someone makes one with a center drain with the whole thing elevated to allow for a horizontal pipe below, but I think it was fiberglass which I would like to avoid like the plague. Does anyone know how does Swanstone holds up?? I still am intrigued by the mortar bed method and am dying to give it a try. I agree the thing runs the risk of looking like an abortion. I spoke to a glass shower door enclosure installer who said I DEFINITELY need the curb, even if its only an inch high or so. He said he has had nothing but problems with "curbless" elevated bases leaking(are these type bases called "buttresses"??) Anyway, I appreciate the ideas - thanks for the help. By the way, this website is teriffic. Joe

John Bridge - Wed Nov 6 07:35:31 2002
Okay, you know what you're up against. One thing you need to know, though. The reason the trap goes directly under the drain is so that it can be cleaned out through the drain opening should it become clogged. Although it might be possible to run a snake through your street ell and then through another ell, into the trap and around the bottom and back up, I wouldn't want to have to go through that.

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