How Do You build the floor in a Curbless Shower Stall?

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RogerPDX

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I have a concrete floor in my bathroom. There is a cutout in the concrete for the bath tub (it was never poured under the tub). I want to remove the tub and make it a curbless walk in shower area. There is sand under the tub.

I have some ideas how this might be done, but would like to hear from those who have done it, or know how it is done.

I can drill into the concrete floor (on each side of the sand pit) epoxy rebar stubs into the surrounding floor, then wire rebar onto the stubs, float in a new concrete shower floor, then tile it... But I wonder if that's all it takes to create a quality - no problem shower floor. Is it as simple as that? Do I need to include a membrane or is a good concrete (Jet Set) with a lot of rebar all that is needed?

Your comments are appreciated.
 

Jadnashua

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Code requires that a shower pan be waterproof...concrete doesn't cut it for that. There are lots of ways to make a reliable shower, but for a curbless design where you typically want to keep the overall height down so you can maintain the needed slope, a topical membrane is usually your best bet. Lots of companies make these, including Schluter, Noble, Laticrete, Mapei, Custom Building Products, and others.

Your biggest design issue is if you want to make the shower larger than the current tub's area. If you want it bigger, you need to then raise the existing floor outside of the tub area to maintain the minimum 1/4"/foot slope required. If the tub's area is adequate, it's easier. Keep in mind, every foot out from there, the floor of the rest of the bathroom needs to go up at least 1/4".

There are two classes of topical membranes: liquid applied and sheet membranes. Personally, while either can work, I prefer a sheet where you only worry about the seams, verses getting the painted on layers even within the required specifications without pinholes or runs.

Most of the manufacturers have a series of videos on their website that show you how their systems go together. But, bottom line, your shower does need waterproofing. How you best proceeded would depend somewhat on how thick your existing slab is. Also, keep in mind that the drain line on a shower is required to be at least 2" (this works for most showers unless you are planning a human car wash with LOTS of spray heads - it's a gpm issue). And, most codes require plumbing beneath the slab to be at least 2", so you may have that already, but if not, that could be an issue. Also, the drain line needs to also slope at least 1/4"/foot, so if you needed to move the drain (likely), that may play into it as well. The drain must also have a vent that, on a 2" pipe must come off of the trap arm within 5'.

Check out www.johnbridge.com .
 

Jadnashua

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Jim, thanks. Do you know which company makes the best, most fail proof system between Schluter, Noble, Laticrete, Mapei &Custom Building Products?
That's a loaded question...you'll find fervent believers in each system. Noble and Schluter have been in the business of sheet membranes the longest. Personally, I prefer Schluter's stuff, partly because it has less buildup for the required overlaps to obtain the needed waterproofing. But, some prefer the thicker membrane which may be more of an issue if used commercially where you have to worry about other tradesmen damaging your work before you get tile on top of it. Laticrete's sheet membrane has been around slightly over a year, and some find it easier to use than Schluter's. Schluter came out with theirs in the late 1980's, so it has been around a long time with lots of field experience.

But, for reference, check out some of Schluter's videos...the concept is the same for others you might choose. Some of it may be what is more easily available where you live. Be prepared for sticker shock when you price linear drains, though. They all are fairly expensive, and probably (not absolutely) what you want for a curbless shower. Your least expensive option on any brand is the tiled drain cover verses a pretty metal grate.
 
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