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duncanmorgan · Apr 22, 2008, 12:54 PM

Hello

I plan on building a tile shower on an concrete slab with drain already in place (there was an existing show in place) which sticks up about an inch from the slab (possibly there is a piece I can remove to bring the drain back down below slab level). The walls will be 2x4 stud and I'm planning on a wood curb consisting of 3 2x4.

I'm looking for basic steps on how to do this. I've found a number of how-to's online but none seem to refer specifically to building on the slab. I can understand that on a wood joist floor perhaps in the upper floor of a house, waterproofing via membrane is key but I'm not clear on the importance of that for an on slab tub.

So I have these questions

- is a concrete curb better than wood in this case?
- what type of drain set up would I use?
- do I need to pour a thin layer of concrete to slope the floor towards the drain?
- do I need duroc or other concrete all the way up or just one course (i.e. - 32" or whatever widths they come in)?
- would I use the waterproof wall board for the rest of the shower (i.e. - green drywall)?

Thanks
--Duncan

duncanmorgan · Apr 22, 2008, 12:58 PM

One further question - is it best to use concrete board or hardiebacker?

amricca · Apr 22, 2008, 02:16 PM

You could use a pre-fab shower pan, they come with their own drain set-up. Hardibacker is cement board and you should use that to the height of the tile as least, or all the way to the ceiling.

duncanmorgan · Apr 22, 2008, 02:22 PM

Thanks for the answer. I won't be using a pre-fab because I haven't had good luck with them in the past.

massplumber2008 · Apr 23, 2008, 04:36 PM

Hey DM:

If you are not going to use a prefab shower floor... (great idea AMRICCA... I forget these are out there sometimes)... then you will need to plan on using a membrane to create the shower pan... on concrete slab or on wood floor...same rules apply. Here, even though on concrete slab if water backs up in shower (for any reason) water can seep out the threshold or any place where the horizontal meets the vertical... understand..

For example, grout lines crack.. water will find the crack and it will seep down and eventually it will seek out where horizontal meets vertical (water is very good at finding these spots...especially AFTER you finish the job!!).

You will also need to plan on installing concrete board ON THE WALLS up to the ceiling (if tiling to ceiling) or to just a couple inches below where you plan the tile to end (then blueboard and plaster).

You cannot install hardibacker as a shower pan if you use a membrane for pan.... how will you secure it? Adhesive won't work here... screws through membrane won't work here... only a poured floor will work here.

Check out this link:

How to Build a Shower Pan

It breaks down the steps to install a new custom shower (with pictures... ;) ). These are a lot of work to do correctly... why many hire professionals to do. If follow all steps though, not really hard. Big issues occur when people cut corners... they are almost always disapointed!

Let us know what you think... let us know if need more information... Sorry I do not have better news!. Mark

PS...let some of the other remodelers onsite here chime in to confirm what I say...they will be along shortly

duncanmorgan · Apr 23, 2008, 04:45 PM

Thank you - good information.

duncanmorgan · Apr 23, 2008, 05:05 PM

So it looks like I can follow the instructions in this link almost exactly. I would pour a thin layer of concrete to slope to the drain (or perhaps not if the current cement slab already slopes to the drain, then hardiebacker on the sides nailed to the stud wall, the membrane which would glue to the hardiebacker and then float (no glue?) on the sloped concrete.

--Duncan

massplumber2008 · Apr 23, 2008, 06:02 PM

Hi Duncan:

You want to install membrane inches above finished floor/threshold, pour floor... THEN install the hardibacker (1/2" to 1" above poured floor).

Make it so membrane ends up behind hardibacker but you don't install screws so penetrate the membrane BELOW THE THRESHOLD... that make sense.. Here, if fold and seal all corners right and don't penetrate membrane below threshold with screws you have effectively created a sealed chamber that directs water and weep water to drain... period!

Which reminds me... use hardibacker screws (1-1/4") and construction adhesive on studs... AND when you see the drain for shower pan membrane there will be WEEP HOLES at drain. You must add small rocks/pebbles AROUND the drain so that concrete does not clog WEEP HOLES of drain. These weep holes and the sloped floor (under membrane) direct any residual water to drain --->>Increases life of pan!

Also.. why no prefab shower floors.. Prefabs are great... if set in modified thinset mortar or similar (reduces squeeks/movement inherent with prefab shower floors).

Let us know what you think... let us know if need more... Mark

*Still waiting for others to "chime in"... ;).

duncanmorgan · Apr 24, 2008, 08:02 AM

Thanks again Massplumber.

Three reasons I didn't consider a pre-fab are

a) because of the custom size required
b) we preferred the tile look
c) ones I've had in the past all have a springy feel and often end up leaking around the drain and I was constantly having to caulk.

Maybe I'll reconsider :)

--Duncan

ballengerb1 · Apr 24, 2008, 09:14 AM

Duncan, I'm jumping in a bit late here but just wanted to tell you about the prefabs. From what you describe the prefab was not installed correctly causing two of your problems. When the pan is put down on the floor it needs to be set into 10-20 globs of modified thinset or even joint compound. That stops the flexing and spongy feel and also leaks around the drain due to the flex. I have put down many Swanston pans and swear by them. Their drains will not leak due to a unique rubber collar friction fit, no glue no wrench. Building a shower pan from scratch is not an easy task for 1st time DIYer at building a pan. The chances of you having a leak the first time are way greater than a prefab. With a prefab you get tile on the wall where everyone looks and not of the floor and this is good, no grout to crack. Swanstone Single Threshold Shower Floor

massplumber2008 · Apr 24, 2008, 09:59 AM

Duncan...

Ballenger said it better than I could have! "Building a shower pan from scratch is not an easy task for 1st time DIYer at building a pan. The chances of you having a leak the first time are way greater than a prefab."

I agree 100%

Good luck... let us know what you decide... Mark

ballengerb1 · Apr 24, 2008, 10:33 AM

Just so we are clear Duncan, all 3 of us are talking about a prefab pan or floor. We are not suggesting the full unit which includes the walls. For the walls I'd do as amricca suggests and screw in cement board or , my preference, 1/2" Hardibacker and then install ceramic on the backer.