Appropriate shower curb on concrete floor

[stardog]

I will soon be re-doing a small standup shower. I will be installing a new preslope, liner, and top bed, as well as installing new backerboard. When it comes to the curb, I am still unsure how to approach this. The house is built on a concrete slab, so I am not sure the best method for constructing the curb. I know most construction uses a triple layer of 2x4's to build the curb to an appropriate height, but someone advised it is best not to use a wood curb on a concrete floor.

Considering my situation what is the best practice for building a curb on top of a concrete floor? And how would it be attached to the floor? Tks for any advice.

 

[Jadnashua]

You have a few choices, but one of them is probably not wood!
- use bricks or concrete pavers - you can use thinset to build it up
- use one of the foam curbs
- use a product like KerdiBoard from www.schluter.com

All three of those can be bonded to the slab with thinset.

Maybe a bigger question is what method are you planning on using to build the shower? My preference is to use a bonded membrane which ends up with fewer steps, and, probably the biggest thing, makes the entire shower waterproof verses only the pan, and the rest water resistant.

There are lots of ways to successfully build a shower, but it is a very detail oriented procedure, and skipping or messing up one step can be the cause of failure. It's not all that hard, technically, but it does take some skill. you need to figure out what method, since some of them will require a special drain. I suggest you check out www.johnbridge.com for help on deciding on your shower technique, but ask here about installing/fixing the plumbing to include the drain and valves.

 

[Sponsor]

 

[stardog]

You have a few choices, but one of them is probably not wood!
- use bricks or concrete pavers - you can use thinset to build it up
- use one of the foam curbs
- use a product like KerdiBoard from www.schluter.com

All three of those can be bonded to the slab with thinset.

Maybe a bigger question is what method are you planning on using to build the shower? My preference is to use a bonded membrane which ends up with fewer steps, and, probably the biggest thing, makes the entire shower waterproof verses only the pan, and the rest water resistant.

There are lots of ways to successfully build a shower, but it is a very detail oriented procedure, and skipping or messing up one step can be the cause of failure. It's not all that hard, technically, but it does take some skill. you need to figure out what method, since some of them will require a special drain. I suggest you check out www.johnbridge.com for help on deciding on your shower technique, but ask here about installing/fixing the plumbing to include the drain and valves.

 

[stardog]

Thanks for the quick response. Wasn't sure whether thinset would secure everything properly together, although I had read about others using it. So I guess that's what I will do. Once the pan elements are in place and everything is leakproof I will be installing Durock or similar with a coat or two of Redguard to seal it up.

The only plumbing need will be to find a plumber to change the current two handle faucet with a single handle unit, plus raise the shower head a few inches from where it is currently is. Of course I say that with the assumption I not run into any problems whatsoever.

 

[Jadnashua]

If you want to use RedGard, carefully read their shower waterproofing instructions. Also, you'll want to pick up a wet film thickness gauge and learn how to properly use it. Waterproofing the walls without tying it into the pan's waterproofing can lead to trapping moisture behind things. A properly done surface waterproofing system tends to use waterproofing on top of everything, but then also requires a special drain.

You should not need, not will it work properly if you treat thinset like say brick mortar...it is designed to actually be THIN.

 

[stardog]

Thanks for the tip. Appreciate all your help.

 

[Jadnashua]

While there are thinsets that are designed to be used thicker, a typical thinset is designed for a maximum installed thickness of about 3/16" (that's not the notch size, but how thick things are after setting the tile in place). What happens if you make it thicker is that it shrinks and cracks, and if a modified thinset with a latex base that needs to dry (some chemically change like say an acrylic modifier), it can take forever to properly dry out and can be spongy for a very long time. The cement in it, OTOH, will cure, become crystallized, and potentially shatter (microscopically) because of that excessive movement. It only works properly when installed as designed.

Good luck on your project. A conventional, liner-based shower will work fine if installed properly, but as I said, I prefer the more modern (if 30-years history is still considered modern!) bonded membrane shower. In that case, you're dealing with getting the seams done right, because the whole sheet otherwise is waterproof. Can't say the same with a liquid waterproofing system...works fine if you have very good workmanship, but it's too easy to get a pinhole, thin layers, thick layers, and maybe runs and drips. When not done well, it can fail (well, that's true with any install, but more common with a liquid one than a sheet IMHO).

 

[Jrland]

Hello. I've been researching brick curbs and from what I gather is to use a layer of thinset to bond brick to a concrete slab and then to use brick mortar for the construction. When using Kerdi, the curb could be waterproofed with the shower pan. To be clear, would I use a layer of thinset and install the first layer of brick to that or would i use a layer of thinset and then apply a layer of brick mortar before setting the brick? Thanks so much. I appreciate the help! Have a great day!

 

[Dj2]

I'd do a concrete curb. I form it, put rebar inside the form, then pour concrete, let it dry a few days and then finish it.
I would not use any wood at all.
I once did a total bathroom renovation and the curb contained wood. When I removed the curb, the wood was completely destroyed.