Doug's Shower Remodel - help

[Brian in San Diego]

Doug,

If you are using Hydroban or similar liquid surface applied membrane then you can use screws to attach hardiebacker. My question for you is what material is the curb made from? If you are using wood I would rethink that for a SOG installation. If you are going to use wood no matter what then make sure it isn't pressure treated.

Brian

[dawedler]

My question for you is what material is the curb made from?

I believe it is made of wood with some type of mortar covering. Not sure if it is pressure treated or not. It is part of the original shower. You can see a picture of it in post #7.
What does SOG mean again?

[Brian in San Diego]

Doug,

I wouldn't be putting hardie over that curb. It already appears to be suitable for tiling over. I would clean it up and then waterproof it with your Hydroban and call it done.

SOG is "slab on grade".

Brian

[dawedler]

I was hoping to raise the height of the curb a 1/2" to match the height I raised the knee wall top (with a piece of 1/2" hardi) so the existing door frame will fit. Anyway to raise the curb 1/2 an inch?

The old shower kneewall and curb did not have CBU on the top of it. It had a cultured marble sill attached directly to the top 2x4 of the knee wall and the top of the curb. I plan on tiling the top of the knee wall and curb with travertine.

[dawedler]

I wouldn't be putting hardie over that curb. It already appears to be suitable for tiling over. I would clean it up and then waterproof it with your Hydroban and call it done.

Is it OK to put a piece of Hardie on top of the curb and waterproof it with fabric and Hydroban? Or is this going to cause problems? (I am trying to raise the height a 1/2 inch so my shower door frame fits.) I am trying to understand what potential issues I might be causing by doing that.

[Houston Remodeler]

Without reading the entire post, I think you can hydroban the curb then add the 1/2" of cbu to the top of that. Attach it with a little thinset.

[Brian in San Diego]

By the letter of the law hardiebacker and all CBUs are supposed to be attached with screws. If you are sure there is wood under what appears to fat mud then you can certainly do that. (I would still put thinset under the hardiebacker.) We normally would advise against screwing into a curb, kneewall or any other horizontal surface in a shower but since you are waterproofing over that I would say you can do it if you like.

In kerdi installations one would screw pieces of drywall onto stacked 2x4s to make a curb and then kerdi over it. I believe you are essentially doing the same thing. Screws first, waterproofing second.

[dawedler]

normally would advise against screwing into a curb, kneewall or any other horizontal surface

Just curious, how then do you attach Hardie (or other CBU) to the top of the kneewall?

[dhagin]

Originally Posted by Doug

Just curious, how then do you attach Hardie (or other CBU) to the top of the kneewall?

Originally Posted by BSD

In kerdi installations one would screw pieces of drywall onto stacked 2x4s to make a curb and then kerdi over it. I believe you are essentially doing the same thing. Screws first, waterproofing second.

Essentially the same method for any other surface applied waterproofing, except many require CBU instead of drywall. Install any CBU according to manufacturers installation instructions, including the thinset under it.

[dawedler]

I am ready to tape and thin set my hardie walls. I have a few questions:

1. on the Hardie edges that meet the drywall do I use the thinset or drywall compound?

2. How flush (or countersunk) do the screws for the hardie walls need to be? Mine seem to have a slight edge of the head still exposed. I will be waterproofing the walls with Hydroban. Is this small ridge a problem?

3. How do I account for the difference in thickness of drywall and hardie?

4. Do I tape and thinset the corners then Hydorban or just use fabric membrane and Hydroban? Or should I use both tape/thinset and fabric with Hydroban?

5. how wide of a joint knife or taping knife should I use for the Hardie joints?

That's it for now.

[Houston Remodeler]

Doug,

1- If in the dry area, drywall mud is fine. If wet area, use thinset. If covering with hydroban, use thinset.

2- level or dimpled is optimal, but if you can barely feel it you are fine. Nothing over the thickness of an old dime though. The lumpier it is the harder it is to lay the tiles, particularly if you have tiny tiles.

3- float with thinset, float wth drywall mud, shim the hardi....

4- tape and thinset. No cloth needed with hydroban unless you feel the urge.

5- 6 inch is fine, but I like to use my 12" trowel... I am so old school

[dawedler]

Deck Mud Question:
I am ready to pour the deck mud. Is the sand-portland 5:1 mix ratio by weight or volume? (or does this make a difference?)

[cx]

Usually easier by volume, but you can do it either way and ain't nobody gonna notice.

I suggest you check the Shower Construction thread in our whirl-famous Liberry before you begin. Some helpful info in there.

My opinion; worth price charged.

[dawedler]

Thanks CX.
I've been to the Shower Construction thread several times. Very helpful.
I just wanted to confirm the mix before I mix it.

[dawedler]

I poured the deck mud for the shower floor. I think it turned out pretty well for a first timer. We'll see for sure when it cures.
How long does the deck mud need to cure before I put on the Hydroban?