Schluter Kerdi new shower, ton-o-questions

[Jeff_H]

I have a bunch of questions that I could not find answers to in various other posts.
I'm installing a 32x60 Schluter pan & Kerdi shower system into a pre-existing concrete floored bathroom that used to have a tub.

1. I had to rip out and rebuild one wall. I ripped out the dry wall & tile on the other two walls (3 wall shower). I painted the studs with Kiltz anti-bacteria primer, insulated, then installed Hardibacker directly over the studs (no 4 corners touch & I used the special screws). The wall doesn't seem to be very flat and I'm concerned about just applying thinset-kerdi-thinset over the hardibacker in hops of making up for any imperfections in flatness.

2. I've been told to use non modified thinset, "rapid dry" type. I'm installing marble 12x12 on the shower walls, and various size tile on the rest of the bathrooom. Can I use the same thinset throughout the room? Which brand is best?

3. Since I'm wanting to build in a small corner seat, can I ust cut that corner out of the Schluter pan, insert my seat, then kerdi over it all?

4. I was planning on building a shower sill using 2x4s coverd w/ kerdi, thinset, & tile. Any problems with this process?

5. Since I need to repostion the drain, I was going to knock out the needed concrete, repipe, then fill in with sand and top pff with Quickcrete, leaving the drain about 1inch above the floor level for the Schulter drain..does this sound right

6. I was told that I can just tile over my old old laminated countertops vs ripping it up and rebuilding it all. is this realy possible and workable????

7. (last one really!)I managed to knock off all the old tile and keep the original drywall relativly intact in the rest of the room. can I retile over that area or do I have to rip out the old drywall and replace it?


thanks for any help

Jeff :bang:

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[pfeener]

The pros will be along in a little bit, but I can get you started.

1. The walls must be flat before you install the kerdi. Remove the board you just installed and either plane down the framing or add furring strips to get it flat. Spend some time here; this will make your life a lot easier when you're setting tile. Make sure it's square as well as flat. When you install the Kerdi you have to press out all the excess thinset with a tool such as a 6 inch sheetrock knife, so any imperfections in the wall will just come through.

2. I used Versabond from Home Depot for both under and over the Kerdi. I lot of folks from the forum use it as well. Look at the date stamp before you buy it. Don't buy anything older than 6 months.

3. You'll have better luck if you build the bench inside the shower after you've applied the Kerdi. You might also check out "better bench" from innovis. I lot of people on the forum have used and recommended the product. I installed one in my shower and liked it.

4. No problem with this approach.

5. Sounds about right, but I'd measure it up after you get all the components. You don't want to be off. Why don't you leave it 5-6 inches above and cut it down after you get all your components and can measure it accurately.

6. Don't know

7. Unless you can get it flat, I would tear it out. It's going to be more trouble than it's worth.

[John Bridge]

Hi Jeff, Welcome aboard. :)

The curb would need to be covered with either drywall or cement board before applying the Kerdi.

Look at the drain. Make sure you leave enough room under the tray for the funnel part of the drain.

Get your framing straight, square and plumb. There's no sense starting out with a screwed up base. :)

[Jeff_H]

I knew using screws vs. nails would come in handy. At least I havn't gotton all the backer board on yet, so it's not a huge deal.

thanks!!

[bsakrieger]

Greetings,

I just can't stop coming back to this forum. I am also in the midst of a 32x60 schluter - kerdi installation, mine is over wood subfloor. I read in your post that you applied Hardibacker to the walls. Not sure why, since you don't need to use it with the kerdi membrane, but no big deal there. My main point is to be careful when applying cement backer board directly to the wall studs. I had a total gut and remodel in my other bathroom years ago, and my buddy who is a Gen Contractor who does lots of this type of work suggested that I use sheetrock behind the cbo. This was to add a layer of support to the cbo, since it can yield when people lean on the wall while in the shower/bath. More likely - if someone slips and braces themselves against the wall, the point load if between studs may cause movement and a crack in grout or tile.

Not sure how likely this is, but I did use sheetrock with 1/2" cbo over it in a bathtub and tile installation. I used 30# felt between the two sheets for moisture control. The walls are 'rock solid' (bad pun) and it all worked very well. Perhaps it was overkill, but I will let the experts weigh in here if they are still viewing this thread.

Barrett - near S.F.

[Jeff_H]

Thanks Barrett
The Hardi board was baught and installed as a prelude to a regular (non kerdi)installation. I found out about the kerdi after I had put up some of the backer board already. Normally, from what I've seen, gypsum board is installed over bare studs with only insulation inbetween the studs. Gypsum is no stronger lateraly then concete baord(as far as I know), unless the papar provides tension strength to the board?

I figured, I have it, might as well use it. Besides, I know it will never rot like drywall will.
I guess if I was really worried about lateral (tension) strength of the board I would put a layer of OSB under it, but that would change my dimensions and I really have little room for change.
The Hardibacker is 1/2 inch, so it's fairly stout. - not too worried about punching through it.

[bsakrieger]

Jeff,

I understand what you are saying, especially when you already have a plan. As I said, I'm not sure how likely it is to happen. I think my buddy (the general contractor) was basically saying that with the two layers, it's stronger than one. Sheetrock is pretty cheap, so that's what I used per his recommendation. Some of the really experienced experts here may have better information or history regarding such.

I had to do quite a bit of work to prepare for the schluter high dollar styrofoam pre-slope. I used it for two reasons -
1) my subfloor is 1 1/8 T&G plywood on 4x6 beams (joists). One of them ,of course, ran directly under the middle of the new shower. I didn't want to rip out the post and pillar supporting the beam entirely to accomodate a poured mortar pre-slope. So, I shaved it and added some parallel 2x6's to stiffen the shower floor. That gave me enough room for the schluter kit to fit flush to the adjoining original floor, thus giving me a barrier free shower.
2) I liked the 'system' as a package concept, especially the kerdi membrane and square drain.

You said you plan on backfilling after excavating with sand, then concrete. Perhaps base rock or similar would be better? What would be under the sand - leftover concrete, dirt under the slab? Again, John and the others would be best to get some answers from here..... good luck.

Barrett

[pfeener]

Just a quick note; you may already know this, but Hardibacker tends to wick a lot of moisture out of the thinset. You should wet it down before applying the kerdi.

[John Bridge]

Well, don't quite wet it down. Dampen it thoroughly, though. Don't have water running off it. :)

[Jeff_H]

I'm aware of concrete's wicking and since I bought an extra gallan of Kiltz primer, I figured I'd just use it on the backerboard to avoid the wicking problem. I called the both the Kiltz & Hardiebacker people, both agreed it was a good idea, but then that's factory people talking and not installers. So, if anyone has a reason not to use the primer on the backerboard, please let me know.


thanks

[jdm]

Jeff --

I don't think you want to prime the Hardi. While too much absorption can weaken the thinset, some absorption actually helps the thinset bond to the substrate. Porcelain is harder to bond to than regular ceramic because it absorbs so little water.