First bathroom renovation questions

[dataslayer]

I have this bathroom renovation project that I decided to take on by myself. Its been an on going project for 2 months now, and I have to say, I'm quite pleased with myself since this is my first renovation project. Everything looks good across the board, but I have a few questions before I lay down tile.

I put cement board in the tub surround (screwed directly into studs) and on the entire floor (mortared then screwed in). On the whole, its level, but in some places there are little dips. When does a dip become too big and it needs to be fixed? The biggest I've seen is 1/8". Just for reference, I'm going to be putting in 12"x12" ceramic tile in both tub and on floor, and using a 3/8"x1/4" square notched trowel.

Since its seems like this is always asked, my Deflecto is L / 434.

Also, I have a cast iron toilet flange that I didn't remove. Originally i thought i was going to have to, but as i put the cement board down, it seemed like it would work. But now i realized that the bottom of the flange is just a bit too low for the depth of the tile, so the tile won't fit underneath it. Is there something I can put under the flange, like a shim, that would make it secure when someone uses the throne?

One last one. When i installed the cement board in the tub, I couldn't put it over the lip of the tub, as it would have caused the board to bow. So instead I installed it with the board resting on the lip. Is there a way I can put a seal there where the board meets the tub? Once tile is installed, I will also be putting silicone in between the tile and tub.

Thanks in advanced!

[Shpedly]

As to the floor flatness, it depends on tile size and the size of grout joint your using. Heres a link that shows the different standards based on both. https://www.tile-assn.com/CMS/Images/85/86.pdf The general standard is 1/4'' over 10 foot span or 1/16 over 1 foot.

Not sure what you mean on the toilet flange. Tile should not go under flange, that I know of, just close to it. If the flange isnt high enough after tiling, there are spacer rings made just for this.

Not sure on the tub lip, but I'm sure somebody will be around shortly to address that. Sounds like you needed to fur out your studs some, an prolly wise to do if you can at this point.

[WendyHMN]

If your dips are small as you say, you can fill them with whatever thinset you're using to set the tiles.

Ideally, your closet flange will sit on top of your finished floor. My code (yours may be different) says you can either have it on top of the tile or on top of subfloor as long as it is securely fastened to the subfloor in either case. If you don't have room for tile under there, I wouldn't use a shim. I would custom cut a wood support that will fit under the flange and screw through it into your subfloor. Also, if the flange is low you'll need a fatter wax ring or a flange extender to avoid unpleasant leaks.

Furring out the studs for your tub surround is the way to go. Is this tub also a shower? If so, you'll need some kind of waterproofing either behind or on top of the cement board. Do you have something in mind?

[dataslayer]

Thanks for the replies.

I had a feeling that my dips weren't too bad and that the thinset would fill them in. Based on my grout size and the chart provided, I should be fine.

As for the toilet flange, creating a custom wood support is a great idea. The space between the cement board and flange is 1/4", the and the tile is 5/16" tall - just a shy too big.

As for a thicker wax ring, i figure the difference in the tile height set in thinset vs the toilet flange is 1/16". I think I will be fine with a normal size wax ring. But good point for me to look at once the tile is laid down.

Finally, the tub. It is used for tub and shower (the shower head is at about 78" off the ground). I had been going back and forth about some sort of membrane to go over/under the cement boards. I opted not to, only because two people in the family said it wasn't necessary - the construction worker and the engineer. But, as I said, I have been teetering.

Since the cement board is already screwed in and taped up, I'd rather not take it down and fur out the studs. I was reading on here about kerdi membrane over the cement board with kerdi fix caulk or something like that could bond the cement board to the tub. Is that true?

[Houston Remodeler]

construction worker and the engineer.

The tile pro's here will always recommend a waterproofing layer.

Yes Kerdi will be an excellent choice.

[dataslayer]

Thanks Paul.

What is this Kerdi-fix i keep reading about? is it a caulk that would help form a seal between the cement board and the tub?

[cx]

Kerdi Fix is not a caulk, John, it's an adhesive sealant made primarily for attaching Kerdi to Kerdi and other surfaces. Little spendy, but really useful stuff and sticks to a lot of surfaces that are important when building showers. I don't use it much, but I wouldn't start a Kerdi shower without a tube at hand.



Can order it from FloorLife, among other places, by clicking their square to the right side of your screen.

My opinion; worth price charged.

[dataslayer]

Thanks CX!

I'm really getting some good help in understanding some of this stuff

I'm still feeling unsure about the cement board at the top of the tub lip. Any good way I can bond the tub to the cement board? Would thinset work as the bond between the two, especially if i put the kerdi as the waterproofing membrane on?

[Brad Denny]

Hi John,
The Kerdi membrane, which covers the entire space to be tiled, can be affixed to the tub lip with Kerdi Fix, so you have essentially "bridged" over the tub/CBU joint with the membrane.

[Houston Remodeler]

When hanging the kerdi fabric on the walls;

1- put blue painters tape on the tub flange where the kerdi -fix will go. This keeps the dripping thinset from making it dirty and wet.

2- hang your kerdi fabric so it overlaps the tub 2 or 3 inches.

3- after the kerdi is installed (and allowed to cure if you have the time) peel away the blue tape.

4- apply a bead of kerdi-fix tot he tub flang

5- press the overlapping kerdi fabric into the kerdi fix

6- use a razor to trim off the excess kerdi fabric.

[dataslayer]

After a few posts, i feel much more comfortable about that gap. Add to that a better water proofing system than just cement board and tile. PHEW!

Since I don't have Kerdi yet, I don't know the installation instructions, but should assume I should thinset the Kerdi to the cement boards. I have flexbond left over from when I did the cement boards, but I can use durabond or versabond (is there any difference?) as alternatives.

Also, when installing the Kerdi, should i overlap two pieces or have them touch and then thinset between then?

Thanks you everyone for your help. This forum is a god-send to find for the DIYers...

[WendyHMN]

A good place to start is the Schluter website. There's a link to the right. From there you can download the shower system installation handbook and see some videos. For more useful information, you can get JB's kerdi shower ebook right on this site. Those sources will answer all the basic questions so you can start asking tougher ones.