NOOB questions.

[briano96]

I'm planning on remodeling my rather small second floor bathroom. I've pulled up the old linoleum floor tiles and 3/4" plywood which had roofing felt on top of it. What I have left is 3/4" tongue and groove planking. There were tons of nails securing the plywood to the planking. The planking is in good shape, very solid.
Questions:
1. Should I screw the planking down to reduce deflection of the subfloor or is nailing okay?
2. I was thinking of using Ditra and Kerdi-Band in order to make a waterproof floor. Will I be able to apply the Ditra directly onto the planking or is some kind of backerboard required?
3. Or perhaps there is a better and/or easier method??? I am open to any and all suggestions as this is my first tile job. TIA.

[ddmoit]

Welcome to the forum, Brian.

1. Should I screw the planking down to reduce deflection of the subfloor or is nailing okay?

If any of it is loose, I would use screws to tighten it.

2. I was thinking of using Ditra and Kerdi-Band in order to make a waterproof floor. Will I be able to apply the Ditra directly onto the planking or is some kind of backerboard required?

Before you put Ditra or a backerboard down, you will need at least a 3/8" of suitable plywood - 1/2" would be even better. Most folks don't feel the need to waterproof their floors, but Ditra with Kerdi-band would indeed be waterproof.

[John Bridge]

Welcome aboard, Brian.

You'll need plywood over the planking. The least you can get by with is 3/8, and 1/2 is better. Then the Ditra or 1/4 in. cement backer board. Yes, you can screw or nail the planks to the joists, but nail or screw the plywood into the planks only, not the joists.

[briano96]

Thanks for the lightnin fast replies Men! I forgot to mention that the closet flange (toilet) is set to the height of the T&G planking. Whoever put down the 3/4" plywood cutout the footprint of the toilet from the plywood so that it was set on the planking while the linoleum tile was set up on the plywood. In other words the toilet was recessed into the floor????

I was also thinking of using Ditra because of how thin it is since I was concerned about setting the toilet on a "low" closet flange. I think I'll be able to solve that issue with a "Stack & Seal Flange Retainer Ring" which allows you to raise the height of the flange. The floor doesn't have to be waterproof but Ditra doesn't seem to be very expensive and it sounds easier than making a mudbed.

Just to be sure I've got it straight here's what I've got:
1.screw t&g planking into joists.
2.nail or screw 1/2" plywood into planking (not into joists).
3.apply Ditra to plywood using modified thinset.
4.use unmodified thinset to set tiles on the Ditra.

BTW, this job is gonna include tiling the walls and shower so I will probably be back with more very BASIC questions.

[briano96]

Oh, BTW John, I ordered "Tile Your World" from Amazon the other day. I'm looking forward to getting my hands on it. Thanks.

Brian O

[ddmoit]

I think you've got it, Brian.

Make sure the new plywood runs perpendicular to the joists.

Now that you have this thread going, bookmark it and come right back here with any additional questions on this project.

[briano96]

Thanks Dan. I see your a Bears fan, me too. Born, raised, and still live in Chicago. Wait till next year!!!!

[briano96]

Well I've removed the old 4"x4" wall tiles and patched and skim-coated the drywall. I've got 1/2" plywood to install on the 3/4" T&G subfloor on top of which I'll install Ditra and then the ceramic tile.

I've cut the plywood to fit the room, including cutting out a hole for the toilet flange. I've got a gap of about 3/8" to 1/2" between the plywood edges and the walls. Should I have cut the plywood so it was a "snug fit"? Can/should I fill the gaps with silicone, mortar, jif-set, grout?

[cx]

Welcome, Brian.

You want to leave the gap around the perimeter of your subflooring. What you have is more than you need, but it's fine as is.

Originally Posted by Brian

Well I've removed the old 4"x4" wall tiles and patched and skim-coated the drywall.

Hope that's in a dry area of your bathroom.

My opinion; worth price charged.

[gardner]

gap of about 3/8" to 1/2" between the plywood edges and the walls

Personally I've been trying for around 1/4 around the edge, but I wouldn't tear it out and start over because of that.

fill the gaps

In my recent project I used foam backer rod (intended for insulation) and it seemed to work fine.

[briano96]

"Hope that's in a dry area of your bathroom."

Yeah CX, the drywall that won't be covered by tile is outside of the shower enclosure and above the tile on the walls.

So you guys are saying that a gap is actually desirable? Damn, pure dumb luck!

Gardner, why did you fill your gaps with that foambacker rod?

[briano96]

I'm thinking of installing a heatpad under the ceramic floor tile in my bathroom. Would I install it on top of the 1/8" Ditra using unmodified thinset or beneath it using modified thinset?

[cx]

You would install the heating mat per the manufacturer's instructions. You would install the Ditra on top of the heat mat per Schluter's instructions.

The Ditra always wants to be on top of everything but your tile.

My opinion; worth price charged.

[briano96]

Thanks CX

[gardner]

why did you fill your gaps with that foam backer rod

It helps keep the gaps from accidentally getting filled with thinset or grout. A gap filled with cement doesn't do its job so well.