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Floor Prep Questions Before Stone Tile Install

Posted by enduring (My Page) on
Fri, May 25, 12 at 19:09

Hi, I have removed my plaster on 2 walls getting ready for new BR remodel. I have removed the fixtures and the old linoleum. Now there is glue residue that is covering the old T&G fir flooring that I wanted to keep as a subfloor. Last fall I asked this forum about prep for this floor and now need help getting some clarification on my plans.

I need to get my floor ready for tile and warming system. What I have planned is to keep the 3/4" diagonal subfloor & the 3/4" fir flooring, creating about 1.5" of subfloor. The wood is all old wood with nice grain. The joist at this point are 21" OC and I will be adding another joist between each of these. I will not sister these joist, nor will I use blocking. I will screw these joist into the diagonal subflooring. The long joist run about 10' free span. The width of the room is about 6.5'. There are 5 joist total. The joist become about 10" OC, I guess, after inserting the extra joist. The crawl space to do this will be inconvenient but can be done (I'm going to have my 21yo son do it).

So, now that I have the linoleum off. I was going to screw down 3/8" exterior grade plywood, into the top layering of flooring. I was not going to glue the plywood. I was not going to remove the old linoleum glue either. I was just going to make sure that the fir flooring was smooth before installing the plywood.

Then, having a nice surface to work with I will apply my electric floor warming system. I will cover this heating system with self leveling compound (SLC). I have read Staceyneal's post on this topic and will use her techniques that she learned from Mongoct, to seal any gaps, preventing escaping SLC. She had a great post on the use of SLC for her BR remodel.

Ditra applied over the SLC using modified thinset.

Install 12x6" slate tile with unmodified thinset over the Ditra.

1) Is my plan sound?

2) Is it ok to not remove the adhesive before putting in the plywood? I REALLY think it is TOO hard to remove this adhesive!

3) How close together do I need to space my screws on the plywood when I install it over my fir T&G?

4) Do I need to prep the plywood before the SLC?

5) Do I have the plumber come in and put in toilet, tub, and sink rough-ins before the SLC or after?

6) Have I missed something?

Thanks for taking the time to read this post. If you have input I would welcome it.

Follow-Up Postings:

RE: Floor Prep Questions a Link from My Earlier Post in Nov.

Here is a link to my post that I made last November.

Here is a link that might be useful: My post on tiling this floor last November

RE: Floor Prep Questions Before Stone Tile Install

1) It sounds good to me. Just make sure you use a primer for the SLC on the plywood before you pour.

2)Yes, it's okay. THe only reason you'd need to remove it is if this were the bonding surface for the thinset, which it's not.

3)Every 6"

4)Already covered that.

5)If the tub's going to be a standard tub (as in NOT a clawfoot), then the tub should go in second (after the plywood), even before the SLC. As for the rest, it all goes in once the tile is COMPLETE.

6)Not that I can think of off hand.

RE: Floor Prep Questions Before Stone Tile Install

Bill V. Thanks so much for responding! I have been planning my purchases for this phase and waiting anxiously for a response to my floor questions :)

So Bill V., regarding #5 question - I'm asking just about the plumbing rough-ins, like the hole for the toilet, and the "through the floor" tub plumbing pipes. I would think that the plumber would want to cut through the plywood and subfloor before the SLC is in. I haven't asked my plumber Kevin yet what he wants, and he is ultimately who will make the call. But if I could pour before he made his rough-ins it would be easier for me to not have to work around the extra plumbing and openings.

Another question about the SLC - is the SLC not strong enough for the weight of the tub? I was going to install the tub after the SLC, I didn't even question this one. I have a standard tub, alcove type. So, I would think that when installing the tub, before SLC, I would want to caulk the tub at the floor to prevent the SLC from seeping in under the tub. I will have one end of the tub open, for a built in cabinet that will come after I tile the floor including this area. This cabinet will house the plumbing. I will need to create some sort of dam at this end. Staceyneil posted some time ago about how she made a successful SLC pour and described how she made a dam out of 2x's.

Again thanks so much for your input.

RE: Floor Prep Questions Before Stone Tile Install

ALl the rough in work gets done before pouring the SLC. The toilet flange goes in, the holes get cut for all the pipes, etc.. (you didn't think we were going to make this easy on you, didja? LOL) Seriously-- you can use duct tape to make dams around the holes. As for the tub, I'm not worried about weight or anything else. If it's a standard tub, the tile will abutt it on the floor,, so there's no need to go under it with the SLC or the tile. Also, I'm assuming you're going to lay the heat mats down first, BEFORE the SLC, and embed them in it, right? You certainly don't want the heating system going under the tub, and you want the rough work done before you lay down the heating system (the less traffic and work you have to do over the system, the better, until the tile goes down).

RE: Floor Prep Questions Before Stone Tile Install

Thanks, The heating will be cable and I will place it @3" spacing (or as directed by manufacturer) around the center of the room, extended about 4" under the open shelved vanity, up to the tub :), not in the cabinet :), sort of around the toilet, like this:


Ok, got it:
1) plywood down
2) plumber to put in rough-ins and the tub.
3) lay down my heating as directed.
4) secure the area and pour SLC.
5) I will then put Ditra down as directed on the label using modified thinset.
6) The tile goes down using unmodified thinset.
7) Grout with Spectraloc, because this is a hard working bathroom for my family's dirty farm feet.

Right ?

RE: Floor Prep Questions Before Stone Tile Install

Where the "800 sq. inches" is behind the door, I wouldn't bother heating that. Not too often that you'll be walking around back there.

RE: Floor Prep Questions Before Stone Tile Install

Thanks, I might just make that area about 6 inches wide instead of the about 18" that it is now. Thanks for all your help. When I get this part done I will post the floor.

RE: Floor Prep Questions Before Stone Tile Install

Good deal.

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