Leveling bathroom floor before tile...

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Old 10-06-11, 09:09 PM
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Leveling bathroom floor before tile...

Hello, recently my uncle has remodeled my bathroom floor and it had to be ripped up because he did a bad job. What was layed was the subfloor, cement board, layer of thinse,t Schluter Ditra Underlayment, layer of thinset and tile. I had to rip up the tile and Schluter Ditra Underlayment, which left the backing (thin layer of cotton). My question is I need to lay some floor leveling compound and I need to know if I can lay that over that. Then put down the Schluter Ditra Underlayment and tile over that or do I need to rip everything up? Thanks in advance!!
 
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Old 10-07-11, 08:08 AM
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Welcome to the forums.

What is the subfloor made of and how thick is it? What are the dimensions, spacing and span of your joists? Ceramic tile or natural stone?
 
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Old 10-07-11, 08:39 AM
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Have you determined the cause of failure and corrected the problem. Is the joist system and subfloor adequate for a tile floor? Did your uncle install ceramic tile or a natural stone floor?

Cement board and ditra are both underlayments for tile, and you would not ordinarily use both. It would be better to use a second layer of plywood, then ditra. Cement board does not add to the strength and stiffness of the floor like plywood. Ditra and cement board provide uncoupling and a friendly bonding surface for the thinset and tile. Ditra does a better job of the uncoupling.

If you have determined that your joists and subfloor are adequate, and that your cement board was installed properly (bedded in fresh thinset, screwed according to manufacturer instructions, taped and mudded), you can use slc over the cement board. If its only a few low spots, you can also use a cement based patching compound. If you decide to go the slc route make sure you take the time to read the manufacturers instructions, including plugging all the holes and daming off the perimeter, and using the recommended primer prior to pouring. If you have not worked with slc before, do not get the rapid setting slc.

If you provide more info, we can give you better advice.
 
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Old 10-07-11, 08:45 AM
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No Pro...but you should also have thinset between the subfloor and CBU I'm pretty sure.

Also....if you were using Ditra...why the CBU at all? You could have just used the subfloor as is (depending on what existed) or added plywood over the subfloor then the Ditra.

The Ditra instructions spell everything out pretty clearly for almost any situation...http://www.schluter.com/media/DitraHandbook.pdf
 
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Old 10-07-11, 11:10 AM
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Everything under the SDU is layed correct. I had to pull the tile up because it was layed incorrectly and it wasn't straight. So with pulling up the tile I also pulled up the SDU and in turn it has left a little cotton backing on top of the thinset. I noticed that the floor is not level (its off my about an inch east to west - bathroom is fairly small, about 6x8) I want to level it out that way when I put tile on the wall I get a straight line all the way around. If I don't it will look crazy. The house was built in 1931
 
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Old 10-07-11, 12:06 PM
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Thats a sizable amount of slc you will need. Its expensive stuff. Read up on the products you intend to use. Slc's can only be poured to a certain thickness in one shot so make sure the one you pick can be poured to the thickness required. Have a helper or two on hand as you need to work quick. Have buckets, water supply and mixing drill ready to go. Slc sets up pretty fast, and if you cant keep up, you will have a mess on your hands. Plug all the holes in the floor, around the closet flange, around the perimeter walls and accross the threshold. Use tape, self-stick foam insulation and whatever else works for you. If there is a hole that you missed the slc will find it and pour out it. Use an slc rake to move the material as needed. Some slc's flow a lot better than others. You will probably need about 4 50lb bags of slc, but buy 5 and return one if you dont need it. You do not want to run short.

Before you start, scrape and grind all the loose thinset off the cbu and vac and mop it clean. Apply primer to the floor and let it set up according to manufacturers instructions.

You can set tile directly to slc, you dont need the ditra.

The slc I use is TEC EZ Level. It comes in 50lb bags. Tec's 560 primer is required. This stuff flows beautifully. Work time is about 15 minutes. I believe it can be poured to 1.5". This is what I like to use. Its not sold at the big box stores. There are other manufacturers that make good slc's as well that are sold at the big box stores.

For the record, tile doesnt need level, it needs flat. As to the walls (if you choose not to level the floor) you could cut the bottom row of wall tile accordingly, to level off the first row of tile and then tile up from there.
 
 

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