Flooring Tile - Demo existing tile, prep for new, few questions

House: 1987 construction ranch with full basement

Floor: Previous DIY'er Tile over durarock over 2 layers plywood

Question: Is 1 layer of plywood i.e. the original subfloor strong/good/firm enough to tile over given I'll be using a layer of durarock.

Situation: Once I demo'ed the tile and durarock board and removed the center island, I descovered to my dismay that someone had doubled up on plywood. The original subfloor is visable at the edges of the kitchen, and it became obvious where original cabinets had been, they were set on only 1 layer of plywood. I'll be tiling approx. 700 sq ft. Kitchen entry way and hallway to 3 bedrooms. If I must keep the 2 nd layer, i'll have to install a 2nd layer throughout the house to get it level. If I can loose it, I pray to the renovation gods that they didn't glue it down.

Kitchen island, 2nd layer subfloor put in around it
http://img.photobucket.com/albums/v228/harleysilo/100_0970.jpg

Closer....

http://img.photobucket.com/albums/v228/harleysilo/100_0971.jpg

edge or floor..

http://img.photobucket.com/albums/v228/harleysilo/100_0972.jpg


I'd appreciate anyones opinons or direction.

Thanks,
Nathan

The truth is the second layer is a blessing and should remain.

Cement board will offer NO structural assistance whatsoever and is nothing more than a good and proper "tooth" for the thinset to bond with. The cement board should be installed in a bed of fresh thinset by the way.

The Tile Council recommends that your substrate be a minimum of 1-1/8" to 1-1/4" BEFOR the cement board.

From the pictures I also see the need to grind the existing thinset off the surface of the plywood before continuing in that area. This can be done by renting a 'floor machine' and using a very coarse sand paper.:)

Thank you for your input. I have an additional issue related to this project. It is that the subfloor is not level. Picture a line drawn down the center of our home the floors are level on either side of the line, however overall they are 1/4 to 3/8 inch off. Possibliy more, will know tonight. That line runs through the kitchen, and down the entry way, areas where I will be tiling (one continuous run). So I either have to make up the difference with thinset, or another (3rd) layer of thin plywood for the kitchen.

Suggestions?

Area in entry way where original hardwood floor dips down towards carpet.

http://img.photobucket.com/albums/v228/harleysilo/100_0968.jpg

http://img.photobucket.com/albums/v228/harleysilo/100_0969.jpg

I don't yet have a pic or the kitchen floor where this is also the case, but I've drawn a few red lines on this pic to indicate the general path....

http://img.photobucket.com/albums/v228/harleysilo/kitfloor.jpg

You'll never do it with thinset, forget that!

Plywood won't change anything, if the floor slopes now, it will slope when the plywood is added.

I'll make an assumption at this point.

I am assuming your home's structure has a beam running through the center under where you are indicating the red lines. This beam is probably supported with collumns down below. These collumns are either supported by a basement slab or on spread footings under the house.

What has happened is that over time the perimeter foundation has settled due to on and off exposure to the outside elements of seasonal changes whereas the interior collumns and footings have enjoyed some protection from this exposure and these seasonal elements. So you have the center beam staying in place while the exterior beams (foundation) has drooped a little.

Now you have a 'floor-crown' in the middle of the house. To change all of this would be very expensive. You could jack the perimeter foundation but this would be very costly and create the need for interior repairs as a result of the jacking. Or you could fill the low-end of the floors (with Self Levelling Compound) which would be a much less intrusive and expensive approach.

OR, you could live with it and install a flexible grout joint exactly on top of that crown thereby tiling in both directions away from the crown and it wouldn't be any more noticeable than it is now.

The floor doesn't have to be 'true-level' to receive tile.:)

I realized you now have an answer more than you bargained for but I am trying to think this through and show off a little bit.:)

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MAN this place can be a PITA.

Anyone else have any suggestions?:wall: :wall:

Every grout has a color/texture matched caulk you could use for the soft joint as Bud suggested. That requires you to establish your layout such that a grout joint falls over that line. That may not give you the layout or balance you want. The other option would be self leveling cement as Bud also mentioned. You could forgo the cbu entirely and use a membrane instead. Noble CIS, for example, is only 1/16" thick installed and no nails or screws either. Their site is www.noblecompany.com

Last option would be to do a full mud job You could get away with about 1" thickness over the hump and have it thicker as needed to absorb the out of level areas. This would be over the original 3/4 plywwod subfloor, eliminating bot the second plywood layer and the backer. This might work depending upn you home's supporting structure. Transitions are available for the higher ceramic floor level as needed

Well, my father and I jacked the kitchen floor joist where the meet the main beam (centerline of the house), and re-hung them 1/2" higher. The kitchen floor is now level. In identifing the real problem, and fixing it, I have now determined I want to fix the remaining area where the joists have fallen 1/2". Here's a pic to help explain the issue...

http://img.photobucket.com/albums/v228/harleysilo/tile%20floor%20project/floorjoistdiagram.jpg

So the remaining 25" section where the joists have "fallen" has two separate walls above it. They run down the centerline of the house, but run next to the main beam not over it. To jack that will obviously reguire a different method than the hi-lift jack and 2x4's we used for floor joists in the kitchen (no wall and very little weights, could push them up with a 2x4 withouts jack).

Anyone have any suggestions about this process?

I've read this.... http://www.hammerzone.com/archives/framecarp/supplement/floor/joist1/raising.htm
and
http://www.hammerzone.com/archives/letters/foundation/house_raise.htm
and that's what I intend to do....