Floor prep questions

Discussion in 'Flooring' started by MarkS, Dec 10, 2017.

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  1. Dec 10, 2017 #1




    New Member

    Dec 8, 2017
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    Wife wants tile on the floor. After having just removed tile from this floor I'm hesitant, but may give it a shot.

    Current situation: Peer and beam house, 3/4" tongue and groove exposure 1 plywood over 2x12" joist that are 16" OC and span 12' with 1 girder in the middle of the 23" room. It appears the plywood was glued to the joist and stapled but I've added 2-1/2" construction screws to ensure a solid base. The floor is 3/8" or so out of level across 23' that I'm willing to live with as it seems lifting the end would flatten this room but through another room out of level. Seems as though the outer foundation walls are no exactly level to me. Additionally, there's a need some SLC or ???? on the floor to flatten it. Presently, the floor feels very solid with little to no bounce, squeaks, etc.

    FYI, when I started, on top of the above plywood was felt paper + 5/8" particle board + linoleum + 1/4" hardibacker screwed (no thinset underneath), + thinset and 12x12 tile. We had both cracked tile and grout joint issues with that floor. Many of the tiles popped up pretty easily as I think they tried to flatten the floor as they went with thinset.

    Given that I'm not shooting for level on this floor, only flat and solid, I "believe" most of the low spots can be corrected with 1/4" or less of SLC. However, reading one of the SLC instructions they state that I need a minimum of 1 - 1/4" plywood with SLC and that I need lath in the SLC, all of lath I've found is about 1/4" thick itself so I don't know how one would feather that out to smooth.

    Finally, the question(s)...\

    - Do I need another layer of plywood on top of the 3/4"?
    - Do I require lath for the SLC to hold up?
    - Any reasons I should be hesitant to lay large format 12/24 tile here?
    - Where might I find the SLC barrier stuff, or what's a reasonable alternative to the SLC barrier?

    Last edited: Dec 10, 2017

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