Hi,
I’m currently getting floor tiles replaced in my home with porcelain tiles. In the hallway in front of one of the bedrooms (which was formerly part of the garage), there is a plywood sheet that is about 6.3×3.2 ft. The area that the plywood covers was also part of the garage. Beneath the plywood it is probably pretty hollow with some supportive materials (the previous homeowner did this). The tile installer told us two things:
1. Apply the tiles with Liquid Nials
2. Take out the plywood and replace it with Durock and then apply the tiles.
I have a few questions:
1) What is the best option for applying the porcelain tiles on that plywood area?
2) Should I just leave the plywood and apply the tiles like normal?
3) Should I leave the plywood and put some type of cement sheet before applying the tiles?
I have encountered like two small patches of mold behind wood baseboards throughout the house during this tile installation process, this house is quite old, it was left unattended for a few years, and the previous homeowner was quite irresponsible with their changes. So-
4) Should I remove the plywood to check for mold, fungus, etc? <- I am quite concerned about this!
Please say so if more context or info is needed. Also this is a decision I need to make really quickly.
Thank you!
Replies
You need at least an inch of plywood, preferably 1 1/2 inches, before you lay tile which sounds like you're going to have to restructure that area to get it flush with the other floors. The top layer can and should be cement board.
Yea I’m not even sure how that works. The concrete of the rest of the floor and the plywood are already level because the previous owner did not put any cement board before installing the old tile.
You'll need to break out a drill and punch a hole through the plywood to see how thick it is. If it's not thick enough you need to pull it up and do whatever remuddling is needed to get a heavier base for the tile. There is another consideration too, sound. As you walk across the floor the area with plywood will be like walking on a drum compared to the concrete-floored areas. Maybe you can drop the plywood down far enough to pour 3 or 4" of concrete and solve both problems at once.
What's the plywood on top of? A slab? If you're unsure of how well the plywood is supported, do not install tile over it.
Liquid nails should not be used for installing tiles, especially not on a floor.
I'm confused by your comment about the plywood and cement being level already. Is the plywood on a sunken area of slab?
Tile requires a rigid and flat substrate before installation.
If the plywood is over a lower section of concrete, that area could be built up with deck mud or self leveling cement. A crack isolation membrane is a good idea when tiling over concrete. I believe both mapei and laticrete make thin sheet products, or if you need extra thickness to meet up with other surfaces, schluter ditra comes in 1/8 and 5/16 thicknesses.
If you're over wood framing, 5/8 t&g ply is the bare minimum for porcelain installation. On top of that could be cement board or an uncoupling membrane such as ditra or stratamat.
You should definitely find out what's going on under that sheet and how thick it actually is. Do you not want to pull it up because some of that wall or the trim is over it? If there's any flex, the tile installation will probably fail. It's not just the thickness of the subfloor, it's the support structure beneath it that's important.
Gluing tiles down with liquid nails is not the way to go and durock isn't structural, it goes over a subfloor, not right on joists or whatever bracing you have there. If the installer is actually telling you both of these things I'd be suspicious.
Hopefully I'm not offside by recommending you check in at the john bridge forums but that's all tiling and you can get a lot of good help there.