Ideally tile should be installed directly on top of a surface like cement backerboard which is stable.
Tile over tile thinset.
As you re installing your tiles use a level to make sure the new floor remains even.
Thinset over thinset robert thinset will adhere to thinset just fine.
First clean and then sand the surface of the old tile until it feels rough.
Others prefer to use a larger notched trowel 1 2 x 1 2 in to apply the thin set.
You can put new thinset on top of old but only if.
Unlevel floors can eventually cause both layers of tile to crack the following steps are helpful tips when installing tile over tile.
Working in small sections spread the thinset over the existing tile using a notched trowel.
Tile needs a smooth level surface to be installed on.
So in short you can tile over tile as long as you re working on a fairly sound surface.
Without a somewhat smooth surface it will be difficult to properly trowel out new thinset.
Second apply a very thin coat of thin set mortar filling in the current grout lines.
How to install tile over old thinset grind it down.
If the substrate and thinset is solid then you can go over the top with new.
This could lead to difficulty getting the new tiles level and fully supported by the new thinset.
If all your talking about is 3 16 then thinset is a good solution.
However it may be worth noting that you may need to wait a little longer between laying the tile and grouting to allow the thin set to properly cure.
You can tile over exiting tile with latex modified thinset mortar but the bond might not be as sound as.
When laying tile over tile it is best to use a modified thin set.
You can add extra thinset under your new tiles if needed to ensure they re level.
Position your tiles according to the layout you choose.
Or larger and even more important when you re tiling over tile.
If this is not a good idea i can just pack the thinset thicker in that corner at the time that i lay the tile.
The modified mortar creates a stronger bond between the surfaces.
The big issue is going to be the smoothness.
Then i will mud with thinset and lay tile.
Some installers prefer to flatback each tile with the flat edge of the trowel before applying the tile to the combed thin set.
Epoxy tile adhesive may bond with almost anything and requires special solvents to remove.
This helps to prevent tiles from cracking.
Thinset with small amounts of latex added are primarily used for large format tiles and stone tiles to help absorb flex from floors and walls.
Complete adhesive coverage is critical on large tiles 12 in.