Floor Tile Problem (tile On Tile?)

[SJPurdy]

Here is an incredibly technical drawing I've just done for you. Neither tile touches the other. Silicon covers the gab. Both tiles could theoretically move into the gab, should expansion and retraction require it.

View attachment 82190

Silicon would usually match the tiles. I'd never use clear. You'll see the gab through it.

I would lay the floor tiles up to the walls leaving and expansion gap to the walls (which I would seal in critical (wet) areas.
I would then fix the wall tiles but leave an expansion gap at the bottom between them and the floor tiles, which would then be filled with an appropriate colour Silicon sealant.
This also allows for movement/expansion/contraction in both the walls and floor.
When we say joints filled with sealant it should be noted that the sealant should only bond to the tile edges and not he bottom/back of the joint. In critical movement likely applications or deep joints a bond breaker tape or joint filler will be required. That said I think in most domestic applications the joint will just be filled with sealant!

 

[Brian Holz]

Thanks for the replies, the tiling was finished last friday. Just hoping its an easy fix if possible by laying tiles over tiles.

As long as you use an acrylic additive in your Thinset morter to lay the new tiles over the old (well, other new tiles) you should be fine.
Use black Silicon of you can find it, leaving a 3mm gap between the wall tile. This should be siliconed.
I'd you can't find black Silicon, 100% pure, then grout out the 3mm space with the black grout, but then you MUST use a 3mm bead of clear Silicon that will cover the 3 mm grout on the floor AND 3mm up the wall tile.
I know this for a fact. I have done it many times for the past 20 years, and have seen, recently, a few that are still holding up.
I hope this helps you. If you have any more questions, please message me!

🙂

 

[olly330]

Thanks everyone, quality replies that speak volumes for your qualify of work.

 

[magga]

Mapei Mapesil AC you can get in black

 

[SJPurdy]

I'd you can't find black Silicon, 100% pure, then grout out the 3mm space with the black grout, but then you MUST use a 3mm bead of clear Silicon that will cover the 3 mm grout on the floor AND 3mm up the wall tile.
I know this for a fact. I have done it many times for the past 20 years, and have seen, recently, a few that are still holding up.

🙂

I know other tillers still do this "fill joint with coloured grout and then clear Silicon over". I did it myself 20+ years ago when getting coloured Silicon wasn't so easy, but it is wrong in my opinion.
The joint is left and filled with a flexible sealant (over filler/bond breaker as necessary) which then allows the joint to be compressed or stretched due to movement from many sources. Filling the joint with grout first means that the joint can't be compressed and any movement (eg temperature caused expansion of the floor tiling) will then put additional stresses on the floor and/or wall tiles.
Most good tile grout suppliers now stock coloured silicones to coordinate with their grout range. For me it was sometimes more convenient to pick up a tube or two of Mapie Silicon from Screwfix as it is closer than other outlets (at times it was even cheaper!).