Tiling kitchen spashback with gap between worktop and wall

Question

I'm planning on tiling a kitchen splashback (first time tiling project). Unfortunately due to curvature of the wall, there is a gap between the worktop and the wall. This varies in thickness between about 2mm and 9mm.

The tiles I'll be using are 6mm thick metro tiles (flat, no bevel), and I'm planning to use a 6mm square notched trowel – which by my research will mean the tiles will end up 3mm away from the wall.

I feel that there is a good chance that the tiles will slip down into the gap behind the worktop. My question is therefore: How should I stop the tiles falling down into the gap, and instead keep a level first row?

So far I have considered:

1. Plugging the gap with a strip of wood. Seems ideal, but unfortunately I don't have a suitable piece of wood nor the tools to craft one, and it is difficult to get hold of this sort of thing at the moment!

2. Filling the gap with caulk/grout/filler. This would be easy enough, but could I get a level enough surface to start the tiling from?

3. Tiling off a metal rule. I can't re-find it now, but I read somewhere that you can lay the first set of tiles on top of a metal ruler – presumably laid flat on the worktop? Could this help to form a temporary 'bridge' over the gap?

Answer 1

I like option three.

Put down painters tape first then slide the ruler to the wall and tape it down securely along the edge away from the wall. This gives you straight edge to work on.( assuming your counter is straight )

Once your tile is set ( 24 hours ) you can pull the tape, gently slide out the ruler and remove the other tape.

If you still have a small gap the caulk between the countertop and the tile should cover it.

Answer 2

I would suggest fastening the backside of the worktop to the studs in the wall from the cabinets below. This will prevent the gap from widening further in the future and eliminate the gap your tiles currently have to span.

Answer 3

If you mixed up a little thinset, you could apply it to the wall at the low spot, then with a straight piece of wood or metal, bridge the 2 high spots over the recess, and screed off the thinset over the area. Let it set for a day and you will have a straighter wall to work with and the gap should be gone. Do use painters tape to protect the countertop, and if you choose to, mark off the low area perimeter so you have a reference to apply the "filler"