How can I create a waterproof tile patch where a wall was removed?

Question

We recently bought a house and the previous owner has removed part of a wall separating the shower from the bathtub. Sadly, he seems to have just torn it apart and covered it up with duct tape.

Now my question is, how can I cover up this hole between the two tiles while making sure it's waterproof? I'm afraid if I just remove the duct tape like this, I might get a leakage or mold.

I was thinking of finding small tiles to add between the existing tiles, any other advice is welcome, but I'm not sure how to close the gap between the top part and the ceiling.

Answer 1

If what is behind all the duct tape is the same as what is revealed, your idea of applying accent tiles and grouting is the best way to cover that.

The ceiling looks like a Sand finish which is done by troweling or rolling it on. Then paint to match. You may have to paint the entire ceiling.

Answer 2

Doing a very rough perspective crop & selection in Photoshop, it looks like you could fill the gap with a line of whole tiles. after removing the cuts. Might make the job better-hidden, if you can find a matching tile [or if the last owner sensibly kept spares…]

^{Click for larger. Copy/pasted tile tinted green for contrast.}

The ceiling looks like Artex to me. You may be able to patch across with a heavy sponge roller, perhaps a specialist, or you can try hacking chunks out of a cheap standard roller to give some of the randomisation. Roll out over the existing surface to blend it in. [It will never be perfect, no two artex jobs will ever match, even done by a pro.]