Please help me solve my grout woes!

[SquidgyMaltLoaf]

Our shower started leaking through the ceiling. It's definitely because the sealant failed, despite it only being a few months old, so I've taken it all off and discovered that the grout between the bottom row of tiles and the shower tray has shrunk and / or disintegrated. It was proper waterproof grout and covered every square mm of the gap and was fully dry before it was sealed. I know because I did it..!

How can I make sure it doesn't shrink again? What did I do wrong?

did you seal it before you tiled it?

Do any of the following apply to you op?

*Was the grout new when used, or was it an old supply?

• When you mixed the grout, did you put the right amount of water in? Too much can cause the grout to 'shrink' back and sink as it dries, as the water evaporates out of it.

*Some baths/shower trays are slightly flexible, so when your weight is added to them they can move, pulling apart the grout and bath/tray.

Should be silicone sealant there, not grout.

Defo silicone seal required there. That's not the place for grout when silicone is available.

Sort to repeat but yes grout is just for between tiles, you need flexible sealant between shower tray and walls. Ideally you need to simulate the weight of a person standing there while it dries e.g with a dustbin or large trug full of water. Then its 'rest' state is when it is pushed down, and when no-one is there the sealant is being compressed up rather than stretched down.

I put sealant on over the grout. Should I just silicone and not grout the gap at all then?

We tanked our shower and the surround so as not to rely on sealant or grout! This is what you would do in a wet room but it works for all shower areas and gives peace of mind. Sealant is not grout. It is flexible and should move as the tray moves. We don't have these sorts of shower trays - ours are heavy and ceramic. I would get a plumber to lift the shower tray and seal the area properly, especially if it is a flexible shower tray.

even a heavy ceramic tray will move if it is on a wooden floor. If the floor is chipboard and has been wet is softens like weetabix (but is not as tasty)

The plumber silicone had sealed between the tray and the backing board before I tiled it. We had a leak initially that turned out to be a loose joint in the waste (hence why I know what happens to chipboard ceilings when they get wet ) and they also resealed the whole thing when we had another leak. That sealant started lifting from the tray after a few days so we just redid it ourselves.

So - if I do one line of sealant under the tiles as far back as I can, then another to finish it off once the first one is dry, will I be able to stop water appearing on the kitchen ceiling?!

*had silicone sealed. Stoopid phone.

hope so

you will need to get both surfaces free of dirt, soap, oil, limescale.

If you haven't got one, look out for a little hard plastic triangular tool for pressing it to a neat shape. I can't remember the trade name.

You can get mould-resistant silicone. Also a sealant-eater for cleaning off the old stuff.

If there are any special tricks they might be on the sealant-makers website. People say Dow Corning is a good brand. I am not very good with silicone.

Make sure it's not only clean but bone dry before the silicone goes on. Good luck we've just done ours, we also tanked first as a previous poster did and the seal around the shower tray where it meets the tiles is Silicone.