How to fill a large gap between tiles and shower floor?

Question

Hi there,

Firstly, thanks to this site for all the advice over the years (long time user, first time posting).

I’ve noticed grout coming away from the base of my shower, where it’s been used to join the tiles to the shower floor. I plan to regrout at least the bottom few tiles and have purchased everything recommended in the Bunnings guides for this (except a multi tool).

My home is an old 1970s apartment and there is some movement. Typically the tiles would stop closer to the shower floor. Maybe it sunk and was repaired? In any case, I will have a big gap (about 12mm) to fill. Should I use silicone for the whole bottom join? That might help with future building movement. Any additional advice you can offer is appreciated!

Photo below. Thanks for your help!

Jack

MitchellMc · Answer

Could be a bit risky, but I think you'd get away with it @JackF. If you think you can use the filler rod with only one application of silicone, I'd go that route. You just don't want to have a whole mass of silicone trying to cure at the same time, as that can take weeks.

Mitchell

JackF · Answer

Hi Mitchell and thanks for your reply, that’s really helpful information. I agree that using a narrow row of tiles at the bottom would have been much nicer!

I’m happy to fill the gap with multiple layers of silicone. My only concern is curing time (72 hours per layer) and not being able to use the shower! Is it risky to cover the bottom edge with a bit of plastic each morning for a couple of quick showers? I have flashing tape too.

The gap is only about 15mm deep, which is shallow for the filler rod, but if it means I can finish the job with only one application of silicone, perhaps that’s the way to go. It seems I, like my predecessor, can be tempted to cut corners.

MitchellMc · Answer

Welcome to the Bunnings Workshop community @JackF. It's sensational to have you join us and many thanks for your question on filling shower gaps.

No need to remove the post as even your solution is helpful information for others.

Undoubtably having a flexible joint between the tiles and shower tray would be a good move. That being said, 12mm is quite a wide area to be filling with silicone, though it is doable. The gap filler rod is predominantly used to fill deep gaps, but it doesn't assist with wide gaps. What really should have happened here was those lower blue tile should have been shifted up towards the white, reducing that large grout joint above them and then thin trimming tiles added below. Then standard width grout and silicone sealant could have been used to fill that standard-sized gap.

Once you've removed the compromised grout, you might be able to insert a filler rod, but these work by being compressed into position. Given the width of the gap this might not be possible. I suspect you'll end up filling this gap with multiple beads of silicone. Remember to allow them to fully cure before applying the next. Once you are close to the surface level, tape up either side of the tiles and tray and run one final bead, smoothing it off with a silicone tool. Spritz the silicone with some water with a few drops of dishwashing detergent before smoothing, which allows you to get a very fine finish.

Here's a helpful guide: How to apply silicone sealant.

Please let me know if you have any questions.

Mitchell