I have recently bought my first house, and have a problem with the tub. I’ve re-caulked around the edges (using all-purpose waterproof sealant from Wilkinson’s) multiple times, but water still seeps into the caulk and drips down the side of the bathtub when the shower is run. The tub moves downward when you step in, and this seems to be causing the caulk to crack and allow water in.

What can I do to either stop the tub moving, or else keep it in place while the caulk dries? I tried filling to the brim with water and leaving it full overnight to weigh it down, but the seal still cracks. I pulled out most of the old sealant before I started, but there is a sort of plastic strip around two sides of the bath that I didn’t remove, as it seems to be attached with grout. I thought it might be structurally important so I didn’t pull it out, but squeezed the caulk underneath and on top of it. Should I rip it all out and start again? Do I need to use a better sealant than the cheap Wilko brand? Or any other ideas?

If the tub is moving “downward” you to address that problem first. The tub should not move, I am assuming it is a fiberglass or acrylic tub unit. You need to get a look underneath the tub and make sure there is some support there, either mortar, foam, or plaster. If the tub is not properly seated your issue will continue. Once you have the proper bedding for the tub, then you can proceed caulking around the tub with a 100% silicone. I would recommend doing a search for “how to install a tub” this will show you what I am talking about. Also once you are ready to caulk around the tub, fill it up with water so it is weighed down, and caulk while the tub is full. Hope this helps,

I do not think the problem is your grouting. It seems that the tub was not properly installed. You have to pull the tub up and mix a little cement. Then put the cement on the floor as a footing for the tub. This does a couple of different things it keeps the tub from moving when you put water and a person in the tub. Which in turn makes the tub last longer cause noe it wont have the tendency to crack from being shifted.