Firstly, good on you for opting to fix the bath yourself! This is a common problem; the silicone seal around a bath or shower will deteriorate over time.

It will, as you described, crack and peel away increasing the chance for a leak. This can loosen tiles, or as you feared, damage the ceiling in the room below.

So, here’s what to do. The first step is the fiddly bit – removing the old sealant. If possible, use a blunt plastic/wooden scraper or, if necessary, a Stanley knife blade (if you go for the latter, be careful not to scratch the bath’s surface).

Before you apply new sealant, make sure the surface is clean and dry. A good tip is to fill the bath with water; the weight of the water will cause the bath to flex and open the gap you need to seal, Always use a good quality mould resistant sealant. Cut the sealant nozzle at an angle and use a cartridge gun to produce a bead of sealant that’s a little larger than the gap you are aiming to seal.

When you’re ready to start, ensure that you have lots of kitchen towel to hand to clean up any mess and then run a continuous bead along the area that needs to be sealed. The sealant bead must then be pushed into the gap and shaped.

There are tools available to do this, but the best finish is usually achieved by running a wet finger along the seal, wiping away any excess as you go. It can take a little practice to get a really good finish so try in a small area first. Masking tape either side of the gap can help to improve the finish.

Leave 24 hours for the sealant to fully dry and ‘voila’, a bath you can be proud of.