How to Seal a Bath


If the edge of your bath is unsealed, water can drip down between the bath and the wall and cause flooding, mould and rotting of the joists. Therefore sealing the gap between bath and wall is an excellent idea.

There are two main methods of sealing a bath. The first is to use a specially purchased sealant strip known as flexible caulking. The second is to use silicone sealant which gets squeezed out of a ‘gun’ and is pumped out as a quick drying semi-liquid with the look and consistency of toothpaste.


Which method of sealing a bath is best?

mastic gun
mastic gun

Both methods are excellent but the silicone tends to be less effective on wider gaps. However, after trying both out on many occasions I find the skeleton gun method with Evo Stik Sealant easy to apply and provides a smooth finish if you run the back of a spoon dipped in washing up liquid along the bead.

Here are both methods of sealing a bath described in more detail.

Caulking Strip Method

Flexible caulking strip makes it easy to seal around the top rim of a wider bathtub gap. Applying caulking strip is quite simple. It is a matter of just cutting the self-adhesive strip to lengths needed, peeling off the backing and pressing the sealant strip into place. The strip is thinner in the centre, to create a hinge, so one half covers the wall and the other covers the bath.

caulk strip sealant
caulk strip sealant


Some DIY stores sell a special plastic tool for pressing the caulk strip down to achieve a good finish, but a V-shaped wooden offcut seems to do the job just as nicely. Whatever you use, getting a good seal is essential. Take particular care if you are pressing the caulk strip against tiles. Ensure you push it in to the grouting recesses or else the seal will fail.

If you are re-tiling the bathroom, then a length of rubber seal that sits behind the bottom tile, with a rubber lip extending out to cover the bath edge is perhaps the most effective of all bath sealant solutions.

Silicone Gun method

bath seal
bath seal

A Silicone gun is basically a pump for squeezing silicone out of a tube. Loading the silicone sealant tube is easy, but the applicator nozzle needs cutting to size to allow silicone to get out. Applying the silicone to the surface is a matter of running the nozzle along the gap between wall and bath, pumping as you go.

Instead of manually pumping, you can now buy the same silicone in a pressurised container. As you push the nozzle to one side, the silicone comes out automatically. This can be either really easy or really difficult depending on how steady your hands are.

The secret to a good looking result is a smooth application,, which takes a steady hand and putting a finish on the silicone sealant. This can be reasonably well done using a finger coated with a bit of washing up liquid.

The washing up liquid stops the silicone sticking to your hands. Run your finger smoothly along the sealant bead to leave a flat even finish with no lumps and bumps. This is an important step because no dirt and germs can accumulate in your bath surround if there are no places for them to hide.

However, better than a wet finger is a purpose made finishing tool comprising a plastic handle and an edge made of rubber (or like the video below the whole thing made of rubber) . They sell them in DIY stores; cost less than a couple of quid and produce a beautiful bead with no effort. I now use these exclusively, simply because of the quality of results they produce.

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About the author

Loves to learn new things and make stuff...properly. Born and living in the Thames Valley west of London, England. I have an office job during the day, but evenings and weekends are all about making.