How to Seal a Bath Properly

Whether it’s a new bathroom suite, a new tub or resealing a current one, sealing a bath should be a straightforward task. 

Sealant for a bath is a simple way to refresh a bathroom, especially if your current sealant is looking a little worse for wear. Not only that, bathroom silicone sealant will protect your bath from leaks, give it a smooth finish and prevent water from getting underneath the tub - which can lead to mould forming.

Plumbworld has made this step-by-step guide for how to seal or reseal a bath properly, with useful tips for each valuable part of the process.

Read on to find just how easy it can be, whether you’re a professional or looking to save money with some DIY...

Why should I seal a bath?

If you have a straight bath in your home - the most common type of bathtub in the UK - chances are that it is installed against at least one wall.

As baths contain large volumes of water, they are prone to leaking or water flowing over the edge. If this water gets down the side and underneath the tub, and collects on the floor, it can lead to flooding, rotting and a build-up of mould - which can bring health risks and repair costs.

Read more: How to Remove Bathroom Mould

Another reason to seal or reseal a bath is to give your bathroom a quick spruce-up. Tired-looking sealant can drag the visual appeal of a washroom down, so a smooth sealant is a simple bathroom refresh without breaking the bank.

What to seal a bath with

To seal a bath with silicone sealant - the most common method - you’ll need the following equipment:

  • Safety gloves
  • Safety glasses
  • Masking tape
  • Safety knife
  • Caulking gun
  • Silicone sealant - which can be bought from most stores and from Plumbworld
  • Silicone applicator - or a round-headed tool

An alternative method, and therefore requiring different equipment, is to use a flexible caulking strip. This is a self-adhesive that can be cut to fit the gap between your tub and the wall.

How to seal around a bath - step-by-step

Once you’ve got your equipment and tools, it’s time to start sealing your bathtub, which can take an afternoon to do.

We’re using a straight bath - single or double-ended - as an example, but this process will also apply to corner baths and whirlpool baths.

Firstly, tape the edges

The first step is to use your masking tape and place it around the edge of your bath, marking where you're going to put the silicone.

Work from the back corner of your bathtub - the corner furthest from your bathroom door - and keep the tape at least 3mm from the wall. This will ensure a neat finish to the silicone.

Preparing the sealant

Wearing your safety gear from this point on, use your knife to cut the silicone open. Before attaching the head or nozzle of the silicone, cut the tip as close to a 45-degree angle as possible - this will make applying it much easier. Then place the silicone into the caulking gun.

A caulking or silicone gun acts as a pump for squeezing the silicone out of its tube.

Apply the sealant

Get as close as possible to the edge of the bath you want to seal, and then apply the silicone by pressing the caulking gun trigger. In a smooth movement, begin with the furthest corner - as you did with the tape.

This will make sure you don’t touch any new silicone you’ve put down. For example, if your tub is surrounded by three walls, start at the ‘top’ and go in a C-motion. If possible, apply silicone to both the base and the wall.

Tip: Fill the bath when you apply the sealant, the weight of the water will ensure the sealant won’t crack when the bath is used later. This gives a real representation compared to an empty tub.

Smooth the sealant

Using a sealant applicator, a wet round-ended tool such as a wooden spoon, or even a wet fingertip, smooth and shape the sealant edge at an angle. This will help the sealant to shed water back into the tub - particularly if it is a shower bath.

This is an important step because it ensures no dirt, germs or even mould can get in behind the sealant.

Sealant can take up to 24 hours to set, so make sure your bathroom, or the bath at least, is off-limits for that time.

How to seal a bath with a large gap

If there is a large gap between your bathtub and the wall, it could be down to poor installation or something preventing it from being positioned - seated - closer.

The main action to take will be to remove any silicone or grout that is already there and re-seat the bath closer to the wall - to reinstall it. This will then allow you to seal the bathtub as you normally would using the above process.

If you can’t or don’t want to re-seat the tub, there are two potential options. The first is to plug the gap with an adhesive and bonding material. Once this has dried, you can seal the bath using the above process.

The second choice is to use flexible caulking strips. This is a self-adhesive tape that you cut using a safety knife to fit the length and gap required. Once cut, simply peel off the backing and press the strip into place.

How do I remove sealant?

To remove sealant that is worn, tired-looking or covered in mould, you’ll have to cut it and use a flat-headed screwdriver to lift it away.

Using a safety knife, gently cut the old sealant and scrape it away with the screwdriver until you have removed as much as possible. Use your finger to rub the remaining strands off or use white spirit - turpentine. Use an old cloth and rub it over the strands to remove them.

Be very careful doing this as you don’t want to scratch or damage the surface of the wall or tiles.

If you follow these steps, you should find sealing and resealing a bath a straightforward job that isn’t too time-consuming.

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Don’t forget to check out the rest of our blog for more bathroom advice…

What Size Bath Do You Need? | How To Fit Bathroom Wall Panels | How to Fit a Bathroom Vanity Unit