Sealing your bathroom fixtures and fittings

Getting to the stage of sealing bathroom fixtures and fittings is such a satisfying feeling. At this point, a lot of the hard work involved in installing a piece of bathroom furniture is almost complete. It’s not long now until you can relax and bask in the glow of a job well done (or move on to your next bathroom…).

As you know, the sealing process itself isn’t too involved and is one of the simpler tasks to carry out during your bathroom project. That being said, this doesn’t mean it doesn’t take skill and attention-to-detail. However carefully thought out they are, bathroom designs never look stylish and professional unless they are neatly sealed.

Different bathroom suites require the full array of your sealing skills, adapted to each specific item.

  • 1. Preparation

    Get your tools together

    To get the finish on your sealant right, you’ll need the best tools for the job. Naturally, the most important item is an applicator gun for an even spread of silicone sealant. See our range of sealant guns to upgrade your current gun or to get an idea of the range of options out there.

    You may also want to get a silicone smoother to keep all your edges neat and smooth. However, depending on where you’re applying the sealant and how experienced you are, you may find you can smooth the surface with just your fingers.

    Check your colours match

    Check carefully that the tube of silicone you’ve bought is a good colour match for the sink, bathtub, toilet or shower. If it’s the wrong shade it will stand out, and this is the last thing clients will want from a sealing job.

    Apply masking tape

    Masking either side of the sealing line is essential to protecting your bathroom tiles and ceramic surfaces and achieving a tidy finish.

  • 2. How to seal a shower or bathtub

    Remember: when it comes to sealing showers and bathtubs, the sealant you use must be a flexible one. It may seem obvious, but it’s an essential component that’s easy to forget; unlike other bathroom fittings, shower trays and bathtubs have a lot of pressure applied to them every day, so if they aren’t sealed with a flexible sealant you run the risk of cracks.

    With your preparations complete and the masking tape in place, use the instructions below as a handy reminder of the steps to follow for a professional finish.

    If you’re new to sealing, you can also pick up some more tips by watching Dunlop’s video on how to waterproof a shower, wet room or bathroom.

    Step 1: Get the applicator ready

    Open the applicator and cut open the tube according to the amount of silicone you need for the width of the line. If in doubt, start with a small cut and work from there.

    Step 2: Begin the application

    With the tube cut open at the end and the applicator screwed back together, start applying the silicone. Run the tip of the applicator along the space between the strips of masking tape, applying gentle, steady pressure to the nozzle and keeping the supply of silicone even.

    This will probably be second nature to you by now, but if you’re inexperienced at sealing, you can always test out the applicator on a piece of scrap first to make sure you’re familiar with it. You should also have a piece of cardboard to hand as you’re carrying out the application to use as a place to rest the applicator without marking the floor.

    Step 3: Apply the second layer

    If you’re applying a second layer of silicone, use your finger to push down on the first layer of silicone so that it’s properly filling all the gaps it should. Leave the masking tape in place and apply a second layer, using the same slow and steady technique as the first time.

    Step 4: Smooth the surface

    This is where you’ll need your silicone smoother, if you have one. You can also use your finger if you prefer. Moisten the smoother or your finger and then run it evenly along the line of silicone so you end up with a neat, concave join. Every few inches you should stop to wipe off excess silicone from the tool or your hand. Then rinse and repeat.

    Step 5: Carry out the final checks

    Now it’s time to take the masking tape off and assess the finished work. It might look smooth and even, in which case you just need to wait for it to set. If not, just smooth down any errant uneven areas you might have missed the first time.

  • 3. How to seal a basin or toilet

    This is business as usual for you; most of the steps involved in sealing a basin are very similar to those involved in sealing other fitted bathroom furniture. You’ll need to seal the space between the basin and the wall, as well as the space between the base of the sink and the floor.

    Of course, make sure any surface you’re sealing is dry, clean and free of soap residue, as this can affect the sealant. If you’re re-sealing a basin that has previously been in use, be sure to clean it very thoroughly before you begin, as it’s likely to have invisible soap remnants on it.

    With toilets, you’ll be sealing both the gap between the cistern and the wall and the area around the base.


  • How do I seal a bathtub?

    The process for sealing a bathtub or shower is very similar to the process for sealing any other item of fitted bathroom furniture. However, there’s one obvious difference: the need to use a flexible sealant on bathtubs and showers so that it stands up to pressure without cracking.

  • How do I seal a toilet?

    With a toilet, cracks should be less of an issue, so you can use a wider range of sealants. You’ll already know the key areas to seal: where the cistern meets the wall, and around the base of the toilet.