How To Correctly Silicone Seal Your Bathroom

How To Correctly Silicone Seal Your Bathroom
February 23, 2018 Michael Hawkins

To properly silicone seal a bathroom is essential if you want to ensure you have a fully waterproofed area that doesn’t go rotten and mouldy quickly.

Where do I need to seal so I don’t get any leaks?

You must seal any joints between differing surfaces, with a water resistant sanitary silicone sealant when they’re located within wet areas, such as around baths, showers, shower screens and basins.

The main areas in a bathroom that require sealing are as follows:

  • Around a baths edge anywhere it butts up to a different surface
  • The exterior edges of a shower screen
  • Where a basin sits against the surface its fixed to
  • Boxing and flooring edges
  • Between cladding joins when contained within wet areas
  • Basin waste grates
  • Any area that will be susceptible to water splashes and water runoff

How do I apply silicone sealant?

Make sure you have a decent sealant gun as it will be essential in applying to the desired areas with ease.

Quick tip: Before applying the sealant, ensure the area is completely free of dust and is dry. This will allow the sealant to adhere to the surfaces properly. Skipping this step would result in improper adhesion, gaps and dust to embed in the sealant.

Simply apply a continuous small bead of sealant along the joint. Be careful not to apply too much as it can be difficult to remove while maintaining a smooth seal.

Important preparations

Make sure to fill the bath full with water before sealing around it. The reason for this is that through regular use of your bath there will be small amounts of movement, and this pushes and pulls on the seal.

Filling your bath with water during sealing up simulates this extra weight and movement. Applying the sealant during this time ensures it will not be pulled apart by any movement of the bath in the future.

When sealing up a shower enclosure make sure you only seal the outside of the enclosure and any joins recommended in the manufacturers instructions. The reason for this is that when water finds its way behind the profiles or underneath the screen it should have the freedom to flow back into the shower area.

Otherwise the water will become stagnant, resulting in bad smells. The water lying on the inside will degrade your sealant much faster than normal resulting in leaks and black mouldy sealant.

Smoothing off the seal

Now comes the hard part, smoothing the silicone into the joint and removing the excess. You should wet the tip of your forefinger and gently run along the joint with the tip. Be sure to maintain a consistent angle all the way.

You want to try and get the silicone as smooth and as consistent as possible. This is will prevent excess scum buildup and will allow water to run off of it smoothly, which will make the sealant last longer.

Wetting your finger before smoothing prevents the silicone from sticking to your finger too much, allowing you to create a smooth sealed joint without any spread.

Quick tip: Fill a spray bottle with soapy water and lightly spray the silicone before smoothing. The soap and the water will stop the silicone from sticking to your finger and spreading out too much onto the surfaces, allowing you to remove excess with ease.

Important tip: After application allow a full 24 hours for the silicone to fully cure before making use the area.

Are there any tools that I can use to help me?

There are also various silicone applying tools that are specially designed to provide a nice finish, available at your local DIY store or online. Most silicone removal tools also have a smoothing tip to help with proper application.

We highly recommend the Cramer 5-Fugi Kit, it comes with various sizes to help with most joint gaps.

Apply the same methods described above when using silicone smoothing tools. Lightly wet the area and the tool for smoothing and removing any excess after each use.

What type/colour of silicone should I use?

When it comes to buying the right silicone for your bathroom you want something that is suitable for very wet and damp environments.

Buying the best quality is essential. Even though it will tend to cost more than the average type, it is worth spending that little bit extra to ensure a higher quality, longer lasting seal. They also tend to be thicker, making them easier to apply.

Another reason spending good money on silicone is that removing old mouldy sealant is very tedious and time consuming. Not to mention the possible damage caused to the area while removing.

You must use a Sanitary silicone sealant. They are specifically designed to be more resistant to the large amounts of water and damp wet areas are subjected to.

Using non-sanitary sealants will result in the the seal turning black with mold very quickly.

You can also purchase various colours of silicone. The most commonly bought are white or clear. Coloured sanitary sealants are also available to use depending on what would match the required area.

How do I keep the silicone in good condition?

Sealants will deteriorate over time and eventually the silicone you’ve applied will start to go mouldy. How quickly this happens depends on how well the silicone has been applied to the area, and how well the area has been maintained.

Silicone goes black and mouldy due to the high humidity, warmth and dampness of the area.

When you wash yourself, shampoo, soap and dead skin cells end up lying on your silicone seals. This ends up providing a nice tasty meal for bacteria. Combined with the damp and humid conditions the bacteria and mildew will thrive.

Here are some quick tips to ensure a longer lifespan for your sealant:

  • After using the shower leave the enclosure doors open
  • Clear the area of standing water by wiping down the surrounding surfaces with a cloth or sponge
  • Don’t leave any damp shower cloths or sponges laying directly on the silicone seals
  • Keep it clean, when cleaning your bathroom don’t overlook the seals, give it a good wipe down
  • Provide good ventilation to the area, such as an extractor fan or openable window.
  • Apply the silicone as smoothly as possible, this prevent buildup and allow the water to run off


If you follow the above instructions and tips your silicone will last for a long time. You may even extend the average lifespan of the sealant.


Comment (1)

  1. Bob Clark 4 years ago

    Do you need to put silicone around shower fittings such as control blocks and jet outlets for brands like GROHE?

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