Sealing A Bath Permanently

There is a little more to sealing a bath permanently than simply cutting the end off the nozzle of your silicone and getting stuck in.

Sure you could try this approach but there is a very good chance you will be repeating the exercise in the near future.

If you are having to re-seal around your bath then there is obviously a problem that has caused it. This problem needs to be addressed to ensure it does not re-occur. So first we will look at what causes the problem in the first place.

beige bathroom wall panels - Sealing A Bath Permanently

What Causes Silicone Sealant To Fail?

There are 3 main causes. Any one of them could be the cause or any combination of them as well. They are:

  • movement of the bath pulling the seal away
  • poor preparation preventing the seal adhering to the surfaces
  • poor quality silicone

The second two problems are easily resolved.

Clean and dry the areas to be sealed very thoroughly. Baths can have mould release agent on the surface from when they were manufactured which will prevent a good bond. Tiles can be dusty and wall panels can also have mould release agent on them.

Do not buy cheap silicone as it is a false economy. We recommend Dow Corning silicone as one of the best on the market.

Dealing with the first problem, movement,  is more involved.

There are two distinct approaches to sealing a bath permanently and eliminating movement. It depends on whether this is a new installation or fixing a problem with an existing bath. Let’s look at an existing bath first as this is the most common situation.

Preventing Movement For An Existing Bath

Most baths are made from acrylic these days. There are other materials but this is the most common. And it causes the most problems.

Acrylic sheet is slightly flexible so has to be reinforced with fibreglass. But even this combination is liable to flex when under load.

A full bath of water weighs a lot. Add in a human or two and it weighs even more. The bath can sink slightly or bend slightly when in use and this can pull the silicone seal away from the bath or wall.

One solution is to support the bath underneath the rim all the way around walls.

Remove the bath panel and measure up into the underside of the rim from the floor. Cut some wooden battens a few mm longer than the measured length. Reach under the bath with them and then wedge them into place around the back and end of the bath. While the panel is off you could also prop up the base-board of the bath with more timber or bricks. The less the bath moves the less chance of your silicone failing.

bath no support - Sealing A Bath Permanently

bath support - Sealing A Bath Permanently

Preventing Movement For An Existing Bath

The rim of a new bath should also be supported when you are installing it to prevent movement. There are several ways to achieve this.

You could grind a shallow channel around the wall and lip the rim of the bath into this channel. The bath can then be plastered into place to ensure it does not move at all.

If this is not feasible you could run a batten around the walls directly under the rim of the bath. This will require the wall to be relatively solid. If you have stud walls you need to attach the batten to the studs to ensure a solid fixing. If the walls are plasterboard only then the horizontal batten will need to be supported with vertical batten – similar to those described for an existing bath installation.

Before fitting the bath in place cover the sides of the rim with a good quality silicone so that nothing can get down between the bath and the wall.

Applying The Sealant

Having made sure you have thoroughly cleaned the area to be sealed and purchased goody quality sealant you are now ready to proceed.

The easiest way to get a neat finish if you are not an expert is to stick masking tape to the bath and the wall. Apply the sealant a small section at a time – it is very easy to blend each section into the next when the sealant is still wet. Work quickly as you need to remove the tape before the silicone starts curing. Have a bucket or old towel ready for the tape as it will be covered in wet silicone.

Use a caulking tool or wet finger to smooth the sealant into place and blend one section into the next.

Wait at least 12 hours before using the bath – preferably longer, to ensure the sealant is fully cured.

Further Information

The only other problem that can occur is silicone turning mouldy due to grout.

If there are mould spots in your silicone it means moisture has got behind the sealant and this is invariably down to grout. Not all grout is waterproof so moisture can pass into and through it and let water get trapped.

If this occurs remove the problem sealant, seal the grout with a grout sealer and then re-apply the silicone.

Alternatively you can panel over tiles with bathroom cladding eliminating the need for grout all together.

Sealing a bath permanently will be straightforward if you follow these steps.