Leaking Shower - Causes And Solutions From The Bathroom Marquee (2024)

A leaking shower can be costly and damaging. So if you think yours is showing signs of a leak then you need to investigate and get to the root of the problem. This article is designed to help you identify and rectify problems with your shower cubicle.

There are 5 main areas where leaks can occur in a shower and each one has a different cause and a different solution.

We will look at each problem area one at a time and illustrate what lies behind the problems and what can be done to remedy the situation. Some are obvious but one or two will not be what you are expecting to hear!

The following diagram has the problem areas highlighted more or less in order of frequency. This order is based on years of working in the industry and having to deal with customers looking for solutions to their leaking showers.

Common Areas Where Leaks Are Found

1. joint between wall and shower tray
2. tiled walls
3. supply pipes to the shower valve
4. shower waste and pipework
5. leaks coming through the frame and glass

So with the problems listed lets get to grips with what causes them and what can be done to fix them.

1. Joint Between Shower Walls And Shower Tray

The joint between the shower tray and the walls is the most common area where leaks occur. But there can be several reasons why the shower leaks at this point.

Movement of the shower tray – if the shower tray moves slightly it can have two effects that cause problems: it will pull silicone sealant away from the surface; it will cause cracks in the grout of the bottom row of tiles.

The reasons that the shower tray moves are either
a) it is a badly made tray that allows it to flex when a load is applied or
b) the floorboards and joists underneath the tray are allowing movement or
c) both(a) and (b) are happening

Solution – for situation (a) is to support the tray underneath if access is possible to prevent it from flexing. If not the tiles will need to be covered with a panelling system to cover the grout and a second seal applied. Situation (b) is impossible to rectify with the shower in place so panelling over the tiles is the best solution.

Faulty Sealant – the usual reason that sealant fails is excessive movement of the shower tray but there can be other reasons. Good quality silicone will form a strong bond with the surface to which it is applied but cheap sealant has poorer adhesion which will cause it to de-bond and allow water to get behind it. If you can see mould in the sealant you have a problem and it needs correcting (see our article on why silicone turns mouldy). Poor preparation will also cause the silicone to fail. The surfaces need to be clean, dry and free of any soap residue. The more attention you pay to the preparation the longer the sealant will last.

Solution – remove faulty silicone with a razor-sharp knife (preferably a craft scalpel), clean the area thoroughly and wait for it to be bone-dry before applying a new bead of top quality silicone sealant, such as Dow Corning.

Faulty Shower Seal Trims – Sometimes a trim with a flexible lip is fitted when the tiles are being installed. In our experience, these can hide potential problems. You will still need to seal the tray to the wall behind these trims and where they meet in the corners. We have seen occasions where the rubber lip has been distorted due to excessive heat or been affected by strong cleaning chemicals rendering them useless. The big problem with these trims is that they are impossible to replace in-situ. They also cause problems when trying to remedy the situation as they protrude out from the wall.

Solution – cut out the faulty trim and replace it with a solid quadrant moulding and seal it into place on all sides. Or remove the trim, seal the void left by its removal with silicone and cover the whole wall with a waterproof shower wall panel system and seal again.

2. Tiled Walls

Surprisingly, a leaking shower can be caused by tiles – something you would assume to be waterproof. And leaks do not only occur down where the tiles meet the tray – they can happen anywhere in the shower.

The reason that this is a problem area is quite simple – grout. Standard powdered grout is not waterproof as it is slightly porous and allows moisture to be absorbed. If the tiles are fixed to plasterboard and the moisture gets through to it the problem escalates quickly as the board will soak up moisture and pull more moisture through.

Ideally, epoxy grout should be used in showers but this is very expensive and not that easy to apply. Other more waterproof versions of the familiar powdered grout are available but these should be used in conjunction with a grout sealer to ensure a long-lasting finish.

Powdered grout will not tolerate any movement at all. Expansion and contraction near hot water pipes can cause tiny cracks to appear which will let water get through. Tiling onto a plywood panel will cause similar issues as wood will expand at a different rate than the tiles putting the grout under strain.

Solutions – rake out faulty grout and re-apply a waterproof formulation. Seal the finished grout with a grout sealer. Or cover the tiles with a modern shower wall panel system to eliminate the problems instantly and permanently.

3. Supply Pipes

The pipes supplying your shower mixer valve or electric shower will be under pressure so if they are not installed correctly they can leak over time. As the trend these days is to bury all of the pipework to provide a neater finish any leaks can be hidden for a long time as the problem will be hidden behind the tiles. Things to look out for to check if your leaking shower is down to this issue will include discolouration of the grout around the shower valve area or tiles becoming loose.

Solution – if there is access to the pipework behind the wall (in an airing cupboard for example) make any alteration necessary to eliminate the leak. If access is not possible then it might be necessary to remove all of the tiles to gain access to the problem. You can then either make good (depending on how much damage has been caused) with shower wall panels or start from scratch and replace the whole cubicle.

4. Waste Pipes

There is no real pressure in this pipework. But it is attached to the shower tray via the shower waste so will be subject to movement if your tray is not rock-solid. This can lead to leaks over time. The waste pipe will run away from the shower to the soil pipe so leaks can occur anywhere along this line. This will be seen from staining on the ceiling below the shower (if the shower is upstairs) but this could also be the result of one of the other problems listed above.

Solution – if access to the pipe-work is possible adjust, seal or tighten any joints to eliminate the leak. If not, the whole shower will need to come out.

5. Leaking Through The Cubicle Frame Or Glass

This is another cause that does not seem to make sense – but it can, and does, happen.

The frames used to mount the glass panels are hollow and water can build up inside the frame and cause a leaking shower.

It is important that when you are sealing the inside of a shower cubicle that you do not seal around the bottom of the frame where it meets the tray – this is the area where any water inside the frame needs to run out into the tray harmlessly. You can seal vertically where the frame meets the wall and you can seal outside the enclosure where the frame meets the tray but not horizontally inside the enclosure.

If the inside of the enclosure has been sealed to the tray you will see water escaping through the frame/glass joint which will indicate that the frame is full of water.

Solution – remove any horizontal seal inside the cubicle where the enclosure meets the tray.

Less Common Problems That Cause A Leaking Shower

Tiling behind the shower tray – you should tile down onto the top of the shower tray not behind it.

Cracked shower tray – this is not very common but it can happen. It might be a hairline crack that is not highly visible and is disguised by the non-slip pattern.

Cracked tiles – usually visible and obvious but not that common

Seals around mixer / slider rails / soap dishes etc – anything that requires holes being drilled through the tiles or panels need to be sealed thoroughly with a good quality sealant.

Leaking Showers – Conclusion

It is unfortunate that many of the products used in showers can themselves be the cause of leaks. Movement is the biggest problem. And some products will not tolerate the slightest movement at all.

Timber floor construction and slightly flexible shower trays all prevent a shower from being 100% solid. So, are there any guaranteed solutions?

Shower pods are designed to be leak-free from the outset. There are several different design approaches – this article has more details on shower pods.

The other option is to eliminate the most common leaking site – the join between the tray and the wall. If you buy a shower tray with upstands ad use it in conjunction with shower wall panels you will ensure non of the most common leaks can occur.