Detecting and Repairing Leaking Showers

By Chris Williams, WetWorks Bathrooms. November 2013

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Leaking Showers! It must be the most common problem associated with the housing industry. I have been renovating and repairing bathrooms for 13 years and have come across literally hundreds of people who have had leaking showers. Some of the renovations I have done have shown that the shower was leaking unbeknown to the home owner. In fact, I can't remember very many demolitions I have done and not found the shower to be leaking in some way. A leaking shower is generally the catalyst for a renovation but I have also come across homes that are only a year or two old that have leaking showers and need to be repaired. Some people just can't afford a renovation on a bathroom that really does need it and just want to stop the leak before it causes even more damage to adjacent rooms.

It isn't cheap to repair a leaking shower properly, so one needs to ensure that whatever method of repair you choose is the correct one for your type of leak. That sounds simple but a shower can leak from several different sources and sometimes even a phantom leak can put you off the scent. I once fixed a leak for a lady who had the whole shower ripped out and replaced by others and it still had a leak. The leak was actually a very simple fix that was overlooked. I will cover that shortly. Also, a teacher I had years ago at the MBA told of a similar story and it was later found that the water was coming from a leaking skylight. A leaking refrigerators ice maker caused me some worry once. The water travelled from behind the fridge under the wall into the hall, under the floating floor across the hall and came to the surface just outside the bathroom a few months after the renovation. It is very important to know where the water is coming from before you rip into it.


Who's going to pay is the question I hear a lot. It’s a common misconception that a leaking shower will be covered by insurance. Not always, but some leaks are covered. I am certainly not any kind of insurance expert but most of the policies I have discussed with clients all seem to say pretty much the same thing. Usually they say, if a pipe leaks, it is covered but once the water leaves the shower rose it is your responsibility until it enters the floor waste. I have personally only ever encountered 3 instance of water damage from leaking pipes behind the wall sheets in the shower. All the others have been leaks from screens, hobs and membranes. One of the exception of leaking pipes was the shower I mentioned in the previous paragraph about the lady who replaced the entire shower and it was found to be a leaking pipe. She had a handyman replace the shower head some months before and he had not used enough sealing tape on the threaded connection at the wall and a fine water jet was leaking back into the wall and took some months to build up and start soaking into the carpet in the adjacent room. I have no idea of how she got on financially with that one. The other two were never detected as leaks but found after demolition during full bathroom renovations. More details of these below.

Shower screens can leak. Water can run down the glass into the aluminium frame, travel a bit and then come out usually at the corner near the tiles. To check for this kind of leak make sure it is very dry before you start. Have one person in the shower with a hand shower spraying the glass and another person outside looking for leaks. Use lots of tissues and keep wiping everywhere and looking at the tissues. You will see the tissue get wet before you will notice water building up in any one spot. A common mistake I see here is someone seals up the inside of the screen to the hob or floor. The screen should only have silicone on the outside allowing any water build up inside the frame to escape back into the shower. If you locate a leak clean the area until it is spotless, let it dry out and use a Neutral cure, antibacterial silicone to seal it up.

Shower hobs are a major cause of problems. Rarely have I seen one done correctly. This could be because when done correctly they don’t leak so I never see them or it could be just that they never get built properly in the first place. Whatever the case, nearly everyone I see is the cause of a problem. Never have I built a hob for a shower and I never will. They are trouble.

The main problem with them is that people put the shower screen on the wrong side of the hob. The screen should sit flush with the inside edge of the hob so water running down the glass continues down past the hob to the floor. I have not seen to many like this, mostly, they all sit on the outside edge (see Fig A) so you have a little shelf on the inside of the shower. Water lands directly on top of the hob and also runs down the glass forcing itself into the grout joins on top of the hob. Once it gets through the grout, even if you have a perfect waterproof membrane, the water is now on top of the hob under the tiles and runs either back into the shower if you’re lucky or it runs outside the hob into the bathroom behind the tiles. It can then soak into the floor, back up through the grout and onto the floor or it could run around the outside of the hob until it gets to the door jamb or vanity and soaks into those. Hobs also create an excessive amount of internal corners. This is where concentrations of water also get forced into and eventually will find a way through.

Timber floors don't last long when wet
Fig A. Classic water leaking over hob onto the floor under the tiles. A mother fell through while brushing her daughters hair. Lucklily, he only fell 600mm or so. This was the first sign they had a problem.

If you have a hob as described above some of the things you can do are: seal all internal comers, dig out the grout on top of the hob and seal with silicone. Look for ways that water falling down onto it can force its way through. Make sure all tiles are clean first or your silicone won’t stick. A new screen sitting on the inside of the hob may work but you have just reduced the size of your shower and invested money in a new screen that "Might" fix the problem. The Best way to address these problems is to get rid of the hob and retile the whole base. You may be able to re-use the same screen as detailed later.

Taps and shower heads and other penetrations in the shower can leak. The BCA (Building code of Australia) states Taps should be sealed. It's not often I see them sealed. As part of my renovations I always seal up to the taps, mixers and shower outlets and apply a waterproof membrane onto the tap body/pipe outlet.(19BP). In some cases where the tap spindle is recessed into the wall the best you can do is seal them with silicone after the new spindles are installed. This is what would need to be done to an existing shower. Remove the shower head, tap handles and covers (Mixer handle and cover plate if mixers) and seal any gaps with silicone. If you need to change the washer (Valve) in the future you can cut it out with a knife and re-seal it after the new valve is installed. Mixers can be serviced from the very front so sealing these up well is not a problem later.

Fig B.The different stages of a mixer being sealed.

All shower heads are now are restricted to at maximum flow of 9 liters per minute. This puts extra pressure on the static pipes from the valve to threaded join at the wall. You can also do a pressure test on this static section of pipe. Remove the shower head. seal a bung onto the 1/2 inch threaded pipe ($2 from Bunnings) and turn on the water. If there is a leak in the pipe between the valve and the outlet you may hear it. Turn the water off and wait a few minutes. Release the bung and it should sound like you cracked a beer. If you don’t hear that "Pssst" sound, go to the fridge and crack an actual beer then call a plumber and check your insurance policy. You may be covered.
As mentioned earlier,I have seen 2 separate occasions where the person who installed the wall sheets in the bathroom put a nail through this static pipe. It has no pressure at the time so no alarm is raised. The pipe is never under full mains pressure when the shower is running so the leak is small, possibly just a drip. Both times it was on a timber floor home and the water just went under the house and no one ever noticed it. The rotten wall and floor frames still needed repairs.
The trick here if you are re-sheeting is to keep a bung on the outlet and keep the cold water tap open so the pipe is under full pressure while nailing. If a nail hits it you will know it.
If you are not 100% confident with any of the above get a plumber to come and check it. He will also have a pressure gauge he can attach for a more accurate test.

Waterproof membranes are the last line of defence to water leaking. Tiles and grout are not waterproof as described above. Generally a tiled shower floor will have a fall to the waste (drain) by means of sand and cement screed. This screed is porous and lets water pretty much travel straight through it. This is where the membrane should stop the water. Unfortunately it does not always work the way we want. Modern membranes generally fail due to incorrect installation procedures. Without turning this into a waterproofing lesson there needs to be consideration for things like house movement, floor and wall frame shrinkage and drying times for single part liquid applied types and how the water can get out and not just sit there for years and stink. (leak control flanges etc).
Back in the seventies and early eighties a Galvenised tray was sometimes installed as the waterproof barrier. These, over time rust out but did have a fairly good service life all thing considered.
Rusted galvenised shower tray
Fig B, Rusted galvenised shower tray after 35 years of duty.

If you have checked the above scenarios to eliminate them from the list and you still have a leak, then this leaves you with the possibility that the membrane has failed. Here’s how you check it.
Ensure the shower is dry and hasn't been used for 24 hours. Get some glad wrap, fold it over a few times and cover the waste. (drain) Fold a face washer and place it on the glad wrap and put some weight on it that wont float to help seal the waste up.
Now fill the shower floor with water from another source. i.e. The garden hose. This will eliminate the plumbing from the list of suspects. Fill it up to around half way up the hob and wait. Keep checking the adjacent rooms where you suspect water is going and see if you can locate any leaks. If you have carpet in the adjacent room get a set of pliars and grab the carpet near the wall and lift. It should come away from the smoothedge (strip of wood with little nails facing up) and you can then roll the underfelt back and check the floor. If the water level drops and you can't find a leak go under the house if you have a timber floor and look for water leaks. At this stage you should get water somewhere. If not your gladwrap seal might be leaking, try to reseal it with a heavier weight. If you have a more recently built shower you could have a leak control flange under the tiles and it could be going down there. This makes thing a little harder to check because the water could be soaking through the tiles and screed and soaking under the waist and into the drain pipe. (This is what it is designed to do) if you keep losing water and it’s not coming out any where it is more than likely going down the leak control or waste.
If the water level stays that way for an hour or so and you can't find any leaks, your membrane is possibly OK so you need to go back and try some of the earlier checks.
If your membrane is leaking the best way to repair it is to remove the screen and tiles, apply a new membrane and re-tile, re-fit screen.

Fixing leaks without removing tiles in my opinion is hit and miss and at best, not a permanent repair. I have heard of people having success (for how long?) with this method but I have also repaired plenty of showers that have had it done and failed soon after. Some clients say they got them back one or more times as a warranty call but just came to the realisation a more permanent repair is required before the damage gets worse.
Some have water detection meters that simply detect the presence of moisture to make it look all scientific but you as the home owner know your shower is leaking because your carpet is wet and you called them. Do they really need a moister meter to tell you your shower that gets wet every day is actually wet?
What they do is use an epoxy caulking and caulk up all the internal corners in the shower. Some patch the grout with epoxy grout as well. Epoxy is a terrific product and sticks to anything but has not flexibility. This can be successful so long as your house doesn't move, however the fact is all houses move during different times of the year. The  BCA states "All internal corners in wet areas where 2 different surfaces meet shall be caulked with a flexible sealant". For a temporary repair that will be better that epoxy you could try cleaning all the internal corners, scratch as much loose grout out as you can, even use a fine grinder to cut the grout without going to deep and damaging the membrane further. Then re-grout with a quality grout or you could even use silicone to fill every join. Leave it to dry. Clean again and apply a good bead of silicone to all the internal corners. (Read the section on patching hobs also). This will at least flex with your house and could buy you some time to save the money and get someone to repair it properly. I suggested this to a young couple who just purchased their home and they tried it on their bathroom that was looking a bit tired with great success. They called me back after a couple of years and I renovated the entire bathroom.

Ripping into it and removing the tiles and hob is required if all of the above prove ineffective. One further warning to note. If your home was built before 1985 you may have asbestos wall sheets. Have a read about Asbestos Here. If you have asbestos wall sheets then it is my opinion that you now need to do a full renovation because the only way you can address the asbestos is by removing all of it. You may find a tradsman who is not informed about asbestos (there are many) to do the repair but you will then place all of the occupants of your home and the tradesman at risk.
I will run through the process of repairing a shower base with some pictures. If you are handy and, have some basic tools you may do some or all of the steps your self. If not, then this is what you you should expect to get when you hand over a wad of money. Any good ceramic tiler should be able to do this for you but I will give you the basic steps to make sure you are getting what you pay for. Make sure you don't get someone who will just remove the screen, waterproof over the tiles. Then lay more tiles over the tiles. I have seen it done.
Fig. 1, Remove the screen carefully if you plan to re-use it. The screen on this job was made wrong but that helps when you want to re-use it. It is actuall the same size as the outside of the hob (I didn't get a photo until after the screen was removed) so providing it is high enough it can be re-installed closer to the floor later.
Fig. 2, The lower 2 rows of tiles need to be removed wall sheets need to cut leaving some sheet to apply the membrane to cover the join. Remove the hob and floor tiles.
Fig. 3, shows the timber frame starting to rot.
Fig. 1Fig. 2Fig. 3

Fig. 4, shows more rot further in. This will need to have timber blocks inserted to give the wall sheets something to fix to.
Fig .5, shows the vanity that soaked up some water. It was installed wrong also (below floor level)
Fig. 6, New wall sheets.
Fig. 4 Fig. 5Fig.6

Fig. 7 Aluminium angle on the floor the same colour as screen. Waterproofing extends into the waste pipe and up the angle and walls. The waste allows water to go around it and into the pipe.
Fig. 8 Screed, floor and wall tiles. White was a close match and kept it on the floor also as the tiles are unavailable after 20 years. The aluminium angle is a few mm higher than the floor tiles
Fig.9 Screen installed and a silicone bead seal the screen to the floor angle.
Fig. 7 Fig. 8 Fig. 9