10 Tips to a Leak-Free Shower

Following on from the question of sealing grout in a shower to prevent water ingress (see here), here are my top 10 tips for ensuring a leak free shower enclosure. Much of this also applies to showers installed over bath tubs too.

1. Construction – It all starts with the construction of the shower enclosure itself, if the foundations are not up to scratch then nothing else is going to matter very much. If you are lucky enough to have solid masonry walls and a concrete floor then you won’t have much to do here, save for checking there are no cracks or faults present. However, many of us, especially in the UK, will have first-floor showers on wooden structure floors with plaster-boarded, stud-partition walls. If that is you then you have a disaster just waiting to happen. My advice would be to take the seemingly drastic action of removing the plasterboard and replacing it with something more appropriate (point #2). While the boards are off, check and if necessary add bracing to the stud wall to sure up the frame. Also, at this stage you can check on the condition of any hidden plumbing. Same goes for the floor; one of the biggest reasons for failure in shower enclosures that I see is the floor moving away from the wall – or just flexing too much. This causes gaps to open up and no amount of ‘after the event’ silicone sealing is going to cure this. So do what ever you can to brace the floor; this can be adding more noggins to the joists, (which means getting access to them either from above or below). Sometimes just over-boarding is enough – the aim is to just eliminate, or reduce and deflection as much as possible.
2. Use a Tile-Backer Board, not plasterboard – Gypsum plasterboard sucks – literally. The problem for standard plasterboard is that it is absorbent and also, once it has got wet – it swells and is ruined. So if water gets through the tiling into the board, the board disintegrates and down come the tiles. Even if this does not happen straight away, it still lets water through and also allows mould and mildew to grow behind the tiles.Instead, use one of the many alternative tile backer-boards that are now so widely available. There are basically two types: Concrete board and light-weight extruded foam type boards. The Concrete ones are cheaper as a rule and have the advantage of being much more stable than plasterboard, in that water will not degrade them. However, they can be heavy and hard to handle, as such they are better suited in my opinion to floors (where they add strength) than to walls. The other type is usually composed of an extruded foam core, sandwiched between two outer layers of paper or cement and fibre coatings. This type of board (there are many on the market; Wedi, Hardi, Easybaord etc) are lightweight, strong and easy to cut and handle. They are waterproof and totally stable. Whilst they maybe not quite as strong as the concrete boards, they are more than adequate for walls. Replacing plasterboard with something like this will stabilise and contribute to the overall water-proofing of the enclosure. Both types of boards can be adhesive fixed to solid walls or can be screwed through into the joist and studs with special screws and washers. Screws should be placed at 300 mm (or 12”) centres wherever possible- especially into floor joist and noggins. Joints between these boards can be taped over with special fibre-scrim tapes and a suitable tile adhesive; specially reinforced neoprene flexible tapes can be used to join the floor to the wall and also vertical changes of plane. If you cannot get this type of board, then at least use a good quality marine-grade plywood (use at least 18 to 20 mm thick for flooring).
3. Build a solid base – So many people rely on 4 or 5 spindly legs under a bath tub or shower tray – not the most stable of methods in my opinion. I prefer to build a proper base out of timber, but make it solid, with a plywood top, not just two bits of 4×4” sawn timber, laid under the tray as in so many that I have seen over the years. This works great on solid floors, but what is the point of a solid base if it is on a flexible timber one? If the floor moves in relation to the walls, it won’t matter how solid the base is. (I see this a lot in new builds, once the timber in the structure dries out, usually after the customer moves in and starts using the central heating, the wood shrinks and moves, sometimes it just settles and pulls down away from the wall). So….
4. Fix the base to the WALL, not the floor: a few big screws or bolts sideways through the timbers of the base, into stud frame of the wall and the base is going nowhere, whatever the floor decides to do. For bath tubs I just throw away the two little bent brackets that come with it and fix a 2×1” batten on the walls to the 2 or 3 sides that the bath tub goes up against. This way the weight of the tub is taken by the shoulders of the tub and is evenly distributed plus it stops the edges of plastic/acrylic bath tubs from flexing away from the wall when people stand in them. Then just adjust the 5 metal feet down to add extra support. It also ensures a nice level bath tub! If the installation is an existing one and you cannot do the above, then at least investigate ways in which you may be able to sure up or strengthen the supports, your aim is to minimise movement and deflection – in other words to stabilize everything.
5. Use a solid tray – A no brainer this one – cheap plastic trays are a false economy. If they move and flex under foot then sooner or later something is going to give and there will be leaks. So spend a little more on a solid tray, it can be porcelain or resin-bonded, plastic filled with lightweight but strong foam – it does not matter, just get one that is not going to flex.
6. If using wet-room type specialist floor tray (to be tiled), then make sure floor joists are well braced against movement. There is no base involved here as you are basically tiling a specially prepared section of the floor – so all the more reason to make sure that there is no flexing or excessive movement in the floor before you start
7. Tanking – Tanking kits are now widely available from many companies, they are all slightly different, but in principle they do the same job. They can be liquid or liquid/fibre matting combinations but they all provide a seamless coating that spans the entire floor, from the outlet drain, (if using a wet-room type tray), or at lease overlapping the edge of the tray/bath slightly to right up the walls. This provides a completely water-proof ‘tank’ behind the tiles and for my money in this day an age should be considered a must. A properly tanked shower with a well built structure behind it will not leak, no matter what the tiling, grouting or sealing is like on top.
8. Silicone – Don’t forget to get a good quality, bathroom grade, silicone sealant or caulk. I often put a small neat bead of silicone between the tray and the wall BEFORE tiling. I then tile right down to the tray, leaving a neat small gap to the tray. This I then seal with a very small, discreet silicone bead. I prefer this as you can get a very neat finish, a small bead is less likely be picked at by people and it is less able to hold mould and mildew – plus it looks a heck of a lot better and more professional. This also eliminates the need to the plastic shower seal strips which are largely not as effective as people think in my opinion. Don’t forget to silicone the vertical ‘movement joint’ between any changes of plane in the wall tiling also (and that means in place of grout, not over it).
9. Adhesive – These days it is easy to get good adhesives that are highly water resistant have the added benefit of being a little flexible. So check with your supplier that your adhesive is up to the job, and that it is the right one for the type of sub-structure you have. Showers are easy to mess up and a pain to fix, so you might want to leave the tiling to a professional. If you are going to do it yourself – make sure you solid bed the tiles.
10. Grout – Same goes for grout, make sure to use a suitable grout, this will in all probability be a polymer modified powder grout – again, check with your supplier.
11. Sealers!  (11?, in a 10 point list?? – couldn’t resist – see previous post)

Follow these guides and you should have no problems: in other words, use suitable materials to build the enclosure, do all you can to brace the structure and eliminate movement and flexing, tank the walls before tiling and get the tiles installed professionally with the appropriate setting material and grout – happy, leak-free showering!

Copyright Ian Taylor and The Tile and Stone Blog.co.uk, 2013. See copyright notice above.