Installing a new shower tray needn’t be very difficult provided you take the time to plan things carefully. The normal types of tray available are either low profile or adjustable height and installation is different for each. Adjustable height trays have space between the tray and the floor which gives access and space for the trap and waste installation. Low profile trays, however, are bedded directly on the floor and provision for the waste can be a little trickier.
Unpack the tray and other components and check it’s in good condition. Manufacturers will not accept claims for scratches and the like if the tray has already been fitted. They usually come with a protective plastic and this should be left in place for now.
Adjustable Height Shower Tray
Position the tray on the floor and adjust the tray so that it sits at the correct height. If the tray has a tiling upstand which needs to be recessed into the wall, mark around the top edge. Remove the tray and cut the recess in the plaster work to the recommended depth. Temporarily assemble the waste trap on the shower tray and reposition the shower tray checking that it sits squarely to the wall and that the recess isn’t interfering with the height adjustment.
Identify the most suitable route for the waste pipe. You will need to allow an appropriate fall on this so that the waste drains away properly. Assemble the waste pipe from the trap outlet back to the connection on your waste plumbing system, making sure that you give adequate support along its length with brackets so that it cannot sag at any point.
Remove the tray to make things easier, and assemble the waste outlet and trap in accordance with the manufacturer’s details. Then, reposition the shower tray and make any final adjustments to the height. The inside base of the shower tray will have been cast so that the surface falls towards the waste outlet. You therefore need to ensure that the shower tray is perfectly level. Use a spirit level to check in all directions. The base should be completely supported by all the legs so that it doesn’t rock. Secure the tray in position, again following the manufacturer’s details for this.
Connect the new waste to the trap outlet and ensure there are no leaks. You can easily do this with a hose from a nearby tap or use a watering can.
Low Profile Shower Tray
Low profile trays, as mentioned earlier, require a bit more work and planning to get the waste correctly fitted as there is no space between tray and floor. Place the tray in position and mark the perimeter. Remove the tray and replace floorboards in this area with a section of 18mm ply to fully support it. Loose fix the ply in position so that it can easily be removed later.
You should also make an access point on the floor next to the tray so that you can reach below to assemble the waste. This access point also allows for maintenance as well. Position the tray again and mark the waste outlet on the ply.
Cut a suitably sized hole through the ply and temporarily assemble the waste. Identify the most suitable route for the waste pipe. You will need to allow an appropriate fall on this so that the waste drains away properly. Assemble the waste pipe from the trap outlet back to the connection on your waste plumbing system, making sure that you give adequate support along its length with brackets so that it cannot sag at any point.
With the waste pipework all set up ready, remove the tray again. Make sure the ply is fully screwed down and that it is perfectly level. There is no option for adjustment on this type of shower tray so check carefully. Bed the tray using silicone or tile adhesive. This should be a complete bed rather than just using dabs of adhesive as the base must be fully supported.
Once the shower tray has been fixed in position, connect up the trap and waste following the manufacturer’s details.
Tiling and Sealing Around the Shower Tray
Tiling around a shower should always be done after installation so that a good seal can be created. Tiles should stop short of the tray by about 3mm allowing an expansion joint. Finally, apply a suitable shower sealant around the perimeter. To get a professional finish, tape can be used on either side of the joint. Apply the silicone and smooth with a wet finger or silicone shaping tool. Carefully remove the tape and allow the silicone to cure.
Shower Tray Plinth
If it is not possible to create a suitable fall on the waste pipe you may consider mounting a low profile tray on a timber plinth. Lay 75 x 100 mm joists across the area at 300 mm centres and fix an 18mm ply top to create the plinth. Give thought to which direction is most suitable for the joists so that you have the easiest access to the waste and plumbing beneath the plywood.
Common Shower Tray Problems
Shower trays can crack or split.
This is usually as a result of inadequate or uneven support. Make sure when installing that you follow the installation guide to ensure that the tray is properly supported across its base and that it cannot rock.
Leaking around base.
This may be caused by movement in the base. It can also be caused by poor application of the sealant. If so, remove the sealant and redo it taking care to ensure that the joint is clean and free from debris and that the sealant fills the void between tray and tiles.
Pooling of water in the shower.
This is caused by the tray not being installed level. The tray will have been made with a fall on the internal surface so that water will drain correctly to the waste outlet. Reinstalling so that the tray is perfectly level will solve this problem.
Creaking shower tray.
This applies particularly to acrylic height-adjustable shower trays. Small amounts of movement in the base can cause it to creak. Remove the side panels and establish where the support is inadequate. If the legs are a bit flimsy, you can add to the support using timbers between the floor and the tray.