If you've got a large enough bathroom, a separate shower stall can be a convenient addition to your bathroom's function.  You'll need to install a watertight enclosure that's fully sealed around the drainage tray, to ensure no water sprays out into the room.  When preparing your site, you'll need to route your drainage outlet and water supply pipes to the new position.  These guidelines presume you are installing your shower stall onto a hardwood subfloor.  Having your shower stall slightly higher than floor level makes it easier to run the drainage pipe beneath it.

To make the best use of space, shower stalls are generally fitted in a corner, which means you'll have two tiled walls and two screen walls.  The shape of the cubicle varies according to the design you choose, but the basic principles for fitting a shower stall are the same regardless of the shape.

Put your shower tray on the floor where it's going to go, and draw round the outside.  Then cut out a section of the subfloor through which you will install the drainage pipes.  It's important to leave room to add an access hatch on the outside edge of the tray.  In the hole you've cut out, nail wooden batten under the edges and cut out a piece of hardboard the same size as the hole to sit on top of the batten. 

Using 4 parts building sand to 1 part cement, mix up some mortar and spread it on the floor where your tray is going to be fixed.  Put your tray in position on the mortar and use a spirit level to make sure it's completely level, from all angles.  This may take a bit of time.

Once your tray's in place, in the hole that you made beneath you'll need to connect the trap to the waste outlet and join it up to the waste outlet pipe.  You're then ready to fit the cubicle.  There are lots of different styles of shower stall, but here we describe how to install one with a hinged design.

The shower enclosure sections need to be fixed to the walls using special channels.  Use a spirit level to position the channels vertically on the wall at each corner and fix them to the wall using the fixings supplied.  Place the section of screen that's not going to open into the relevant wall channel, before slotting the opening section into place.  It makes the job easier if you enlist the help of another person at this point, to hold the sections in place so they meet at the appropriate point in the corner.

You can then drill holes through the wall channels into the frame of the shower stall sections and use self-tapping screws to secure them.  Make sure you use drill bits that make pilot holes smaller than the screws you're using.  You can then attach the door handle, then finally seal all the joints and internal edges using silicone sealant.  Do not rush this stage, as if you don't do this properly your shower stall won't be watertight!