There are 2 main reasons to raise a shower base. The first is to accommodate the waste pipe and trap. The second is to create a more modern look with a plinth and step. It is not hard to raise the level of the shower base, but remember not to block the drain weep holes.
Step 1 - Mark Out the Shower Tray
Place the shower tray in its position and mark around it with the pencil, also marking the position of the waste outlet. Remove the tray. Place the pipe over the drain mark.
Step 2 - Place a PVC Pipe Over the Waste
Make sure the floor is level. Lay the bricks in a wall along the marked line of the layout, making a dam on your shower floor. Build it up to the height you require. Place the pipe over the marked hole, making sure the pipe is a little longer then necessary. It can be cut down to size later.
Step 3 - Make Sure There Is Fall
Allow fall in the PVC pipe to allow for fast drainage. Build-up the shower more to ensure a suitable fall if it is too shallow with the base sitting on the bricks.
Step 4 - Check the Pipe
While the mortar is drying, double check that the pipe will attach to the waste drain in the tray. Don't connect it yet.
Step 5 - Fill the Dam
Fill the dam high enough with river sand that it will support the shower base. Make sure you pile crushed tile or gravel around the PVC pipe so sand doesn't block the weep holes.
Push the tray into the sand so that the edges touch the sand on all sides. Remove or add sand to get it level. The sand must feel solid with no give so it has no movement when the shower is used. When you have everything right, connect the pipe to the waste outlet. Make sure there is no sand in the pipe before you attach it.
Step 6 - Tile the Bricks
If you don't want to leave the bricks as they are, tile the sides and top for a neat finish. Coat the grout with a sealant. Leave to dry. If you prefer the look of the bricks, you must seal the mortar between the bricks.
TIP: Grout usually only takes about 30 minutes to set, but doesn't fully cure for 72 hours. Do not coat the grout with sealant until it's finally cured.
Step 7: Apply Sealant
Apply silicone sealant around the edges of the shower tray to prevent water running under the tray. Don't use the shower until the sealant is dry.
If you prefer, you can build the "dam" with boards instead of bricks. You can fill this dam with concrete if it is not too high, instead of sand, to make a more solid shower base. Make sure the base and plumbing is done properly as it would be difficult to pull up again.