Step 1. Mark out the area to waterproof around the shower
Measure up your wall and mark out where you will be waterproofing. Then mask those lines off with masking tape. A good rule of thumb is to extend your waterproofing 100mm above your water outlet and 100mm wider than the edges of your shower. But check your local council regulations to make sure what is required.
Step 2. Prepare to waterproof the shower
Use a brush to paint primer onto the area you want to waterproof. Use a generous amount on every surface. While you are waiting for the primer to dry, measure the edges, corners and internal joints that need to be waterproofed. Now cut lengths of the reinforcing membrane to cover these areas.
Step 3. Waterproof the shower walls
Paint a coat of waterproofing where your reinforcing membrane will be installed. Then put the membrane on the still wet area. Now apply another coat over the top, flattening the membrane with your brush as you go. To make it easier when putting membrane into recessed corners, cut a nick that lets it split across the different surfaces. Once the membrane is installed, use horizontal strokes to paint a first coat of waterproofing across the walls.
Step 4. Waterproof the shower floor
Install reinforcing membrane where the floor joins the walls and around the drain. Once again, paint the area, then put the membrane down and give it a second coat to flatten it. When your membrane is installed, waterproof the rest of the floor. Once the first coat has dried, give the whole shower cavity a second coat, this time using vertical strokes instead of horizontal ones on the walls.