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How to install a shower base

A pencil being used to mark cutting lines on a wall frame to make room for a shower base

Overview

Installing an acrylic shower base is easier than you think. With a little know how, you can do it yourself. In just a few steps we'll show you how to prepare the floor, mix the cement and lay down the base.  

Steps

1Measure the hole in the floor

Lay the shower base on the floor, where it'll be installed and mark its outline. Measure the width and length of the sump on the back of your shower base and add an extra 20mm so that there's some room for the sump to move but also so that the base still fits snugly into the floor. Measure the distance of the sump from the sides of the shower base. Transfer the sump measurements in from the side and use your spirit level to mark out the square where the hole will be cut for the sump to fit into.
Measuring the width and length of a shower sump along a floor sheet, along with a spirit level used to align the sump

2Cut the hole in the floor

Drill holes in the corners of the square you're cutting out for the sump to fit into. This'll make it easier for you to cut out. Put on your safety glasses, gloves and ear muffs and use the angle grinder to cut out the square in the fibre cement board. If you need to, use a hammer and chisel to help you remove the fibre cement board. With your battery powered saw, cut the next layer of flooring. You may need to use a handsaw to complete the cuts to the corners. Lift this piece of flooring out. You may also need to use the handsaw to cut any under-floor insulation that might be there.

A hole being drilled into the floor sheet to make room for a shower sump

3Cut out the recesses for the shower base

Lay the shower base on the floor and outline its height on all of the wood that it leans up against. Remove the shower base. The pencil mark on the wood is the top of the recess that the shower base will fit snugly into. Use a hammer and chisel or a handsaw to cut away the wood to make 10mm recesses for the shower base. You'll also need to make a 10mm recess in the timbers running across the length and width of the shower base. Do this by marking out 10mm in from the edge and use a hammer and chisel to cut the wood. Wear gloves when you mark this wood to protect against splinters.

A pencil being used to mark cutting lines on a wall frame to make room for a shower base

4Check that the floor is level

The next step is to check how level your floor is. This is important because it will show you which areas, if any, might need extra cement to level the floor. Use your spirit level to check the levels across the length and width of the floor.
A closeup of the bubble in a spirit level, used to ensure the floor is level

5Mix your cement

To make your cement, mix three parts of brickies sand with one part mortar in a wheelbarrow. Slowly add water to the mixture and combine them using your shovel, so that it's not too thick and not too runny. Continue mixing until the concrete has a uniform consistency and texture and there are no pockets of dry material.

A wheelbarrow holding a shovel, a bag of concrete and a bag of bricklayer's sand

6Lay the concrete base

Use your shovel to lay the concrete base on to the floor, so that it will cover all of the shower base, which will give it a solid foundation. If you need to, add extra concrete in the areas where it is needed so that the shower base is level when you put it into place.

Concrete being shovelled onto the floor where a shower base will be laid

7Put the shower base in place

Lay the shower base on top of the concrete and wriggle it into place and sit it snugly in the recesses you cut out. Once it's in place use your spirit level to make sure its level. If it isn't move it around until it is. Use your shovel to clean up all of the excess cement around the edges of your shower base.

A shower base being laid into place on wet concrete

8Insert the nogs to hold the shower lining

To make sure the lining of the shower is held firmly in place, you need to insert nogs between the vertical studs. Measure the distance between the studs and using your electric saw and saw stool to cut the nogs to size. Place the nogs just above the shower base and fix them all into place using a nail gun.
Nogs being fitted to the inside of a wall frame and nailed down with a nail gun
Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint.