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A person using a roller to apply waterproofing agent on a wall up to a masking tape line

Overview

Water leaking into your floor and wall spaces can rot structural timbers and cause damage. We'll show you the simple steps it takes to waterproof a bathroom floor without the mess.

Steps

1Clean the floor

Before you start waterproofing it's important that the floor is clean. Clear any dust and dirt away with a dustpan and broom.

A person sweeping an untiled bathroom floor

2Apply the primer

The easy way to apply your primer is to pour it into a bucket or roller tray first. Then using a paint roller, start in the back corner and work your way around the walls to a height of about 20cm. Then apply the primer to the whole bathroom floor.
A person using a paint roller to apply primer along the bottom of a bathroom wall

3Silicone the gaps

After the primer has dried, silicone seal all of the gaps between the floor and the wall and anywhere you find gaps in the floor. Use a paint scraper to remove any excess silicone. Then let the silicone dry for 24 hours before you start waterproofing. 

A person applying silicone between the floor and the wall in a bathroom

4Apply masking tape to the wall

Apply masking tape around the wall to the level you want to make waterproof. In our case, we're masking to the height of where the primer was applied. If you want to waterproof to the shower recess, your masking tape needs to be at a height of 1.8m. 

A person applying masking tape along a line drawn on a bathroom wall

5Apply the waterproofing agent

Start at the back corner of the bathroom. Use a roller to apply the waterproofing agent on the wall to the height of the masking tape. Then apply it around the width of the paint roller where the wall meets the floor.

A person using a roller to apply waterproofing agent on a wall up to a masking tape line

6Apply the waterproof membrane to joints

Cut the waterproof membrane into lengths of the bathroom walls. Lay the membrane down so that half is on the wall and the other half on the bathroom floor covering the crack. To stick the membrane down, use either a paint roller or brush to paint over it with the waterproofing agent. Repeat this until all of the gaps on the floor are covered with membrane and painted over. 

A person using scissors to cut a roll of waterproof membrane

7Waterproof the whole floor

After you have covered all of the membrane on the walls and bathroom floor with the waterproofing agent, paint the rest of the floor. Then leave it to dry for 24 hours.

A person applying waterproofing to a bathroom floor with a roller

8Apply the last coat of waterproofing agent

After letting the waterproofing agent dry, apply a final coat of waterproofing to the walls and bathroom floor with a brush or roller. You'll need to let this second coat dry another 24 hours before it's ready.
A person applying waterproofing to a bathroom floor with a brush

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Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. 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 or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.