How to Waterproof Bathroom Floorboards With Varnish

Written by laurenkrotosky
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How to Waterproof Bathroom Floorboards With Varnish
A roller brush will help you apply varnish to floors. (paint roller image by Ana de Sousa from

Waterproofing wood floorboards is a crucial step in home maintenance, especially in a bathroom where moisture can cause mould to grow on your floor. You can use a simple urethane varnish over your treated floorboards to offer protection, and the clear varnish will ensure your wood stain still shows through. A few basic tools such as a paint roller and paint tray will help you finish the varnish application without having to employ a professional woodworker.

Skill level:

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Things you need

  • Sandpaper
  • Wood stain
  • Rags
  • Polyurethane varnish
  • Paint tray
  • Roller brush
  • Extension rod

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  1. 1

    Sand the floors. Sanding down floors removes rough patches and splinters and ensures an even application of the stain and varnish.

  2. 2

    Apply the wood stain to the floorboards with dust rags and let them dry. Apply a second coat if necessary and let them dry.

  3. 3

    Attach an extension rod to the end of a paint roller so you can hold it at staff length without bending over while applying the varnish.

  4. 4

    Pour a clear polyurethane varnish into a paint tray.

  5. 5

    Apply the varnish to the floor by turning the roller in the paint tray, then rolling it over the floor. Apply a thin, even coat of varnish to the entire bathroom floor and let it dry before walking on the boards.

Tips and warnings

  • Start applying the varnish at the far corner of the bathroom and work back toward the entrance so you don't paint yourself into a corner.

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