How to Waterproof Wood for Bathroom? (3 Methods)

You can waterproof bathroom wood to protect it from water damage, beautify it, and increase its durability.

To prep wood for waterproofing, clean the wood, remove the existing finish, and repair it.

To waterproof wood for bathroom, use Thompson’s water sealer, wood oil, or polyurethane.

What are The Benefits of Waterproofing Wood for the Bathroom?

Pros Of Using Waterproof Wood In Bathroom

The benefits of waterproofing bathroom wood include water damage protection, beautifying wood, and increasing durability.

  1. Water Damage Protection: A sealer creates a moisture-resistant layer (or barrier) over the surface and protects wood from moisture, water, scratches, and other elements. Since water can’t penetrate the surface, wood doesn’t rot and lasts longer.
  2. Beautifying Wood: Some sealer types create a glossy colorful or transparent finish over the wood and highlight the surface patterns and texture, making it look better.
  3. Durability: Wood sealers create a moisture-resistant layer that helps the wooden surface last longer.

How To Prep Wood for Waterproofing?

To prep wood for waterproofing, do the following things.

  1. Clean the Wood.
  2. Remove the Existing Finish.
  3. Repair it.

1. Clean The Wood

Clean the wood to remove dirt, dust, and debris that can prevent the sealer from adhering. If you don’t clean the wood, a transparent sealer will highlight the dirt and dust.

To clean the wood, use TSP or warm soapy water. Don’t use too much water as wood can absorb it.

2. Remove the Existing Finish

If the wooden surface is already sealed with another sealer, remove the existing finish. The existing sealer can prevent the new sealer from adhering properly and forming a protective layer (barrier).

To remove an existing wood sealer, do the following things.

  1. Use a solvent-based paint stripper and steel wool.
  2. Once the finish is removed, sand the surface with fine-grit sandpaper.
  3. Remove the paint stripper residue.

3. Repair it

If the wooden surface is cracked, damaged, or has holes, repair it with wood filler before applying a sealer coating.

How To Waterproof Wood For Bathroom?

To waterproof wood for bathroom, do the following things.

  1. Use Thompson’s Water Seal.
  2. Use Wood Oil.
  3. Use Polyurethane.

1. Use Thompson’s Water Seal

Use Thompson's Water Seal

Thompson’s water seal is a silicone-based transparent sealer that creates a moisture-resistant layer (barrier) and protects surfaces from moisture, water, and other elements.

Water sealers penetrate the wood pores and seal them from the inside, preventing the surface from absorbing water. The Thompson’s water sealer transparent finish will highlight the bare wood texture and patterns.

Here’s how to use it:

  1. Clean The Surface: Remove the dust and filth from the surface.
  2. Apply the Water Sealer: You can apply Thompson’s Water sealer with a sprayer, roller, or paintbrush.
  3. Allow the Coating to Dry: Thompson’s water sealer takes around two (2) hours to dry between coats.
  4. Apply Another Coating.

2. Use Wood Oil (Tung Oil)

Use Wood Oil (Tung Oil)

Wood oils are natural or synthetic oils used to enhance the wood’s appearance and protect it. To waterproof a bathroom wood, use Tung oil as it’s a natural oil that creates a moisture-resistant layer over the surface and protects it from water.

Tung oil also creates an amber-like finish that enhances the wood’s appearance by highlighting the surface patterns and texture.

Here is how to do it:

  1. Prep (clean) the surface.
  2. Thin the Tung oil with mineral spirits (only a small amount of mineral spirits is needed).
  3. Apply the first Tung Oil coat with a clean rag, bristled paintbrush, or foam brush.
  4. Wait 24 hours between Tung Oil coats.
  5. Sand the first coat with ultra-fine sandpaper and remove dust.
  6. Apply the second coat and leave it to dry fully (cure).
  7. If needed, you can buff the finish using a polishing cloth.

While the Tung oil coating is drying, don’t expose it to high humidity or water as it can damage the finish. Tung oil takes around 3 days to dry fully (cure).

3. Use Polyurethane

Use Varnish (Polyurethane)

Polyurethane is a synthetic wood finish that creates a flexible moisture-resistant layer (barrier) over the bathroom wood and protects it from high moisture and water exposure.

Polyurethane is one of the strongest sealers you can use for interior and exterior surfaces as its flexible finish that withstand high water amounts and temperature changes.

Here’s how to use it:

  1. Prep the surface.
  2. Apply the first polyurethane coat with a paintbrush or spray gun. You can also purchase ready-to-spray polyurethane cans.
  3. Wait 6-8 hours between water-based polyurethane coats, and 24 hours between oil-based polyurethane coats.
  4. Apply up to three (3) polyurethane coats for proper durability.

How Long Does Waterproof Wood Last in Bathroom?

Waterproof wood lasts between 10-20 years in a bathroom. The exact time depends on the maintenance routine, wood quality, and sealer type.

For instance, bathroom wood sealed with polyurethane lasts longer than when sealed with Tung oil. Polyurethane creates a stronger and more durable finish than Tung oil.

Tony Adams

Tony Adams

Woodworker, Interior and Exterior Painter, Flooring Specialist

Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about.

Eral Kadrija

Eral Kadrija

Lead Editor, Home Renovator

Eral has a passion for home renovation and repair. Over the years, he has bought, renovated, and sold 7 old homes. Using his experience from different DIY projects he created DIY Geeks.

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