How to Waterproof Wood for Bathroom Use

If you’re placing wood in a bathroom then it will 100% be exposed to water at some point, so it is important to waterproof it.

Here are 4 effective ways to ensure that wood in your bathroom will last for years to come:

1. Use Tung Oil

Tung oil is well known for its ability to waterproof wood effectively.

The oil, which is an extract made from tung tree seeds, has been used for centuries as a wood finishing product.

Its protective properties are what make it stand out from other oil finishes.

tung oil waterproof wood

In addition to being eco-friendly, it improves the water resistance of woodwork and protects it from environmental damage.

Tung oil is a drying oil; which means it doesn’t just form an outer protective layer on the wood, it also gets absorbed into the pores of the wood, providing more waterproofing and protection.

If you apply tung oil correctly your wood will be able to withstand bathroom moisture with no problem.

How to Apply Tung Oil to Wood?

The process is easy. Yet, it takes time. The following steps will guide you through it:

  1. Clean the wooden surface thoroughly and sand it until the surface is nice and smooth
  2. Clean any dust or debris with a wet piece of cloth
  3. Using a brush or lint-free cloth, apply the first layer of tung oil on your surface in the direction of the wood grain
  4. Let the layer of oil dry for at least 6 hours
  5. Once the first coat has completely dried, use sandpaper to smooth out the surface
  6. Apply another coat and leave it for another 6 hours to dry
  7. Repeat the process until you have a minimum of 5-6 coats of tung oil

The Benefits of Using Tung Oil

While being an aesthetically pleasing finish, it provides protection for the wood in addition to other pros including:

  • It’s non-toxic
  • Doesn’t rancid or become yellowish over time
  • Resistant to acids and alcohols
  • Can be applied by any beginner
  • Resists the mold

Uses of Tung Oil

Tung oil is perfect for both interior and exterior woodworks. It’s used as a finish for all types of wood, including:

  • Dining area and kitchen surface
  • Doors and windows
  • Hardwood floors
  • Kids’ furniture and toys as it’s non-toxic
  • Cutting boards
  • Countertops

2. Use a Wood Sealant

Sealants like Varnish, Lacquer, or Polyurethane are popular for their quick-drying and good-looking finish. They provide waterproofing for wood in your bathroom.

apply a wood sealant


Varnish has been a popular choice for years, to the point that people call wood finishes a ‘varnish’.

It provides a thick layer of protection that resists scratches and doesn’t rancid or become yellow over time.

It contains a combination of oils, resins, and solvents. 

varnish application

Varnish can be applied as a spray or with a normal brush.

Whichever method you choose, it will dry in noticeably less time than other methods.

Marine varnish has better waterproofing capabilities; in addition to protection from various chemicals and UV light. 


Polyurethane is a sealant that contains a mixture of acrylic, polyurethane, and various solvents.

It gives the wood a stunning glossy look.


When it’s dried, it becomes a hard, durable shell that protects the wood against scratches and makes it waterproof.

Yet, it’s mostly made of plastic, so that makes it susceptible to cracks and weak against heat.

Which Is Better: Varnish vs. Polyurethane

Polyurethane is more durable and dries faster than varnish.

However, it’s slightly more toxic and more expensive than varnish.

Marine varnish is the best choice for places exposed to excessive moisture, like your bathroom.

Yet, other options can work perfectly.

How to Apply Wood Sealant?

Before applying wood sealant, don’t shake or stir the package. It may form air bubbles that will decrease the efficiency of the sealant.

The following steps will guide you through applying wood sealant:

  1. Clean the wooden surface thoroughly and sand it
  2. Clean any dust or debris with a wet piece of cloth
  3. Apply the first coating of sealant by spraying it or using a brush
  4. Let it dry out completely
  5. Apply a second coat and let it dry
  6. Repeat the process for a third coat
  7. Let it cure for at least one day 

3. Use a Stain-Sealant Combo

Stain-sealants will not only waterproof the wood, but will also give it a colorful look. As some types of stain-sealants contain color pigments.

wood stain helps waterproof wood

The stain-sealants get absorbed into the wood and the excess amount evaporates, leaving a thin layer on the wood.

The application process is just the same as the previously mentioned processes:

  1. Clean the wooden surface thoroughly and sand it
  2. Clean any dust or debris with a wet piece of cloth
  3. Apply the first coating of stain-sealant
  4. Let it dry out completely
  5. Apply a second coat and let it dry
  6. Repeat the process for a third coat
  7. Let it cure for at least one day 

Advantages of Using a Stain-Sealant Combo

A stain-sealant combo has many advantages, including:

  • Availability of various colors
  • They create a thin layer. Yet, it’s efficiently protective
  • If you apply an extra amount, it’ll evaporate
  • It gives a smoother finish

4. Use Paint

Some paints like shellac can be used to waterproof wood in your bathroom.

paint for wood waterproofing

However when painting be aware that any missed spot not covered in paint (even the smallest spot) will leak moisture into the wood.

For the best results use shellac as a first coat on your wood, then apply any other type of clear oil, wood sealant, or stain sealant to ensure that it is completely sealed and waterproof.

How to Protect Bathroom Door From Water

While any of the previously mentioned will be fine, tung oil is the best option to protect your bathroom door from water.

It’ll also add a stunning look to your door.

Can You Waterproof Wood for Shower Use?

Yes, but it will require the right type of wood and a lot of waterproof sealant.

Teak wood is a great option; it was used to make Japanese wooden bathtubs and the decks of the old ships so it has high levels of water resistance.

With enough layers of a good sealant marine varnish or tung oil, voilà! You’ll be able to waterproof any wood in your shower!

a bathroom styled with lots of wood

Can You Put Wood Planks in a Bathroom?

Engineered hardwood is the safest option if you’re planning to have a wooden bathroom floor. Yet, it still isn’t a completely safe option.

It’s important to understand that this needs to be done by an expert. You don’t want to see mold eating out your bathroom floor!

Teak wood is a safe option. With a good sealant marine varnish or tung oil, your bathroom floor will be waterproof.

However, there’s a price to pay for the amazing look of a wooden floor. It won’t withstand a plumbing problem, and you’ll have to wipe it after every shower or water spillage.

Go Waterproof The Wood In Your Bathroom..

Adding wood to your bathroom will give it an extraordinary look.

Taking steps to keep your bathroom dry are the best way to protect your wood however if you want to use wood in your bathroom you should also use teak wood as this has high levels of water resistance, you should then seal it using a sealant for the best results.

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