4 Simple Steps to Waterproof Wood For Your Bathroom

You’ve decided on wood for your bathroom.

The Zen like feeling of natural wood tones will calm you every time you enter. The thought of water stains on your beautiful wooden furniture does not. So how do you make sure your wood and water don’t mix?

With this article, we’ll give you all you need to know to waterproof your bathroom wood for years to come. We’ll discuss the various methods available and the pros and cons of each, and we’ll guide you through the simple steps needed to get a perfect result every time.

With our four easy steps:

  1. Choosing your waterproofing
  2. Preparation
  3. First coat
  4. Further coats

We’ll show you how to keep your bathroom wood looking beautiful year after year. Ready to learn how to waterproof wood for a bathroom in 4 easy steps? Then let’s get going!

What you’ll need

  • Safety gear (Some wood sealants can be toxic. Avoid getting them on your skin/in your eyes. And always follow the instructions on the container.)
    • Safety glasses
    • Safety gloves
    • Long sleeves/pants
  • Sandpaper (3 different grits, typically 80, 150, 400)
  • Cleaning brush/broom
  • Lint-free cloths
  • Paintbrushes
  • Waterproofing agents (See step 1 for help with deciding which agent is right for you.)

Step 1: Choosing Your Waterproofing

There are three primary methods to waterproofing wood for a bathroom. And the choice of the right method for you depends on several factors. Price, type-of-finish, and durability all play a role in deciding. So, let’s look at the methods and discuss the pros and cons of each.

Wood Sealants

The first method is by using a wood sealant. Wood sealants are popular because they have quick drying times and are reasonably priced. There are three main types of sealant:

  • Varnish
  • Polyurethane
  • Lacquer
male applying varnish on wood
Varnish gives protection and waterproofing for your wood.

Woodworkers have used various forms of varnish for hundreds of years as a means of protection and waterproofing. A varnish provides a thick protective coat that also helps the wood shine. For a bathroom, the best choice is to use a marine varnish that is specifically designed for waterproofing. They can be applied with a brush or a spray and dry within 24hours (usually a lot less). You can also pair a varnish with various wood stains if you’re looking for a particular color or finish.

Polyurethane sealant is usually a mix of resins and solvents. They can give wood different finishes depending on the product, including satin, matte, semi-gloss, and high-gloss sheens. You can also use an oil-based version for better durability, but most painters use the latex version. Oil-based poly takes forever to dry, which also increases the risk of a mess if there’s pets or kids around!

Lacquer is highly flexible and comes in several finishes. It provides an excellent protective coat and is probably the most durable of the three forms of sealant. But it will yellow over time, so it is best used on dark woods. Lacquer can be quite toxic, so keep this in mind when working with it and make sure you have excellent ventilation and wear a ventilator.

Resin and Acetone

The second method is to use a polyester resin and acetone. This can give an extremely durable finish. Which is an excellent choice for hard wearing furniture and floors. To do the job properly, you will need both a laminating resin and a finishing one. But if you only want to use one, we recommend a finishing resin because this will harden more.

The acetone is applied to the resin to make it thinner and easier to work with. Only apply as much as you need to get a mixture that is a bit thicker than water.


Just like the sealants, oils come in several options. The most common oils are tung, teak, linseed and walnut. It might be best to avoid walnut oil in a bathroom, as it can cause an allergic reaction in some people.

Male applying oil to waterproof wood
Oil has several options as well, which includes Tung, Linseed and Teak Oil.

Tung oil provides an excellent barrier and can be used on any type of wood. But it has a long curing time of 7-days or more. And it will require several coats to be fully effective. The major drawback to tung oil is its price, and it is easily the most expensive of the oils.

Linseed oil is cheaper than tung oil and comes in different colors and finishes. But it has an even longer curing time than tung oil, so you must wait awhile before your wood can come into contact with water.

Teak oil gives one of the best finishes and can look amazing in a bathroom.

If you use an oil, it can be a good idea to mix it into a more durable and stronger sealant by using turpentine and apple cider vinegar. 2 parts oil to 1 part turpentine and 1 part cider vinegar.

Step 2: Preparation

No matter the choice of method you decide, the way to ensure the best looking and longest lasting result is by excellent preparation.

First, remove any previous finishes and painting. Sand down the entire surface of the wood you will treat. Depending on the roughness of the wood use 150-250 grit sandpaper and make sure you get all the little nooks and awkward places.

Second, clean everything thoroughly using a general cleaner, and allow it to dry. The waterproof seal depends on an entirely clean, oil-free, dry surface.

If you are unsure of how your chosen method will look, we recommend testing a small area first. Choose somewhere out of sight and apply a small amount of your agent. Make sure you let the agent cure fully before deciding, because the look will change as it dries.

Some agents can give off toxic fumes while curing and can be harmful to the skin. Make sure you are working in a well-ventilated area and if you are working on movable furniture, consider taking it outside.

Step 3: First Coat

Once your surface is completely clean and dry, you’re ready to go.

Apply oil with a cloth. If you pour the oil directly onto the wood, it’s harder to get an even surface. Wipe the cloth across the wood, ensuring a smooth, even layer. Too much and it will puddle, too little and it will not form a barrier. Leave the oil for around 30 minutes and then wipe off the excess with another clean cloth. Leave the first coat to cure for 24 hours.

For a sealer you can use a brush or a roller. Be careful when mixing the sealer as you don’t want to leave air bubbles as these may stay as the sealant dries. Again, try to get a nice even coat and apply in the direction of the wood grain if you can. Remember, the fumes from the sealants can be dangerous, so use a respirator and make sure the windows are open.

If you’ve chosen resin, avoid getting it on your skin. Once your resin and acetone mixture is ready, you can apply it with a brush or a roller. Follow the instructions on the container, but we recommend letting the first layer dry for an hour. This way you’re less likely to damage the first layer when applying the next.

 Step 4: Further Coats

No matter your sealing agent, they will all require several coats. The number depends on the type of finish, the durability you require and obviously, the type of sealant.

For best results with oil, we recommend at least three coats. Let the first coat cure for 24 hours before applying the second. And make sure the second is dry before applying the third (around six hours). For best results, make sure the surface is clean before applying each layer. It can also be a good idea to give each layer a gentle sanding. Once you’ve finished, make sure you let the surface cure for at least 24 hours before you use it.

Sealants dry quickly, meaning you can usually apply multiple coats in a day. Some varnishes can dry in as little as 15-30 minutes. But others require up to 24 hours, so always check the label. If you don’t let them dry between coats, you’re waterproofing will not be as durable. It may be necessary to sand each layer so again, check the instructions. Most sealants will require two to three coats, but there are some that only require one. We recommend a curing time of 24 hours when you’re finished, just to ensure everything dry.

With resin, it is best to apply multiple coats and for the best finish and longest lasting result we recommend five. But with resin, you only need to let each coat dry for between 30 minutes to an hour. So, it is still possible to finish in a day or two. Each layer will need to be mixed separately so keep this in mind and only mix just enough, so you don’t run out for the later layers. Once finished let the whole thing cure for 12 hours.


There you have it. The 4 steps for waterproofing wood for a bathroom. Whichever method you choose, follow these steps and you will have waterproofed wood that will look amazing. Just remember to repeat the process regularly to keep your bathroom looking perfect for years to come.

Now it’s time to make your decision, head down to the local hardware store and buy your supplies. Good luck on your waterproofing project!

Hi there! I’m Craig, and I’m the founder of Appliance Analysts. When it comes to appliances and anything electrical, I’ve always loved opening things up, figuring out how they work, and fixing them. This website is where I share free advice from myself and our experts to help our readers solve their appliance/HVAC problems and save money. Read more