How Do I Make My Hardwood Floors Water Resistant?

Hardwood floors are luxurious and highly durable, but exposure to water will result in damage. This article shows you how to make your hardwood floors water-resistant. 

To waterproof hardwood floors, you should use an oil or water-based polyurethane waterproofing sealer to preserve the wood. Apply the polyurethane waterproofing sealer with a wool roller to create a smooth finish. Install an underlay and vapor barrier to prevent moisture from rising from underneath.

Let’s find out how to waterproof hardwood floors so that they stay protected for years. We explain all aspects of waterproofing hardwood floors here to make it easy.

Should Hardwood Floors Be Waterproofed?

Hardwood floors are subject to water damage. To keep them in good condition and protect them from damage, hardwood floors must be waterproofed. To correctly waterproof hardwood floors, you need to apply a high-quality polyurethane sealer. An oil-based polyurethane sealer is known to be highly durable and requires less maintenance.

Polyurethane sealers are a synthetic liquid resin used to seal wood flooring made from raw materials obtained from crude oil.

Polyurethane wood sealers are the best choice for waterproofing hardwood floors. However, to ensure thorough water resistance, you need to install an underlay and vapor barrier underneath the flooring to stop moisture from rising. Waterproofing underneath the hardwood floor with a membrane protects the floor and your home against water damage.

When making your hardwood floors water-resistant, you protect your floors against permanent stains and water-related damages for years.

Waterproofing also protects the hardwood floors from contracting or expanding, which causes cracking and warping through the years.

How to Make Your Hardwood Floors Water Resistant

To waterproof your hardwood floors, there are two options of polyurethane sealers available to use. You could choose an oil-based polyurethane sealer or a water-based polyurethane sealer. Whichever one you select, both offer good results.

The Best Option – Oil-Based Polyurethane Sealer

Oil-based polyurethane sealers create a hard protective coat and use fewer coats than water-based polyurethane sealers.

An oil-based polyurethane sealer is the most durable option; however, it has a sharp odor. The room will have to be ventilated for a few days while it dries. Unfortunately, the smell can last for weeks. You should use a respirator when applying an oil-based polyurethane sealer. Oil-based polyurethane sealers will turn the floors darker over time.

An oil-based polyurethane sealer will take longer to dry than a water-based sealer. Oil-based polyurethane sealers typically result in a darker rich, golden color when they mature. So, keep this in mind when you decide to use an oil-based sealer on your hardwood floors. Oil-based polyurethane spills can be cleaned up with mineral spirits or paint thinner.

This polyurethane sealer is self-leveling, meaning it will become smooth when applied. Allow an oil-based sealant to dry for 24 hours.

Oil-Based Polyurethane Pros and Cons


  • It offers a hard-shell coating.
  • It provides a high surface cover.
  • It requires fewer coats.
  • It matures into a rich golden amber color.
  • It is self-leveling, leaving a smooth finish.
  • It covers 500-600 square feet per gallon.
  • It is perfect for all areas and high traffic floors.


  • It requires a substantial drying time.
  • It has a sharp lingering odor while drying.
  • It is difficult to clean up and requires mineral spirits or paint thinner.
  • It remains sticky until completely dry.

Water-Based Polyurethane Sealer

The more straightforward option is water-based polyurethane sealants, which are easier to apply and maintain. They also don’t have any accompanying smells and dry a lot faster. Like an oil-based polyurethane sealer, a water-based polyurethane will form a hard protective coat, but more require a few applications.

However, water-based polyurethane sealers take longer to apply because the floor needs multiple coats to achieve the best result. Water-based polyurethane sealers are less durable, particularly in rooms with high traffic, fluctuating temperatures, and direct sunlight. Water-based polyurethane looks milky-white in the can but when it dries becomes completely clear.  Water-based polyurethane sealers are quick and easy to apply. Clean up afterward takes no effort with a water-based product. Allow a water-based sealant to dry for 4 to 6 hours.

Water-Based Polyurethane Sealer Pros and Cons


  • It is completely clear.
  • It is odorless.
  • As a water-based product, it is easy to clean up.
  • Fewer coats provide a flexible finish.
  • It is ideal for light-traffic floors.
  • It covers 250-300 square feet per gallon


  • Several coats are needed to provide good cover.
  • It is less durable against scratches and scuffs.
  • It is difficult to determine where the sealant has been applied previously.

Oil-based polyurethane sealers require more work during the application but require less maintenance and reapplications. While water-based polyurethane sealers require less work at the start but need more reapplications and touchups every few years.

Materials and Tools Needed to Start

To start, gather all the items you need to do the job. Tools required are a waterproof membrane for under the floor, an epoxy primer, silicone, polyurethane sealant, a paintbrush or wool roller, a paint roller tray, a knife, painter’s tape, a caulking gun, a mop, or vacuum. Make sure you wear protective clothing and safety glasses to protect your eyes while working.

Install a Moisture Barrier

You should install a moisture barrier underneath the floors to protect the hardwood floors from moisture that can rise from below. These waterproof barriers are usually manufactured from plastic.

Remove the flooring and clean the subfloor, which is usually concrete or plywood. Unroll the waterproof barrier sheet on the floor.

Moisture barriers come ready with built-in adhesive edges. When placing the moisture barrier in place, overlap the sheets by six inches to ensure a strong seal. Reinstall the hardwood floors.

Sand and Clean the Floors

Polyurethane sealer will show surface inconsistencies, so before applying the sealer, make sure you adequately sanded and cleaned the floors.

It is essential to clean the hardwood floors thoroughly before applying a primer or sealant.  Grime and dirt will leave unsightly marks when trapped in the sealant. All sealers need smooth, level surfaces to ensure a long-lasting seal. Use a commercial wood cleaner to clean the floors thoroughly.

Vacuuming or dry mop to remove dirt and grime from the floor. The floors need to be sanded to remove the existing finish. Sanding improves adhesion. Use a power floor sander or sand the floor down by hand using medium-grit sandpaper. Keep going until the floor is even while removing any chips that might stand out. 

Now it is time to vacuum the floors again to remove the dust that accumulated after the sanding. A shop vacuum is a good option for this job because it is made for heavy construction work. Ventilate the room well to get rid of the dust.

Try to work on a warm, dry day because high humidity levels will cause the primer and sealant to dry slowly. Good ventilation is key to a successful application.

Apply a Prime 

Before applying the polyurethane sealant, you need to use a primer on the hardwood floors. Epoxy and water-based primers are perfect for the job. Follow the manufacturer’s instructions to ensure the primer is mixed and applied appropriately. 

Pour the epoxy primer into the paint roller tray and apply the primer to the floor in smooth strokes with a wool paint roller or paintbrush.

Start in the back corner of the room, work around the walls and keep applying the primer to the floor, working in small areas. Let the primer dry for four or five hours to ensure it is properly dry.

Fill Gaps and Cracks with Silicone

When the primer has completely dried, start filling in any gaps and cracks in the floor with silicone. This allows gaps between the wall and the floor to be sealed. Use a caulking gun to apply the silicone for a smooth application.

Use a paint scraper to remove the excess silicone. Let it dry for 24 hours to ensure the silicone are completely dry. 

If the floor has any gaps and cracks, moisture will breach and damage the floor. Sealing the gaps with silicone is vital to ensure a proper water-resistant hardwood floor.

Apply the Polyurethane Sealer

Precision is essential when applying a polyurethane sealer to your floors. Don’t cut corners. Before you start, stir, but don’t shake, the can of polyurethane because shaking creates air bubbles, which will leave air bumps on the surface. If the sealant is too thick, you can add some mineral spirits to thin it out to a thinner consistency that is easier to apply.

Pour the sealant into a painter’s tray and apply the sealant to the floor with a wool paint roller or sponge mop to create a smooth, even application.

Use the same technique as the primer when applying the sealant start from the back corner working outwards, so you don’t paint yourself into a corner use broad strokes that overlap each other. Let the first coat dry for 24 hours before the second coat can be applied.

Apply the Second Coat of Sealant

Once the first coat has dried, you should apply a second coat of polyurethane sealant to the floor. Follow the same technique as with the first application.

Let the second coat dry for 24 hours while ventilating the room well by opening windows and doors. You could also use a fan to speed up the drying process.

When the second coat has dried, thoroughly inspect it for any imperfections. If need be, apply to any spots that might have been missed. If it looks like a third coat of sealer might be needed, simply follow the process again.

However, most oil-based polyurethane sealers require only two coats. Wait a few days for the sealant to properly dry, then finish the hardwood floors by polishing them with a polishing product. 

You should never apply more than three coats of oil-based polyurethane to any surface. Water-based polyurethane sealants often require up to twelve coats. Luckily, water-based sealants dry within 4 to 6 hours. 

Drying Tips 

Humidity, temperature, and ventilation all affect the drying time of polyurethane sealers. Ensure the room where you are applying the sealer is between 55 to 90 degrees Fahrenheit with 50% relative humidity. You might want to use a humidifier to increase humidity or a dehumidifier to decrease it to 50%. Using a fan on a slow setting to ventilate the room will facilitate quick drying.

When Should I Re-coat My Hardwood Floors?

Most experts agree that hardwood floors need to be re-sealed every three to five years only. This is an estimate only if your floors are subject to high traffic re-coating could take place sooner. 

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How To Check If Your Hardwood Floor Is Water Resistant

The easiest way to check if your hardwood floors are water-resistant is to simply drop some water on the sealed hardwood floor and wait to see if it will soak into the wood. If the drop of water remains, your application is successful.


Hardwood floors are a sizeable investment, and keeping them in good condition is worthwhile. Your beautiful hardwood floors deserve to be protected from water damage and scratches.

Polyurethane sealants are easy to apply, offering water-resistant, strong, long-lasting protection for hardwood floors while allowing the natural beauty of the wood to shine through.

The best way to keep your hardwood floors in top condition is to make sure they are water-resistant. Moisture and water can damage hardwood floors, causing warping and cracking. If hardwood floors are left unprotected, the damage will be costly to repair.

To make your hardwood floors water-resistant, seal them with an oil-based polyurethane waterproof sealer or a water-based sealer to protect them. Applying a polyurethane sealer requires a bit of work, but it is worthwhile in the end because your floors will be water-resistant for years to come.

Now that we have shown you how to make your hardwood floors water-resistant, you can confidently apply the sealant to protect your floors from water damage.