How to Waterproof a Wood Floor

A water spill on wood flooring.
What You'll Need
Vacuum aspirator or other fume protection
Vacuum cleaner
Wool mop (or other natural thick material mop) or special applicator
Polyurethane sealer

There is nothing that makes your home look as neat and cozy as wood flooring. Today, wood is as popular as it used to be before the carpeting craze; its earthy color and warm look give a welcoming impression. However, taking care of the dust and damage is not enough to make a wood floor last. It needs proper maintenance and care, and waterproofing is an important part of the magic formula. Think about how many times you or your kids accidentally spill water or milk or track mud from outside. Without protection, wood will soak it in and, after some time, gain dark spots that damage its appeal. Once upon a time, people used different oils, oil-based products, and waxes to keep their wood floor in good shape, but now, there are more durable, stronger polyurethanes or resins that will make waterproofing that much easier with the right instructions.

Prepare and Purchase Sealer

Preparing the floor for waterproofing is a very important first step. Start by sweeping and vacuuming the surface to make sure it is free of all dust and debris. Then, check for any old stains and damaged spots, and remove or fix them. Don’t forget to move all pieces of furniture outside the room and secure proper ventilation as well.

Tip: When planning a wood floor waterproofing, make sure you choose a string of warm and dry days because rainy days and high humidity can make the coat drying much longer.

Based on the wood and its quality and age, choose the proper type of finishing material to use. Most commonly, people opt for urethane, with either an oil or water base. Also, make sure to check that your choice of sealer is a good, penetrating variety.


Start sanding the wood surface with medium-grit sandpaper, making sure to really spend some time on it. The more thorough you are, the better the final result will be. Afterward, clean and vacuum the floor surface one more time, and make sure to dust walls as well to get rid of lingering sawdust. Cleaning is the most time-consuming part of waterproofing.

Lay the First Coat

Add the first coat of sealer to your wood floor using an old-fashioned trick: spread the urethane with a wool mop or any mop made of thick natural material. You can also buy wool applicators. Using this material will ensure a smooth and even first coat, which is important for an equally even final result. When finished, air the room out and let the floor completely dry.

Add Subsequent Layers

Make sure that the first coat of sealer has dried for the appropriate amount of time as indicated on your product. This will prevent possible headaches by adding the next few layers. When it's finished, smooth out all bumps and wrinkles in the initial coat with sandpaper so they do not appear in the finished surface. Sweep and vacuum all dust again before you lay the next layer with your mop.

Some homeowners continue to add more sealer but this can be unnecessary if the wood is in good shape or if it's newer and the two previous coats were done well. Regardless, a third can give a better look and stronger waterproofing. If you choose to add it, simply follow the same procedure as before: let the urethane dry completely, smooth out imperfections, clean, and finally brush on the new layer.