how to apply polyurethane to wood floors

How to Apply Polyurethane to Wood Floors

So you’ve finished installing those hardwood floors, awesome job! But wait, you aren’t done – do you know how to apply a polyurethane finish?  You wouldn’t want all your hard work to go to waste. Would you?

Polyurethane acts as a shield for your wood floors. It protects the wood from the scratches and spills that come with everyday life. Urethane is available in two varieties and several sheen levels, ranging from glossy to matte.

The application process can be tricky, so you’ll need to brush up on your skills. Here’s what you should know before attempting a polyurethane finish.

Should You Use Water-based or Oil-based?

To start with, you must decide whether to use an oil-based or water-based product. Both will protect your floors, whether you have traditional or engineered hardwood – but there are notable differences.

Waterborne polyurethane goes on clear and will not alter the color of the wood. It’s thinner than other solutions and dries quickly. You can walk on your floors within 8-12 hours of application.

Water-based finishes are less flammable and don’t contain harmful VOC’s. They won’t emit strong odors or fumes. When it comes time to clean-up, all you’ll need is soap and water.

This type of polyurethane is the most expensive and least durable. Because these urethanes are comprised of fewer solids, you’ll need to apply several coats for maximum protection.

If you seal your wood with a water-based product, expect to repeat the process every 2 years.

Oil-based polyurethane enhances the coloring of the wood and gives it a soft glow. Due to their composition, oil-based products are thicker and take longer to dry. They do emit fumes, so prepare to don

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There is an upside to this type of urethane. Oil-based products fortify the wood with a solid layer of armor. They take fewer coats than water-based poly, and cost half the price.

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What Materials Do You Need?

It’s time to whip out your pen and paper (the list is longer than you’d think). But, don’t worry – most of the products are inexpensive and can be found locally.

Once you’ve decided on which polyurethane you’ll use, it’s time to research brands. It’s important to choose a brand that’s upfront about the chemicals and storage requirements. Look for a company that offers telephone support, in case you need advice.

Unless you have one on hand, you’ll need to rent an orbital sander from your local improvement store. Be sure to buy sandpaper in varying levels. The pros recommend you purchase 36, 60 and 120 grit to start.

Don’t forget to grab 220 grit sandpaper and a pole sander for between coats. If you don’t want to buy a pole sander, you can make one out of a broom handle and a sanding block.

You’ll also need urethane rated brushes and a lambswool or synthetic applicator. You can use a T-bar for getting into corners & doorjambs. T-bars work best with water-based formulas, so you may want to buy a roller instead.

This project requires a shop vac – borrow one if you need to (or check out our review of the 6 best Shop Vacs). Remember to pick up a respirator and some gloves. Masking tape and mineral spirits will come in handy during prep, make sure you buy them.

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Time to Prep

Now that you’ve got the shopping out of the way, it’s time to prepare your workspace. This is the most crucial and tedious part of the process.

Begin by vacuuming your hardwood floors and set yourself up to start with a clean surface. Dig into the corners and clear away any dust or cobwebs. Open some windows and let the room air out a bit.

After you’re done, it’s time to start sanding off the old finish. If you’re not sure how to operate the sander, queue up some online tutorials. Start with the roughest paper and work your way up.

Don’t sand in one area too long or you’ll risk scoring the wood. Check the surface one last time for splinters or dents.

When you’re done, vacuum away the dust and wipe the boards with a lint-free cloth and mineral spirits.

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The Application Process

Now, you’re ready for the main event. Start by stirring the polyurethane with a paint stick. Never shake a can of polyurethane, you’ll sabotage the finish with air bubbles.

Load your brush or applicator with poly and tap off any excess. Pick a corner and start working about a foot out, going in the direction of the grain. Use long overlapping strokes to ensure an even coat.

Look for signs of dripping and correct these spots before they dry. Wait a few minutes after the first coat, and check one more time for blemishes or places you may have missed. Apply the polyurethane to the corners and blend it into the boards.

Let the first coat dry completely before restarting the process. Be sure to read the manufacturer’s guidelines on drying times. Once the floor is dry, you can wet sand any drip marks or imperfections.

Repeat the application as needed, allowing the floors to dry between coats. Most wood floors require 2-3 coats, but it’s best to check with your flooring manufacturer before calling it quits.

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To Sum it up

Finishing your wood floors with polyurethane isn’t rocket science, but it IS hard work. Applying the product requires a combination of ability and knowledge.

As with any home improvement project, careful selection, and proper preparation will affect your results. Take the time to practice your technique on scrap wood. The most important thing to remember is to let your floors dry before sanding or walking on them.

While it may feel like a never-ending process, take heart in the fact that your wood floors are timeless. With regular maintenance, they’ll look beautiful for years to come.

Have you tackled a polyurethane application? Tell us about it in the comments below.

Jeanine Hintze

About Jeanine Hintze

Jeanine Hintze is a professional content writer, and home improvement enthusiast from Long Island.

6 thoughts on “How to Apply Polyurethane to Wood Floors”

  1. Avatar
    Tom Sandretzky

    Hi, I installed refinished oak flooring from LL. The sheen isn’t what I was hoping for so I would like to top coat it with satin polyurethane. The floors are distressed so sanding with a orbital sander isn’t a option. I would like to clean the floors well and simply apply the satin coat to the factory coat. What do you think? Hanks, Tom

  2. Avatar

    Hello, we have 100 year old pine floors with lots of character. We would like put a Clear Matte finish oil base poly on them. Is there a brand you would recommend? Also should we use Oil base conditioner before, If so wondering what brand for that too? Thanks

  3. Avatar

    we just had our new hardwood floors stained and sealed. The color is beautiful but the floors are streaked and you can see every time the lambswool applicator was lifted. The man that did them is a professional with a large business. Not sure what the problem is? It almost looks like when you mop a floor with dirty water and it leaves streaks on the floor. Did they not clean it well enough after sanding and before sealing? We now have 4 coats of poly on the floors and they still look terrible! We don’t know what to do, we are wanting to move in and you’re right the smell is horrible!

    1. Avatar

      Sand it all off and go back with oil base…….Much better choice, lasts longer, looks better, easier to put on, cheaper, easier to repair if scratched. Only down side is the fumes……only lasts a few days. I have done dozens of floors and the only one I regret is the ONE I did with water base.

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