Education Facility Managers

Polyurethane or Varnish: Which Should You Use on Your Hardwoods?

by Jason Brubaker

For many DIYers, applying a finish to your hardwood floor is one of the most important projects for home improvement. The two most popular options, polyurethane and varnish, offer different levels of durability and appeal despite being grouped together.

Both options have advantages and disadvantages, so your choice will ultimately depend on what floor you have as well as variables like desired look and where the floors are that you’re finishing.

Things to Consider

Before you start evaluating your options, you need to know a few things about your project to get the best finish:

  • Durability: How long do you want your flooring to last before you need to apply another coat? When assessing your options, keep in mind what your flooring will be primarily used for. If it will be subject to heavy traffic and wear, oil-based polyurethane is recommended. If it’s for a guest bedroom you rarely use, a water-based polyurethane will work well.
  • Toxicity: Remember that some finishes are flammable and contain more chemicals than others. This is especially important to consider if you have children or are finishing a floor in a poorly ventilated area, in which case you should go with a water-based polyurethane.
  • Color: Do you like the exact color of your flooring as is, or would you mind a slightly different tint or more glow? Some of your options will not affect your floor’s color, while others may.
  • Application: If you’re a beginner, you’ll probably want to use a water-based polyurethane, since it is easier to use than varnish or an oil-based poly. If you’ve been doing home improvement for a while and want to try a more bold product, varnish could be the right option.
  • Drying: Do you need to use your surface within the next 48 hours, or is there no rush? Some water-based polys take less than one day to properly apply, while varnish can take up to seven days.
  • Cost: This is probably the most obvious factor. Before you choose a finish, ask yourself if you’re willing to spend a little extra money for a higher-quality product. Oil-based polyurethane is the cheapest option, followed by water-based polyurethane, followed by varnish.
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Polyurethane is recommended over varnish for hardwood floors. When it comes to polyurethane, you have two choices. If you want a rich color without having to reapply coats, an oil-based poly is your best bet. If you’re looking for a more natural appearance with a low odor, going with a water-based poly is the right decision.

Despite its odor and higher toxicity, oil-based polys are slightly more durable and offer much better protection against heat. Water-based polys are more expensive, but dry quickly and do not affect the wood’s color.

If you want a finish for an area that will get a lot of traffic, oil-based poly is usually preferred due to its heat and moisture resistance. If you’re looking for a fast-drying surface that can be recoated without compromising the floor’s natural color, water-based polys are recommended.


Unlike polyurethane, varnish is designed for outdoor projects and is not typically used for indoor surfaces such as a hardwood floor. While polyurethane is water- or oil-based plastic resin, varnish is older and made from resins, oils, and solvents. Because of the higher ratio of solids, varnish is less susceptible to ultraviolet light damage. This protection makes varnish an excellent choice for projects such as outside decks and exterior furniture.

This finish gives a more tinted color when applied and requires more coats than polyurethane. Although it has better UV protection and is less toxic than polyurethane, the application process for varnish can be tricky as it’s prone to cracking, peeling, and bubbling which further exposes the wood to water damage.

Avoid damage to your finished product by properly applying the finish; this will prevent damages to your flooring. Use the correct solvents for thinning and allow enough drying team in between coats to prevent the varnish from becoming brittle. Thoroughly mix the coating ingredients to ensure the finish maintains its strength against elements (heat, moisture, etc.).

The Verdict

Overall, polyurethane is generally used for indoor household projects like bookshelves and desks, while varnish is popular for outdoor surfaces such as a deck. Both offer durability, varied color options, and protection against elements. However, when applying a finish to your interior hardwood floor, polyurethane is the better option.

While varnish provides value in its protection against ultraviolet light and natural durability, it is specifically designed for outdoor surfaces. Polyurethane on the other hand, offers durability and flexibility for interior projects.

When choosing a polyurethane for your hardwood floor, consider the surface’s purpose and look. If your floor will be subject to heavy traffic, an oil-based poly is the more durable choice. If you want to keep the wood’s natural look and are willing to go with the less durable option, a water-based poly is what you’re looking for.