How to Apply Polyurethane for Floors

Your beautiful solid hardwood or engineered wood floor deserves the best possible finish. Polyurethane floor finishes are easy to apply, and they cure rapidly. They offer rock-hard, waterproof, long-lasting protection for flooring, plus they let the beauty of the natural wood show through.

What Polyurethane Finish Is

Polyurethane finish is a liquid resin used to coat wood flooring and other wood surfaces, such as cabinets and furniture. As a synthetic floor finish, polyurethane is made from raw materials that are derived from crude oil. 

Polyurethane floor finish comes in either water-based or oil-based versions. Water-based polyurethane is easier to work with and quicker to dry but wears down faster than the oil-based finish. Oil-based polyurethane finish, while hard and durable, is noxious when applied and takes at least twice as long to dry.


Oil-based polyurethane finish is more work during and directly after application, but this is balanced by the need for fewer reapplications and less maintenance. Meanwhile, water-based polyurethane is less work at the beginning, but it does require frequent touchups and reapplication about every two years. The frequency of reapplication depends on the amount of traffic on the floor, along with any potential damage from pets and UV rays.

Polyurethane finish is transparent. It comes in a range of sheens, from flat to glossy. It resists fungus, mold, and mildew well. One feature that makes it particularly good for flooring is that it is waterproof. Because polyurethane dries to a hard finish, it’s especially good at resisting scratches and scuffs.

Basics of Polyurethane Floor Finishes

Oil-Based vs. Water-Based Finishes


  • Slow drying time

  • Cleans with mineral spirits or paint thinner

  • Extremely hard surface

  • Pungent odor

  • 500-600 square feet per gallon

  • Best for all areas, including high-impact areas

  • Transparent, but with a slight amber tint


  • Fast drying time

  • Cleans with water

  • Hard surface, but not as hard as with oil-based finishes

  • Low odor

  • 260-320 square feet coverage per gallon

  • Best for moderate or light-use areas

  • Completely transparent

Number of Coats

Most manufacturers of polyurethane finishes recommend a minimum of two coats to achieve the desired level of durability and sheen.

Drying Times

Water-based polyurethane floor finishes generally dry to the touch in about two hours and can be recoated in about four hours. For oil-based finishes, double the drying time. For either finish, the floor should be safe to walk on after about 48 hours (but refer to the manufacturer’s instructions to be sure). Allow one week for the surface to fully cure.

Temperature, humidity, and ventilation affect drying times. Keep the room between 55 and 90 degrees Fahrenheit and maintain a relative humidity of around 50 percent. If necessary, increase humidity with a humidifier or decrease it with a dehumidifier. Ventilating the room with a fan on a low setting will expedite drying.

Alternatives to Polyurethane

Though polyurethane is the most popular type of on-site floor finish, some alternatives offer other advantages and disadvantages:

  • Penetrating Oil: Penetrating oil soaks into the wood and requires several coats. It sheds water but isn’t good at resisting scratches.
  • Varnish: Made from wood sap and alcohol, varnish predates polyurethane as a floor finish. Varnish has more solids than polyurethane, producing a thicker coating.
  • Wax: Wax is spread in multiple thin coats after the stains have been applied. Then, it is buffed to the desired level of gloss. Though wax is inexpensive, it does require frequent reapplication.
  • Aluminum Oxide (Pre-Finish): Aluminum oxide is an extremely hard finish that rivals even oil-based polyurethane’s durability. The downside is that it cannot be reapplied on-site; it can only be applied in the factory when the floor is being manufactured.

Safety Considerations

Sanding, scraping, or removing old paint on floors can be hazardous if that paint contains lead. Lead is toxic and can cause illness and even brain damage in children. Always wear a NIOSH-approved respirator. Clean up with a HEPA vacuum and a damp mop. Adhesives may contain asbestos. If you believe that the surface may contain asbestos, have it tested before sanding it.

Disclaimer: Curated and re-published here. We do not claim anything as we translated and re-published using google translator. All images and Tattoo Design ideas shared only for information purpose.

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