A polyurethane roof coating provides a protective layer over plywood materials that helps to prevent moisture from damaging them. It is available in both oil-based and water-based variants and can be applied as a clear or pigmented finish. This type of protective coating is also a popular choice for use on exterior wood materials such as shutter louvers, deck boards and chair spindles.

Polyurethane finishes are renowned for their durability and create a hard, resilient surface that resists moisture, impact and abrasion. This makes PU ideal for high traffic areas and outdoor projects. When deciding whether to choose a water or oil-based polyurethane, consider the specific needs of your project. Water-based urethane typically dries clear but may yellow over time, whereas oil-based polyurethane is nonyellowing and retains its clarity.

Weatherproofing Your Plywood with Polyurethane: Tips and Techniques

When applying a coat of polyurethane, be sure to follow the manufacturer’s instructions and allow sufficient drying time between each application. It is also important to sand between coats for a smooth and consistent result.

The right sanding techniques will help to ensure that your finished coat of polyurethane is as smooth and blemish-free as possible. Be sure to use a good-quality natural-bristle brush and work in a well-ventilated area. If you are using oil-based polyurethane, expect to wait 48 hours before walking upon your finished floor and up to a month for the surface to cure properly. A bonding primer can make the sanding process easier and eliminate the need for hand sanding.