Can You Apply Roof Coating Over Plywood?

Yes, you can apply elastomeric roof coating over plywood—but with some important caveats. Elastomeric coatings are highly flexible, waterproof membranes that are typically used to protect and extend the life of roofing systems. While they are compatible with a variety of surfaces, including exterior-grade plywood, proper preparation is absolutely essential to ensure durability and performance.

Before applying the coating, the plywood must be clean, dry, and structurally sound. Any damaged or rotting sections should be replaced, and the surface should be free of dust, oils, and other contaminants. It's also recommended to use a primer designed for wood surfaces to improve adhesion and seal the porous nature of plywood. Without a primer, the coating may not bond properly, leading to peeling or water infiltration over time.

Additionally, elastomeric coatings are not a substitute for a full roofing system. If you're applying it directly to plywood without any other roofing layers (like underlayment or shingles), it should be part of a comprehensive waterproofing strategy, possibly including reinforcing fabric or mesh in seams and joints. This is especially important in areas prone to heavy rain or humidity, like Florida.

In summary, elastomeric roof coating can be applied over plywood, but only if the plywood is exterior-grade, properly prepped, and ideally primed. When done correctly, it can provide excellent waterproofing, UV protection, and extend the life of the roof surface.