The problem with using oil based paint on wooden decks

A common problem is the use of the oil based paint on wooden floor surfaces and outdoor decks and patios. Unfortunately many paint stores and builders warehouses continue to sell oil based floor enamel for exterior wood surfaces. This type of product is extremely hard, and will never withstand the expansion and contraction of exterior wood flooring. The extreme changes in moisture content and temperature of the wood cause coatings to be sheared from the surface as the wood expands, and the coating doesn’t expand with it causing paint to crack and peel. New lumber is extremely high in moisture content and primers (especially oil-based) are unable penetrate the surface of the wood so they lie on top with little adhesion. This contributes to premature paint failure.

Another common problem that can cause exterior wood surfaces to crack and peel is moisture entrapment. The non-breathable nature of oil based paints causes moisture to be trapped just beneath the coating and fosters the growth of wood-decaying organisms. It also freezes in the winter months. The decay of the wood fiber leads to the release (peeling) of the paint film. Hairline cracks in the paint film, resulting from expansion and contraction of wood, allow further moisture intrusion, causing greater expansion of the wood, causing more cracks, allowing in more moisture, and on, and on, and on.

What to do when Your deck or patio paint begins to crack and peel?

Sometimes we see only spot failure. Unfortunately, oil based paint never stops hardening. Much of the paint that is currently intact, will eventually release. We really can’t predict how soon. When we encounter a situation like this, we generally scrape off as much failed paint as possible, then use a belt sander, or palm sander using 60 or 80 grit abrasive to remove the remaining coating. A final sand with 80 grit to leave a good profile for the coating.

Chemical strippers are an option, but we usually discourage the use of hazardous stripping products by homeowners. There are several biodegradable strippers available. We also sand the entire floor to remove any wood fiber damaged by trapped moisture. There are very few good-performing floor paints for exterior wood. If you absolutely want a solid painted finish, you could consider a premium Acrylic Floor paint, or a solvent-based product like Sikkens Rubbol DEK, which is the only flexible, breathable oil based wood floor coating (not a paint) that we are aware of. It looks like paint, but performs like a stain–no film to peel.

Each of your coatinss options has distinct advantages and disadvantages depending on your specific requirements and whether you are re-coating bare wood, or remaining paint. If you choose not to strip the entire surface, You will need to sand the remaining coating so the new coating will adhere to it. Sikkens Rubbol Stain is for uncoated wood only, so unless you get to completely bare wood, you should consider the acrylic floor paint, priming bare wood and existing paint with 2 different specialized primers we can discuss.