Protecting your finish from outdoor elements Washington DC

Q: Our company builds and finishes exterior wooden doors out of either oak or mahogany. We have tried several different finishing materials on our exterior doors. When the doors are exposed to extreme weather elements without overhead or side protection, the finish on the doors will fail within a matter of months. The finish will peel on the joints, the wood color will fade, or in extreme cases, the glue joints start to come apart where moisture has penetrated the wood. What can we use to provide a more durable finish on our exterior products?

A: Where extreme climatic conditions exist, there are very few coatings that will protect the wood from any fading or other damage to the finish over time. The most bulletproof finishing system for exterior wood products is the acrylic urethane coatings formulated for exterior use. These two-part urethane systems are expensive but are worth the price. Normally, one to two coats of acrylic urethane sealer are recommended with up to two coats of two-part acrylic urethane over the sealer. Just be sure to carefully follow the manufacturers' recommendations for applying the finishing system. Many of these urethane finishes will have an anti-mildew additive added to the material from the factory to eliminate damage from a variety of fungi. I have seen these finishes resist the elements for over 15 years without having to recoat.

Ed. note: Phil Stevenson is the founder of the American Wood Finishing Institute (AWFI) in Vineland, N.J.