Exterior Wood Restoration
By Tom Williams, Western Wood Protection
Too hot to touch in the summer. Saturated with water for several months while the snow melts. Bombarded by ultra-violet rays from the sun. A source of food for mildew, fungus and other parasites. These natural decomposition processes, while beneficial in forests to break down dead trees and renew plant life, also break down the structural integrity and beauty of your wood deck and other exterior surfaces of a log or wood sided home. Having invested hundreds of thousands of dollars on your home, you do not want nature to cause premature decay.
Choose a product that will protect your investment and enhance the look of your home or deck. To adequately protect wood, a product should contain protection from ultra-violet rays, water, splintering, and fungus.
Ultra Violet Rays – During sunlight hours, we are constantly bombarded by UV rays. This energy from the sun is good for plants, but deteriorates dead wood, turning it from multi-grained to a solid gray. Most exterior wood finishes have semi-opaque pigments to block UV rays, but may also obscure the beauty of wood. A transparent finish should have a maximum amount of transparent oxides, a UV stabilizer and a UV absorber to enhance the attractiveness of wood and reflect the sun's rays.
Splintering – The sun and rain age wood by breaking down the fibers on the surface. As the wood goes through wet and dry cycles, wood cells can no longer bond to one another, so they crack and splinter, allowing water to penetrate the surface. A good product will help bond the fibers together. Oils also keep the wood moist and prevent it from drying out.
Water – Wood is porous and absorbs water. It swells when wet and contracts when dry, a cycle that breaks down the structural integrity of the bond between cells and promotes cracking and splintering. Finishes that seal the surface from the outside may flake off or crack when moisture attempts to escape from the inside. A good finish will penetrate into the wood surface, providing protection from the inside out, allowing the wood to breathe without trapping moisture inside. Beware, too, of paraffin-based products that will seal wood, but melt in hot weather.
Fungus and Mildew – Although the arid climate of the West inhibits fungus and mildew growth, it can be prevalent on north or wet sides of buildings. Wood is a source of food for some forms of mildew, fungus, lichen or moss. If allowed to grow, these tiny plants will consume the wood, causing the structural integrity to diminish. This rotting is very serious and can cause great difficulty and cost in replacement of affected logs or decks. Any finish should have some form of mildecide to inhibit fungal growth.
How long will a finish last?
The quality of the product used, the application, and the orientation of the surface all affect durability. Cheaper products do not last as long as more expensive ones with higher quality ingredients. An application without any surface preparation will not look as good nor last as long as one with proper cleaning and removal of old material. Additionally, horizontal surfaces, such as decks, take more of a beating from weather than exterior walls sheltered by eaves. Decks may have to be recoated every twelve to sixteen months, whereas vertical surfaces may last five to eight years or more depending on the orientation.
Surface preparation
All surfaces, new or old, should be cleaned with a pressure washer, preferably with hot water. Certain detergents or stain removers may be applied to remove dirt and old stain. If the grain is raised from pressure washing, then the surface should be sanded to remove the standing wood fibers (felt) and rinsed again to wash the felt away. For difficult surface removal, a corn cob blaster will take off most stubborn finishes.
Application
All products can be applied by brush, roller or spray. A six-inch brush is a good applicator, but slower than spraying. If spraying, all surfaces not intended for application must be masked with tape and plastic sheeting. After spraying, the material should be worked into the wood with a wide brush (back brushing) to force the material deeper into the wood and even it out. For better protection, apply two coats.
Homeowner can do the work themselves. However, a professional has the tools most homeowners don't have and can eliminate errors due to lack of experience. Don't be afraid to ask questions about how the work is performed and what materials will be used. An informed homeowner is rarely ever surprised by something unexpected.
Any unprotected wood will deteriorate over time. Just for a test, try scratching your home's finish with your fingernail. If it comes off, you may need to refinish. When exterior wood is properly cleaned and a high quality product used, a deck, log or wood sided home will remain beautiful for years to come. Remember, the beauty of wood lies just below the surface. 
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