Unprotected wood exposed to the elements is susceptible to deterioration and biological attack. The natural weathering process results in changes in appearance from the rich beauty of new wood to shades of gray and eventually to black. Left unprotected, new wood's durability, beauty and natural coloration suffers. The enemies of your exterior wood surfaces are:
Photo Degradation by Ultraviolet Light - Sunlight Solar radiation is the most damaging element in the outdoor environment, affecting every exposed surface. The first change you will notice is sun damage in the form of color change. Without intervention the rich woody golden brown color will turn to gray. Not just cosmetic, this color change is actually the decomposition of lignin (nature's glue binding wood cells together).
Leaching - Swelling/Shrinking due to Water Absorption Sun and rain cycles cause moisture fluctuations in the wood. The shrinking and swelling stresses the wood causing checks and splits to develop. Hydrolysis (as in acid rain attack) also contributes to degradation of wood.
Decay-Promoting Microorganisms - Fungi, Mold and Mildew Wood's natural protectants leach out in a relatively short time and allow colonization by wood-inhabiting fungi. Once established and aided by favorable climatic conditions, these microorganisms can have a rapidly devastating effect, causing wood to become soft, stringy, pitted, cracked or even to crumble.
Depletion of Old Growth Timber The majority of today's cedar and redwood lumber is being processed from younger, less decay-resistant trees. Young redwood and cedar lumber may need protection earlier than that of the mature trees that was once widely available. These factors, coupled with an increased awareness of the need to protect what remains of our old growth timber, are further reducing the supply of high quality wood.
Sunlight, water and fungi take their toll and you will soon notice unprotected wood becoming spongy, sidings beginning to curl, laminated siding, delaminating, deck boards and fences warping, spliting, and cracking. T111 siding is particularly suseptible because of its small surface cracks and splits.
WOOD WEATHERING IS DEPENDENT ON SEVERAL FACTORS
Slope - Wood's oriention to the elements dictates how quickly is weathers. Vertically and horizontally oriented wood differ in their photo degradation, leaching effects and vulnerability to fungi because they are exposed to different angles/levels of sunlight, moisture and dirt. The more horizontal wood is, the more likely it is to suffer decay from fungi.
Direction - South-facing wood suffers because it experiences the greatest swings in temperature and humidity, leading to more splits and other degradation.
Shading - Wood shaded by trees is more likely to develop mold, mildew, and decay than unshaded wood.
DON'T GIVE UP!
In spite of the exterior wood's relentless, natural enemies, not only can it be restored, in most cases, it can look like new. The transformation process involves repair, mold and mildew removal, wood surface preparation; and application of a protective coating.
Knowledgable, regular maintenance is key.
HOW TO PROTECT EXTERIOR WOOD
To keep your exterior wood looking like new, while avoiding the expense of replacing damaged wood, it is necessary to apply a water-resistant coating. This will protect your wood from its natural enemies: Sunlight, leaching and decay. Products which form a protective barrier on top of the wood may look good initially; but are of little value. They easily weather off, typically in less than a year. On wooden decks foot traffic quickly mars surface barrier products.
Penetrating products are far superior as they protect the wood by sinking into the wood fibers themselves. These are actually stains and they can last 2-3 times longer than surface film applications. The performance of exterior wood stains is a direct result of how much product is absorbed into the wood. For this reason it is best to allow wood fibers naturally age and open for six months to a year before applying the coating. The aging process can be accelerated by spraying the wood with a demilling glaze agent which opens up the wood fabric. Once this aging process is complete the wood must be cleaned and dried. For optimum results we perform the following steps: