Finished wood used outdoors can become unserviceable within a few years if not effectively protected against ultra-violet (UV) light and moisture deterioration. For exposed outdoor wood the finish is especially important, as it is the main defence against weathering. At the same time, extended service life, low-cost maintenance and, where possible, preserving the natural appearance of wood is increasingly demanded by customers.
When properly finished, exterior wood can last a long time. For example, latex paints have performed well for 10 years or longer. By comparison, improperly finished wood can fail due to flaking, cracking, erosion and discolouration after only one year of exposure. Finish lifespan depends on several principal factors including service conditions, wood substrate properties and finish type. Understanding these factors and how they link together is needed to maximize the performance of any finished wood product for exterior applications.