There is a variety of test methods used around the world, all of which are targeted at simulating the biodeterioration and exposure hazards encountered by outdoor deck structures in service. Most of these methods are essentially small decks, and are composed of deck boards fastened directly to treated wood joist members which hold the deck boards in place. Such methods serve as a test for wood preservatives that are intended for use in wood to be exposed to the weather out of contact with the ground without the additional protection of a surface coating (i.e. Use Category 3B). Because of their basic deck structure, most of these test methods provide little if any acceleration of decay beyond that encountered by decks in service, but rather provide a convenient method to compare a range of treatments or materials at a convenient location and using minimalized amounts of materials.
Accelerated exposures can be achieved by use of higher climate index test sites, while accelerated knowledge can be obtained through the use of quantitative measurements on sample parameters during the test exposure, for example by monitoring moisture content changes during exposure, or through periodic assessment of surface appearance properties such as checking.
More recently attempts have commenced to develop methods that are similar to the fixed decking protocols mentioned above, but which allow easier assessment of individual deck boards while still maintaining the fixed board characteristics achieved with the use of decks with applied fasteners to hold the boards in place.
Examples of standardized versions of this test method can be found in AWPA Standard E25 and AWPA Standard E28 (available from the AWPA).