Question: What is the service life of APA Wood Structural Panels?

Answer: It is not possible to provide an exact estimate of the life expectancy of wood products; however, when installed and protected properly, plywood and OSB will last the lifetime of the structure.

APA Rated Sheathing Exposure 1, which includes most structural plywood and OSB, is intended for use in protected applications such as floor, roof and wall sheathing. APA Rated Sheathing panels are wood composite panels that include two components: wood veneer or furnish and synthetic (e.g., phenolic or isocyanate) adhesive. Exposure 1 panels are made with the same exterior adhesives used in Exterior panels, have a fully water resistive bond and a high degree of durability. It is well known that wood has a long service life when properly designed, installed and maintained. Therefore, if the bond of APA Rated Sheathing is maintained, its service life should be comparable to that of solid wood.

Plywood and OSB have a long history of successful service. Plywood has been in the market place for 100 years and has been widely used in residential and commercial structural applications since the 1930s. OSB has been in the marketplace for more than 25 years.

The major environmental factors affecting the service life of wood and wood-based composites are: 1) ultraviolet (UV) degradation, 2) temperature, 3) fungi attack, and 4) moisture. Outdoor exposure studies by APA and others have shown that if plywood and OSB are maintained and protected properly, there is no reason to expect significant strength loss after many years of service.

Good building design, proper architectural detailing, appropriate product selection, and proper installation and maintenance will help to extend APA Rated Sheathing service life.