Help Desk Question: Marine-grade plywood as exterior siding

Posted At : January 12, 2010 9:13 AM | Posted By : Help Desk
Related Categories: Plywood,Residential,Siding,Help Desk

APA Help DeskQuestion: Is it appropriate to use Marine-grade plywood as an exterior siding product?

Answer: At first glance, Marine-grade plywood would seem to be an excellent panel for siding applications. After all, it is intended for boat building; so one would think it must be decay resistant, have a superior glue bond, and perhaps hold up to weathering better than other plywood panel products. Unfortunately this is a common misconception.

  1. Although Marine-grade plywood is uniquely suited for boat building, it is not preservative treated to enhance its decay resistance.
     
  2. The adhesive used to bond Marine-grade plywood is not unique. Marine-grade plywood is bonded with the same type of adhesive as other Exterior panels including APA Rated Siding panels. All Exterior panels have a fully waterproof bond and the glue bond is intended for applications subject to long-term exposure to the weather or moisture.
     
  3. Sanded face Marine-grade plywood may also not the best choice from a visual standpoint. Face checking, due to weathering, is much more noticeable in a sanded veneer panel. A check is a naturally occurring lengthwise separation between wood fibers parallel to the grain of the veneer in a plywood panel. It occurs normally in solid or laminated wood products exposed to weather and can be expected on non-overlaid veneered panels, even when the panels are finished with paint or stain. APA Rated Siding panels have a textured face veneer and the checks tend to blend with the textured veneer resulting in a more visually appealing surface.
     
  4. Marine-grade plywood is also considerably more expensive than APA Rated Siding products.

APA Rated Siding is available in a broad range of appearance face grades, and in several surface pattern and texture combinations. If a designer wants plywood siding with a smooth finished surface they should consider specifying MDO. With such a variety, architects can specify a siding product that expresses their design intent.

For more information, refer to the following publications available from the APA Publications Library:

Note: This entry was originally posted by the APA Help Desk on April 24, 2006. It was updated on January 12, 2010.

 

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