In our first article, we discussed the ambiguity that exists in the lumber industry when it comes to deciding whether or not plywood should be designated as “marine grade.” We discussed the APA – The Engineered Wood Association’s credentials as a nonprofit engineered wood product trade association as well as their specific standards for what makes plywood “marine grade” quality.
In this article, we’ll explore even more characteristics you can look for when it comes to making this determination. Then we’ll mention a couple of British Standards that may be helpful to explore in making your determination as well. In our final article, we’ll seek to compare and contrast specific applications for which this quality level of plywood may be desirable.
As we mentioned in the first article in this series, not every manufacturer or lumber dealer uses the APA – ETWA’s exact standards for determining if plywood is marine grade. Here are some things you can look for and ask questions about when seeking to make that determination for yourself before purchasing a product for your next exterior application.
Basic Marine Grade Plywood Characteristics
If you’re seeking marine grade plywood, make sure it is completely void of core voids. This is because any voids present within the core of the plywood will tend to allow water to seep into the ply. Water will then become trapped, and the plywood will be susceptible to rot from within. This grade of plywood should have required virtually zero core ply repairs. Too many repairs would also cast doubt on the product’s overall quality and durability.
Beyond the aforementioned waterproof adhesive required by the APA-ETWA, it should actually be made with Weather and Boil Proof (WBP) glue that has been boiled in water for over an hour without allowing plies to delaminate.
For even higher standards, check out BS1099 and BS 6566. These are voluntary British Standards for marine grade quality plywood. The BS1099 is a current standard while the BS 6566 was a previously recognized standard that has since been retired but is still recognized in the boat building industry. Serious boat builders or those seeking plywood of that caliber may find it helpful to familiarize themselves with these standards.
The general factors to consider in determining the quality of marine grade plywood you want for your project would be core construction, adhesive, species of veneer core, species of veneer face, and overall appearance. Last but not least, you’ll want to be sure to ask questions about how the plywood will be expected to perform when faced with different weather and climatic conditions over time.
Hopefully, at this point in our discussion, you’re getting a clearer picture of the different standards that are used throughout the industry to determine whether or not plywood can rightfully be described as “marine grade quality.”
In our final article in this series, we’ll take a practical look at how different standards of “marine grade plywood” actually perform in both boat building and other exterior applications. The standard you choose to follow when purchasing plywood for your next project should largely be determined by what type of application you have in mind.