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Warranty of plywood core cabinet doors… what's the deal?

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AWMAC by Audra Denny
Audra Denny is Executive Director of the Architectural Woodwork Manufacturers Association of Canada.
audra.denny@ awmac.com
AWMAC is frequently asked the same question, “Will cabinet doors with a plywood core within my project be warrantied?” Let’s set the record straight. The simple answer is no, but lets delve into the reason why.
As you may know, plywood is created in layers of wood; wood is a natural material and is bound to expand and contract. What complicates the process more is that each wood layer expands and contracts at different rates. All these changes will cause internal tension within the layers of wood, which will naturally lead to warping over time, especially with a pocket-door system. Referencing the NAAWS Manual, 10.6.8.7.1 and 10.6.8.7.2, cabinet doors with a plywood core will not be warrantied, as it’s susceptible to “telegraphing, delamination and warping.”

According to AWMAC National Board Vice-President Mark Whitman, he’s used to fielding this question, “this is a common misconception and is brought up regularly at AWMAC Lunch and Learns across Canada.”
Plywood is manufactured from thin layers or plies of wood veneer that have been glued together. Did you know there’s usually an odd number of plies so that plywood sheets are balanced? This helps reduce warping but doesn’t negate the issue completely. The pioneering of plywood dates all the way back to 1797, when Samual Bentham applied for several patents, and referred to the concept of laminating several layers of veneer with glue to form a thicker piece, which is how we recognize plywood today. The plywood process was brought to North America in 1865, and it’s the same process used in shops now.
What about combination core plywood? Combination core plywood is typically a mix of veneer core layers with MDF or other composite layers. In theory, combination core plywood is more stable, but it may still have warping and twisting issues. We often hear about manufacturers talk about their cabinet-grade plywood, but the same issues may apply. A million-dollar idea for the woodworking industry would be for the invention of a true cabinet grade plywood, as it currently just doesn’t exist. The bottom line is, there are many types of plywood available, and some are more stable than others, but at the end of the day, plywood is all created in layers and will all have the same issues over time. They are guaranteed to fail at some point.

Can I still use plywood core doors in my projects?
Plywood core doors can be used for all casework products and cabinet doors; the manufacture, edging and construction techniques are all widely accepted within the industry. Simply put, it’s up to you. All millwork items will be warrantied with the exception of the cabinet doors containing plywood. With any project that requires a certified AWMAC Inspection, this would be noted as a non-warranty item in the shop drawing report, the mock-up report and the final report.
 Whitman’s recommendation is to reach out to your local AWMAC Chapter if you have any questions, as they have experts in place to guide you along. AWMAC offers free lunch and learns across Canada, to find your local Chapter, visit www.awmac.com. Additionally, if you’d like to become an expert on NAAWS and have a manual of your own, you can download it for free at www.naaws.com.

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