Plywood bows in the middle of a 12-foot sheet surprised me last Thursday

I stacked some 3/4 inch birch flat in the garage for 3 days before cutting cabinet doors, and the middle sheets had a 1/4 inch hump from just the weight of the pile. Has anyone else had their lumber supplier's storage cause weird warping right out of the stack?

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2 Comments

parkerk562mo ago

The 1/4 inch hump is probably from the veneer layers inside the sheet, not just the weight. Those inner plies can have uneven moisture content from the factory, and 3 days flat isn't nearly enough time for that to even out. Your supplier's storage might get the blame, but that birch could've been bowed before it ever hit their racks.

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matthewf402mo ago

You're surprised a 1/4 inch hump happened from stacking 3/4 inch plywood flat? That's pretty normal for birch, especially if it sat in the supplier's warehouse a while before you got it. Throw some weight on it and see if it flattens out before you worry too much.

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