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Community and Q&A

Am I OK to lay down my plywood subfloor at 19% moisture content?

GreyWolf92 | Posted in General Questions on


I tested all of my 4×8 cdx plywood in the middle of the 5 sheets, and 2 pieces are at 19% moisture content (the rest are between 10-17%).

Should I go buy 2 new pieces or am I too concerned over the moisture content? I was reading that anything near the 20% range is way too high for plywood.

I purchased these 3 weeks ago and have been stacked in my shed. I did not test when I first purchased but I certainly would assume that they would be dryer.

Also, please see the pictures below. Does this look like water damage or mold? These are the two pieces that measured higher.

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  1. GreyWolf92 | | #1

    Here are the photos

  2. GBA Editor
    Martin Holladay | | #2

    Go ahead and install your plywood. Subfloors get rained on all the time. On a construction site, it's not uncommon to see puddles.

    Once your house is dried in, you can start paying attention to the moisture content of the plywood. Don't install your finish flooring until the plywood has dried out.

    -- Martin Holladay

  3. GreyWolf92 | | #3

    Ok thanks for weighing in!

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