Loose plywood sheet nailed to concrete

Old 08-26-08, 07:54 PM
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Loose plywood sheet nailed to concrete


We are reflooring our family room, which has a concrete floor covered with 8'x4'x1/2" sheets of nailed-down plywood. There is a step down from the kitchen which lands on an area of the plywood that is not flush against the concrete beneath it. Stepping in this area causes the plywood to depress about 1/2 inch until it hits the concrete. We ultimately want to cover the floor with carpet, but we'd first like to repair the bouncy plywood problem prior to doing so. I've attached photos of the area that I'm writing about. We are reluctant to pull the 8'x4' plywood up because it seems there are more than 100 nails in it, attempting to hold it flush to the concrete. Another thought was to force-depress the problem area by driving an anchor through the plywood into the concrete. At this point, we're pretty unsure about what to do. We'd greatly appreciate any and all thoughts/ideas! TIA

not depressed:

Old 08-27-08, 04:59 AM
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I don't want to bust your bubble, but the plywood should be removed. Place a vapor barrier on the floor, build a "sleeper" floor with pressure treated 2x4's standing on edge, then 3/4" Advantech subflooring on top of that. With that, you will alleviate any moisture problem you have, get the height you need, and achieve a solid substrate for your final floor treatment. And those concrete nails are only 1" long (my guess) and should pull up without alot of effort.

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