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The subfloor dips about an inch on one axis across the middle of the room. Structurally, I think this is due to old and rectified foundation issues. Since the dip is just 1-dimensional, can I install the flooring so the T&G bend with it? Or should I pull the entire subfloor up and level it at the joists?

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Can you? Well, assuming the room is of a reasonable size, the bamboo will probably conform well enough to the curve, especially if it's in shorter pieces so the end-to-end joints can take up some of the needed flex. Should you? I'm less sure about that, but I think I'd go for it. Basic principle of old houses is that NOTHING is actually square or level, and it doesn't usually matter much. – keshlam Jun 1 '14 at 15:37
Is it a floating floor? If so, go ahead and install it and see if it works. If not, dismantle and redo. My guess is that it will be just fine. – DA01 Jan 28 '15 at 17:33

I certainly would not lay the flooring down over an unprepared floor. I have done this and the flooring ended up splitting, cracking and making noise. I would reinforce the flooring and make it level with floor filler prior to laying the new flooring.

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Read the manufacturers installation instructions, which should specify the maximum subfloor variance.

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It's way outside the manufacturer's specification. But, I thought since my dip is largely 1-dimensional, I might be able to work around it. – Nate Wagar Jun 2 '14 at 14:13
So you have a 1" valley running across the floor. How wide is the valley? If it's 1" from joist to joist, you'll probably have issues if any joints fall along (or near) this valley. If it's 1" over a few joists, then maybe it's not so bad. You've got to remember, wood wants to be the way it wants to be. If you're pulling the wood out of shape, you're putting extra stress on whatever is holding the wood out of shape (nails, glue, etc.). Over time whatever is holding the wood could loosen, leading to squeaks, creaks, and outright failure. – Tester101 Jun 2 '14 at 16:06
It essentially spans the entire 12' width of the room. I'm sure some areas slope quicker than others, though. Since I haven't actually gotten the floor yet, I thought there might be enough play in the joints to allow it. – Nate Wagar Jun 3 '14 at 20:41
"play in joints" == "squeeking floor" – keshlam Aug 1 '14 at 16:04

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