Screw this warped floorboard!

Hello!
Got a (water-induced) warped floorboard. The "bubble" is about 18" or less, and it lays down ok when you step on it. I tore up the carpet in that area (getting new carpet later this week), and I'm pretty sure that it's just the panel (OSB) that's warped, and that it hasn't separated 'leaves' or anything.
So, depending on who you ask, sticking a couple of screws through this panel into the floor joist will work temporarily or permanently. I'm not sure what the floor joist is- 2x4, 2x6, etc... i'll have to look at it. I'm guessing I'll want to put the screws in opposing angles- str8 up and down might cause the wood to pull up.
Putting washers on drywall screws is probably not recommended either?
Should i drill some narrow pilot holes? I'm afraid that if i stick a few drywall screws in the joist it might split or something.
TIA for any comments.
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Provided the floor joist isn't rotting out, screwing it down is the best thing to do. Since it straightens out when you step on it, screws won't have any trouble pulling it in and making the repair permanent - criss-cross isn't necessary. If it's possible for it to pull up, the screw is too small!
Do NOT use drywall screws. They're too short and too thin. Overall, the bite will suck ;-), and the floor board probably _will_ rise.
2 1/2" (or 3") #8 (or #10) decking screws are the best way to go, and drive 'em in straight. They're cheap. 3" #8s can pull warped 1 1/2" decking (ie: 2x6s) into line. Don't worry about that part.
It wouldn't hurt to predrill pilot holes - #8/#10 screws will not split joists if they're in good shape and you hit close to the center of the joist, but, predrilling pilots will make certain of it. It's more advisable with #10.
I use 2 1/2" #8s for plywood and 3/4" floor sheathing. I reserve the 3" screws for 2x lumber decking. #10 for extreme cases. #8 is by far the most commonly used size.
Washers not necessary. Just countersink the head slightly with the driver.
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phaeton wrote:

Drywall screws countersink themselves no pilot hole needed, and it's highly unlikely they will split any 2x anything. I would use at least 1 5/8" or more.
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"you can lead them to LINUX
but you can\'t make them THINK"
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