Subfloor problem

Our house, built in 1999, has a first floor laundry room that has a squeaky floor. You can feel the tile (vinyl floor in there) give a little bit when you walk on a certain spot.
When doing some work in the basement, I decided to dig into the issue finally. The washroom is over the crawlspace - about 4 feet of room there to work in, so I have options.
What I found as the problem is that the subfloor (looks like 1/4 or 1/2" plywood sheets) was damaged before installation. There are spots on the plywood sheet where it looks as if a pieces of the plywood were gouged out or just chipped out. So in these "weak" areas, there is no consistent support from the joists under the floor. So while the floor is fine on each side of these spots, on those spots there's like a 1/4" space, hence the "give" when walking up there.
I tried shims, but they just don't seem to be working very well.
I had considered simply taking a 2x4, wedging it vertically as a support between the subfloor and the concrete slab of the crawlspace.
But considering the crawlspace has some room for me to work in, and I am starting to use it to store things, I was wondering if there's some other option that will not leave me with a post coming down to the floor.
Thanks for any ideas.
john
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I recently repaired my subfloor, but am otherwise a beginner, so you should take what I say with a grain of salt. Here's what I would do, as suggested to me by this newsgroup. I'm assuming that the damage is all in one joist bay that is readily accessible. Also, this will take care of the damaged subfloor, which may or may not fix the floor problem you are observing above.
Fill the obvious voids with Bondo, so that the undersurface is fairly smooth. Cut a piece of 1/2" plywood to a width to just fit between the joists, and long enough to cover all the damaged area plus a few inches at each end. Install the plywood to the underside of the damaged subfloor with subfloor construction adhesive and a few nails to hold it in place while the adhesive cures.
Be sure the nails are short enough so that they do not penetrate all the way through the existing subfloor. The existing subfloor is likely at least 3/4", so a 1" nail would be fine, but if it really is 1/2", use a shorter nail. Alternatively, you could hold it up with some temporary bracing to the slab floor below.
Hope this helps.
Cheers, Wayne
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On Mon, 23 Feb 2004 16:07:52 GMT, Wayne Whitney

one of the things I had thought about doing was a 2x4 running between the top of the joists there, so I'd have more support also in the area between those joists - which I will still do, but bondo or some other "filler" had never crossed my mind - even though hearing it, it sounds like an *obvious* solution. :D
As they say about the forests and the trees...
"Damn forest!!! Can't see the trees!!!!!"
thanks!
John
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