Pressure treated plywood on concrete basement floor

Hey guys, I'm looking for some advice on a tough basement question.
Here's the background: Our house was built in 1928 and believe it or not, the concrete floor is in great shape. There are no cracks whatsoever, and it is 99.9% of the time dry. The basement is split in half, one half is the workroom and the other half is a finished part that used to have wall to wall carpet with an underpad.
Well, living in NH, we experienced a couple week's worth of constant rain in May that caused a ton of flooding statewide in parts of the state that are not prone to flooding. In our case, I'm sure the problem was that the water table rose too quickly and submerged the basement. The water seemed to seep up from the floor, not come in through walls or anything. It only ever accumulated to about 1/4" though, nothing too crazy.
Anyway, our carpet was ruined and now we need to figure out how we want to resurface the finished part of the basement. The trouble with the concrete is that it is painted in spots and very very rough (although no cracks). Also, it has a few (very few) spots that bulge upwards (less than 1/2" though).
We've decided that we want to lay FLOR carpet tiles (http://www.interfaceflor.com ) in the basement. They can be laid on wood, sealed concrete, tiles, etc.... Now the concrete itself is too rough to accept these tiles so we're going to need something put on top of the concrete.
I was first thinking of laying Ditra down using thinset, but now I'm shying away from the idea... .first, it is a horribly tedious job trying to clean up the paint which I'm assuming needs to be removed for the thinset to adhere properly. Also, I'm not sure if you'd be able to "feel" the Ditra underneath the carpet tiles since Ditra has those square "bubbles"...
Our latest eureka idea was to just lay down pressure treated plywood directly to the concrete and attach the carpet tile to the plywood. I know it would be better to have 2x4 spacers fastened to the concrete and the plywood attached to the spacers, but this is not an option as our current headspace is hovering around 6.25'.
Do you guys think it would be ok just laying down the plywood directly to the concrete, shimming where necessary? Or should I use 1x3 furring strips instead of the 2x4s just so I have SOMETHING (I have a feeling they won't be solid enough, though), or should I definitely go with the Ditra and not worry about the thinset on painted concrete since the paint is old and doesn't seem to be sealing anything anyway?
I assume the plywood would have to be fastened using a powder gun, right?
And finally what about this crazy idea.... just spread out some sort of skim coat of cement to even out the concrete, seal it and apply the carpet pads directly?
Again, this basement seems to only get water in record rainfall incidents, and even then less than 1/2" of water... would it be ok for the plywood to just sop that up since it's pressure treated, and we can temporarily remove the carpet tile in the affected area to let the plywood dry out.
Any advice is welcome,.. .thanks guys.
G
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Wow I was tiard just reading this post......Forget about the wood on the floor you have the clearnce issue and I just dont think it is necessary for you, nor a good idea given your possiable water problem. If the floor is painted "in places" try to remove as much of this as you can then acid wash the entire floor with a muratic acid solution (wear a respirator and open the doors and use a fan) after cleaning the floor (moping with a vinegar and water solution) several times you are now ready to apply your top coat of cement product. There are several products for the available at most home stores..to insure as best bond as possiable paint the floor with a concrete bonding agent ( 1 gallon containers looks like elmers glue in the area with masonry products) before you place the material. This process will cost you avout 1/10 of your other method and be a much more stable floor. With the wood you have alkinds of high andlow spot issues you would never get it right..nobody could i dont think unless you use fir strips, shims ......just to much work Why not resurface the concrete and stain it? Have you seen the price for the carpet tiles wholey &*^% that money could go into some pretty nece area rugs and your pocket....just a thought
Gino F. wrote:

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FIRST FIX THE WATER PROBLEM IT WILL CERTINALLY REOCCUR!:(
Inside french drain with sump pump.......
doing ANYTHING to pretty up a area thats had water infiltration is a terrible idea.
the next flood might be worse.
FIX THE WATER!
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I agree - get the water problem fixed or you will be replacing again. Check out whoever you use in your area, even check the company with the BBB. We had several contractors quote us, some appeared to be real dirtbags when you checked them out. One was even recommended by a neighbor. Well this past spring the neighbor had a flood in the basement with their contractor, ours was still dry using a well known 'franchised' contractor.
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No offence, but the above is the only potentially viable approach I find in your query.
And that -only- after installing at minimum a sump system (pit, pump, etc).
I, also, have had to discard a basement rug or 2 ...
Cheers, Puddin'
On Sun, 20 Aug 2006 13:39:30 -0400, "Gino F."

Pease pudding hot, Pease pudding cold, Pease pudding in the pot Nine days old.
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Gino F. wrote:

Exactly the same trouble encountered here. I recommend to use what is locally sold as FL flooring. 4 feet wide and up to 300 ft long sheets. Its a bubbled plastic and works well under 3/8 plywood subfloor, then top with whatever.
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Gino F. wrote:

goal to have a completely flat floor? is it just a good looking carpeted area?
If it were me I would just go ahead and put in new carpet and pad. There are pads that will not absorb water so if you have issues again you can maybe just replace the carpet. Your headroom is so low you do not want to do anything to impact that. Just use a relatively inexpensive carpet and be done with it.
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