prepping for floating floor

I have read a number of posts regarding self-levelling a floating floor. In my case, I am working in a slightly below ground apartment suite that has a concrete floor. The room I am working in dips 3 inches over about 12 feet. I am trying to put in a floating floor since the old carpet was hideous, but do not want to create a mammoth job for myself as it is only a single bedroom and does not justify an extensive amount of work or money.

My initial hope was to simply ignore the slope. Although it would be nice to have it level too, I was more concerned with dips and valleys. If I am willing to put up with a slightly uneven floor, I assume that the primary drawback is &#39;bounce&#39; in the areas of the floor over a valley. I have also seen quite a variance in &#39;allowable&#39; flatness variations. I recognize that a &#39;proper&#39; floor should be something like < 1/8" over 8 feet, but have also seen posts that pragmatically indicate that even dips of 1/8" over a couple of feet may be acceptable, particularly if one can secure down the middle of these sections to make them less mobile. Also, I was wondering if realistically one can get away with less evenness in the direction perpindicular to the direction that you are laying the floor. I realize that this is all a little hacked, and not officially recommended, but would appreciate any feedback on these ideas - including future problems that any of these &#39;hack solutions&#39; may cause. (I don&#39;t mind losing out on the aesthetics of a perfect floor, but want to clearly understand any &#39;flaws&#39; that I may decide to live with).

By the sounds of it, one option is to fill the room with a layer of sand screed until it is close to level, and then (optionally ?) use a self-leveller to make it even truer. (this would bring the concrete slab above the low end of the drywall - I assume that I would leave a

I was wondering, however, if it would be a little easier (or advisable) to simply toss down some plywood and shim it where necessary to achieve a fairly even surface. This would also allow me to secure down any sections that may still &#39;bounce&#39; a little if the end job is not perfect.

The dip also rises again as the floor goes into the bathroom (where I was hoping to lay tile). This may also affect the decision above...(?)

Thanks very much,

- RG

I have a similar mess and am anxoous to see replies. There&#39;s a couple other avenues you can try:

2) Topping with high density high-tech concrete. May be marketed as Acousticrete. They prime your floor, mix up the stuff, and pump it in. Drawbacks - expensive; weight may further depress slab.