Base prep for concrete slab

[stealman]

I have prepared the base for below the concrete slab. The base is 3/4" crushed drain rock. It is flat within probably + or - 1/4". I am using 3" of ridged foam over the base. Because the base is not perfectly flat the insulation rocks on the high spots and sags a bit on the lows. Not a lot, but enough to wonder how this will affect the concrete strength? I am worried that I will have small hollow pockets below the insulation. The drain rock it next to impossible to get perfectly flat. I would like to get some feed back. Thanks

 

[astroracer]

4 or 6" pour? Either way, if all you are concerned with is 1/4", the weight of the concrete will "level out" the insulation... There will be no rocking once the pour is done...
Mark