First of all the basement is dry, I have had a 4x4 piece of 6 mill tapped down there for 2 weeks and it is bone dry. Now, the slab is unflat as well as unlevel. Its highest spot is in the middle then it slopes about 3/4" over 10 ft left and right. It also has some valleys and ridges. What i was planning on doing, is laying down 3/4" rigid foam, taping seams, and then laying some 3/4 ply, and tapcon it all down. I have read of people using this method to level the floor. My question is do you think it would take enough of the unflatness out to lay laminate? I really wanted to avoid doing the self leveling underlayment. It will double my cost.
I understand it wouldnt correct any leveling issues, but the flatness? There are small ridges and valleys in the slab. I figured laying the foam and 3/4 ply would take most of that out. If not, I will just go ahead with the self leveling underlayment.