[TrickyDick]

We are doing a bluestone patio off the back of a house and it's kind of a wierd situation. There was an existing concrete pad about half the size of the patio with a footing under the outside of it (a frost wall?). We had to cut the concrete around a couple a sets of wooden stairs and pillars so we could dry lay the blustone while leaving the concrete that all ths stairs and stuff are sitting on intact. Finally got the pad out and found that underneath is where all the concrete slops were dumped from the footing so there is an uneven concrete surface that varies from 4-8 inches below finish grade. Can we lay our base on top of this? My concern is that the uneven surface may cause some uneven settling of the base. The job has not started well and I don't want to have to add on removal of this whole thing if I don't have to.

[TrickyDick]

Anyone?

[joshuatree]

if installed correctly your base should not settle that much. If those concrete slops have been there under the slab for a while I dont think they are going to settle anymore. I might tamp the earth then put a fabric down to further ensure minimal settlement.