Question
We have a cement/peagravel patio and would like to have a smooth stone, such as flagstone, put over it.  We would also like to extend it over an area that is currently grass.  Is is possible without having to jackhammer the existing patio?

Answer
Yes, but it is likely the "cold joint" between the new and old "sub-slab" will transfer through to the surface of the new stone, so I would put a joint in your stone there or run a saw across the new stone at the location of this "cold joint" cutting it 1/2" deep min.

All you need to do is clean or acid wash the old concrete so you get a good bond and then mortar the new stone to the surface and grout the joints.

Best of Luck
Sean J Murphy, LA,ISA, LEED AP
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