[Hetmann]

We did this in our front yard a few years back. We had a large slab for a front patio that was over 50 years old and we poured a second one next to it. These were tied together with rebar. We covered both as well as a long sidewalk with red flagstone, approximate area about 1200 square feet or so. Pretty big patio.

We had a mason install the flagstone. I believe he just used portland cement as a bed carefully leveling each stone, I do not remember any thinset. He also grouted with portland cement. As I recall, he did not score my old slab and the new slab was not highly finished. The patio has been through several freeze thaw cycles and has developed some cracks. We have a crack or two through stones where the two slabs meet, however the majority of cracks have developed in the grout lines and folow the edge of one or more stones. On the whole it has held up very nicely. We have had a little spalling of some flagstones, but nothing major.