[Vipergrün]

Thanks for the replies! Good information and food for thought.

While the spans, for the most part, are not that long, I plan on using 6x6 posts, 2x12 ledger boards, with 4x12 and 2x8 making up the rest. One section will be a 12'x12' square and I hope to use 4 4x8 'beams' to create a 12/4 pitch roof, which I will cover with either Sunbrella canvas or perhaps tongue & groove wood.

At this point, I like the idea of just digging footings at the edge of the patio, rather than trying to cut the existing concrete.

I built a similar structure on a house 15 years ago and it's really holding up well. In that case I got to do the footings before the patio was poured...