bob haller wrote:

-snip-

patio under a large tree?

your probably better off with a paving stone patio, and just level
ground and accept pavers may need re leveled in future.

proper site prep digging down for gravel base etc, then ground stone.

doing that around a mature tree may prove to be difficult to
impossible, large roots and possibly harming tree

It depends a lot on the tree. My paver patio starts about 6'-8' from
the base of a 200 yr old Swamp Maple. These trees have a lot of
surface roots-- and some of them go 50-60 feet from the base of the
tree. When installing the patio I chopped off roots as big as 4"
in diameter, to a depth of almost 3 feet.

The most severe trimming of the roots was in a semi-circle that was
about 25% of the tree's circumference. Similar trimming had been
done a couple years earlier - 15-20 feet from the tree, in an adjacent
20% or so.

The tree never noticed.

Might be better off to dedicate some chairs for that area and
attaching pads to chair bottom so it cant sink in!

mature trees are a asset to be protected

I'm with you here-- This huge old maple is really too close to the
house, but it gives lots of shade, syrup when the spirit moves me, and
a bunch of character to the dooryard.

Jim