I had it built after I bought the house. It was built by "Four Season Sunrooms". It's on an 18 X 20 foot concrete slab with ceramic tile over it and has a cathedral ceiling. It ate up my inheritance from my parents (and then
some) but it was a great investment. I really enjoy it and my plant / pet collection has grown to match it.
I do not have any building skills so would not attempt something like this myself !!!
This is what was attached to my house when I bought it:
So, I put up the sunroom on the same 18 X 20 "foot print":
And I have been filling it with plants ever since!