build a pergola over an existing deck. included in the free pergola plan is building instructions, a list of materials and tools you'll need, photos, and even videos. more .
over a rounded sitting area on a deck. it is so gorgeous because it has built in benches that create a cozy seating area. the pergola then goes over the already gorgeous sitting space. not only is the space inviting but it should also be very comfortable thanks to the shade the pergola can offer. build this .
it's impossible to suggest a proper structure without much more detail about the existing deck structure. a solution is very likely . you are basically building a parachute. . if you're going to have 1" x 1" wood going on top, 1" apart, depending on where the sun rises, you can go above your eaves. mine are .
make sure your deck is large enough to hold the pergola, and that it's raised high enough from the ground so that you can get underneath it to fasten the upright beams to the deck's . make sure that the same amount extends over the crossbeams, then secure them to both crossbeams with wood screws.