Building pergola with two rows of 3 posts. I'd have 2x10 beams mounted on the posts supporting the 2x8 rafters, but I'm curious how far apart I can push my rows of beams. Ideally I would love to have them 13' apart with the rafters cantilevered 18" on either end but I'm worried I will have sag.
I should note that I am planning on having 2x2 slats on top of rafters spaced every 12". Also, will be using PT lumber. Thanks