The back brace pieces are 19"

First I primed all the pieces and then painted the first coat white. Laid them flat together, then Drew out the design. Using outdoor paint I painted each slat. Knowing that mine would only be seen from one side the backs are solid, but they could be painted to be seen from both sides.I assembled the pieces starting with the top slat flush with the top of the brace pieces. Using two long paint stir sticks together in-between the slats for spacing. I used galvanized screws to assemble. The bottom slat hangs slightly longer than the brace. When finished I went back and touched up where the the screws were inset.