The ladder type roost was very simple, just figure your angles out for top and bottom of the side boards than all I did was rip a board in half and used that as the stairs of the ladder, I think I made my stairs 18in apart. The materials was used treated 1x6 or 2x6 decking, just make sure your roosting post is higher than everything else including nesting boxes or they will try to roost on the boxes ext, most boxes have an angled top for that reason, only reason mine is flat because it's easier to build and I have the option for a 3rd tier of staggared boxes, I will prob buy a cheap tarp to nail up at an angle so they don't land on my boxes. Than again the materials used on my boxes were used sheets of 1/4 plywood, only thing I bough for those was the plastic bins which are awsome, clean out is a breeze. Only thing I will change is I'm gonna cage in under my roosting areas so they can't walk in the poo and track it around, unless you clean it out regularly, I'm gonna frame mine in and try sand under them. Also there not glorious flyers so they need room to land off the roosting posts, a ton of feeders and waterers to dodge can be tricky for them, try to keep those out of the way if there in the coop.
