I like the looks of the rough cut siding. Are you planning to cut some holes in it for some ventilation/airflow? You say you are going to put 50 birds in there? 8X16' going to be a little tight for 50. I have a 8X16' coop and with 22 birds it looked kinda full. I'm not trying to P on the parade but, just something to think about.
Jack
Jack