Each pen has it's own chicken access door that is on a pulley. They are weighed down so when they are closed no animal would be able to lift them. The two smaller pens are 6 1/2 feet wide by 10 feet long. I have only 6 to 7 chickens in these. The larger back pen is 7 feet by16 feet. I currently have only 9 chickens in there, but will be adding more when my chicks in the basement grow up. When you first walk in I have a nice area for storing feed, bedding, and equipment. Then the hall that goes in between is 3 feet wide which makes it easy for cleaning. Total it is 16 feet x 20 feet. As for the cost..... Around $3500.00, but remember we did all of this ourselves and w/ friends (an electrician and construction supervisor) The concrete floor my in-law did for me for only $300.00 (cost of the concrete trucked in by a friend) - I knew I'd be glad my sister married him! I was just really lucky having friends that I have and a willing DH to do most of the work.