I am in the process of adapting a steel building into a new coop for my 7 girls. The entry to the coop is approximately 21" from the ground (12" from the floor of the coop (deep litter). I'm making a ramp for them to get up to the door that will be hinged to raise like a draw bridge to close up the pop-door. First question: how far apart should I put the cross pieces to make it easier for them to get up the ramp to the door? Second question: I'm using a 4'x1' piece of 1/2" inch exterior plywood with 1x1 reinforcement on the back to keep it fairly rigid. Is that long enough for the 21" drop. (I'm math challenged, and I can't find any guidelines anywhere. It doesn't seem steep to me, but I'm not a chicken.) third question: The girls are now in a ground level coop. No steps to get into the coop. they roost on roosting bars that are about 2' off the floor. Should I anticipate any problems getting them to use the ramp? They are very curious about the building and drove me nuts today when I was trying to paint inside. They were hopping up into the people door that is about 9" off the ground to get in with me and watch me paint. They will be moving from a 4x4 space to a 6x8 space, so I hope they will enjoy the room to stretch during bad weather. The race is to try to get the thing up and running (even without the run -- they free range in my yard 3-5 hours a day) before bad weather hits.