Pullum Sanctum Solarium/Chicken Sunroom?

[Jerhanner]

Has anyone ever built a little greenhouse for their girls to use in the winter? I was gonna use an old door, some chicken wire, and some plastic sheeting to make one. That way, when it snows I can drag it to the garage, but on nice sunny winter days, the ladies can retire to their sunroom without getting their feet cold. I can't come up with any reason for this to be a bad idea, but as a newbie I thought I had best ask just in case.
The one I'm making wouldn't be that tall, and would have a wooden floor:

 

[aart]

Not a bad idea...dragging it back out thru the snow might be a PITA.
Do you have a covered run for them....might be easier in the long run(haha!).