I'm totally blown away by your brooders! My Chicks are living in a 3' X 3' rabbit hutch with a slightly raised floor in my heated shed. They have a little cardboard house that I replace every few days and a broom stuck thru the slats on the side to roost.
they are big enough now to not have any cardboard. The ducks are in a similar smaller cage and the pullets are going outside this weekend because they are just too big!
Here is mine. One 1 window found in the trash 4 pieces of subfloor leftover from a job and a small scrap of linoleum flooring. The top lifts off of the floor so you can take it outside a hose it off. Very easy and free and you can see what they are doing which is cool i think.
Here's my brooder condo -- 3 story high rise! I built it from 1 sheet of half inch OSB - the boxes are 2 x 4 ft, 2 10" high, one 18" high. The legs are 60" 2x4's set on with lag screws. The bottoms are made of hardware cloth (1/2" screen) and I line them with cardboard, newsprint, then litter.
I acquired a rabbit hutch from a relative and first put my six peepers in a box inside the hutch with the lamp and food/water, and then had cut a doorway in the box so that in the warmth of the day they could come out but were still safely enclosed in the hutch, and then one weekend I was out of town and a friend was checking in on them for me, and he told me that he had come over and found that some had been able to get over the box top. So when I got home I took the box out and then took a 1X8 and cut three walls, since the back of the hutch was already a board wall, and then they still had some protection from the colder night air, but full run of the hutch. They seem to enjoy their home and I am planning to expand it as they get older.