Today the grand children and I went to clean out the hen house. While the kids were working I took measurements, this is what I found. The coop is set on 8 foot stilts with two sides closed off, the other two sides have chicken wire and a trap covering them. The coop is 16' x 20' x7'. As it gets cooler they start filling in under the coop with all the plants from the garden, lawn clippings as well as the bedding from the horse stalls. By the time it is cold, it is pretty much full. Every week he turns as much as he can and adds some fresh material. The kids had the windows open while they worked up a sweat and the outside temp was about 45 degrees. I turned some of the material under the coop and it was down right hot. I can see how a fire might happen. Paul told me, his grand father used this to heat his house for the first few years here. He learned it in his home land. It works for him but I think my chickens will have to do with a 60 watt light bulb. It is way to much work for me.