We have a blue 55 gallon barrels attached to our kennels and during the winter we took insulation and wrapped around each barrel. (We have two runs on our above ground kennels.) And then wrap that insulation around with tarp to keep dry with tin roofing covering it as well. and you put your hand in there to pet the dogs or add cedar chips and the temperature difference is unbelievable. Here in Kentucky it’s been in the 30s lately and the dogs drums are as warm as a heated dog house. And in the summer the barrels are very good and breathable.
Years ago, I used the (food grade) plastic barrels. On the upper end, I cut three sides of a 9 inch square, then used a torch to heat the fourth side until it would bend up to form an awning for the doorway. After it cooled, it would stay in place. Worked well, except the barrels were hard to clean out and I eventually stopped using them.
I use 30gal white plastic barrels for all my dog houses. I just cut a small round hole in one end for them to get in and out. Attach it to a couple 2x4s to keep it from rolling. Winter I fill with grass hay, summer I put nothing in it. Spring they get scrubbed out.
I use them put I cut a hole in the side so the dogs can have a place out of the wind if you cut out on the top or bottom the wind can and will blow straight in on them also use cedar chips for bedding in winter
A little different BUTT the same Idea--I use a Rubbermaid trash can and cut a entrance hole in the small (Bottom) and wrap the outside with insulation the lid is held on with bungee cords VERY easy to clean and ad bedding .
I have some that were given to me I love. It’s a 55 g barrel cut in half and slides over a cattle mineral bucket with an entrance hole. Barrel section lifts off to fill with cedar chips. I’ll get some pictures when I get back to the house