So some snow load w/ possibility of needing/ wanting to stay in coop during winter storms.
I'll preface w/ I'm not a builder w/ wood. I like re-cycling, up- cycling & easy. I live in the south now & LOVE my open air hoop coops.
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BUT I've lived in the west & distinctly remember 2 blizzards that I'm really glad I didn't have birds in... 1982? thanksgiving or Christmas ? crippled CO. It wasn't far from house to barn w/ 4 stalls (but more than 4 horses, I think) - but we lost the shoveling battle & by time snow stopped we were tunneling under roof top high drifts to bucket water to the horses from the house. The "frost free" hydrant in the barn froze... Neighbors had to have feed, hay & some groceries airdropped in. Then in 1997, as moving from MT back to NC, a whopper slammed down out of Canada (IN April!!). We spent 5 days in a hotel... very little outside contact w/ family (they said OK, before power lost), friends or employers (no cell phones or google yet - we had CB radios in both vehicles). On the road again & as going south passed southern power trucks headed north to re-establish 100s of miles of power lines through at least 4 states......
There were storms in between, in various states & overseas, but those 2 .... are "imprinted"...
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Can you remove either the front, one end or the back of your coop to make it large enough to accommodate the number of birds you have w/ a little extra space? If so, then you can add in the ventilation that you need. When you build in the extended portion of the roof, you can extend it, so that the open ventilation is protected from the weather.
Unfortunately, since I'm not a builder, I have no other info as to best way to do that. Hoping others might chime in. There are a lot of designers & builders on BYC.
Edited to add - Alaskan has a great article on winterizing/building coops in cold/snow covered climates. Covers - ventilation, insulation, space, heat, water & outdoor runs here on BYC.
