It seems there's a consensus here that 2x2's are a waste of time and insufficiently strong for a chicken coop.
I have to say this kind of surprises me. I'm thinking about building a bike shed (so maybe I'm slightly off topic since this is a checken coop discussion), and considering the last one that I tore down was made from light flimsy aluminum with barely any structure (a prefabricated metal shed) and it lasted 15 years through all kinds of rain, wind, snow and abuse, it seems like making a structure out of 2x2's would be a huge step up in strength from that.
There are also these kits which they sell -- brackets for making easy-to-construct sheds out of 2x2's (
https://www.ezframestructures.com/) that are up to 10ft by 16ft. And even though they are spaced about 2ft apart, they claim the structures are good for snow and wind and perfectly strong. Are those guys crazy?
It seems to me that if you build your roof out of 2x4's, it's going to be so heavy that you will need 2x4's to support it, and if you build your roof out of 2x2's it's going to be light enough that 2x2's can support it. Likewise, flimsy aluminum will support flimsy aluminum. If I pick up a 2x2 and try to flex it, there's some give but it is certainly a lot more rigid than my aluminum shed.
I'm not really clear what it is about chicken coops where everyone feels they need such a heavyweight solution. But there does seem to be something in the air where everyone has convinced everyone that 2x4's are the only material to build with. Can anyone explain this a bit more?