Just got 6 silkies and we're gonna need something 7x4 at largest. Preferably raised for flood season, with good ventilation and airflow for humid 98°F summers.
You could frame it with lumber, make a roof and a floor, and use hardware cloth for all sides. That would provide great ventilation. If you get a stretch where cold wind or rain is blowing in, just put a tarp over one or two sides until that's over.
Of course, putting it in the shade is a greta idea too.
A friend of mine built this in Texas, years ago:
https://www.shedworking.co.uk/2007/10/poultrenon.html
I'm told it worked well for them, but I see that it's not at all suitable for flood conditions. (But it is very well ventilated!)
Maybe a tree house for the chickens?
Or some kind of legs?
Or a foundation of concrete blocks?
I don't have experience with floods, so I'm just guessing here.
Are there building codes you can look at for your area? They won't want human houses getting flooded or washing away, so you might be able to get ideas by looking at what they do.
