It looks great, but how does it get moved? It looks like it might attach to a car. I don't see any handles for pulling it or way to attach an animal to it. Interesting too they went for a tyreless wheel.
If you look at the front end (the non-door end) you can see one of the handles for moving it resting on the X-shaped piece of wood keeping it level. There would be a similar handle on the other side.
It would be moved by hand as it would only ever be moved short distances around the farmyard or a field.
At the most, the wheels might have had iron tyres shrunk on to them, but because the hen house is never moved far, wood rims are just as satfisfactory.