the decision of wire vs netting for the pen top is largely a matter of "How much do you worry about raccoons, foxes, etc climbing over the pen walls". If you will shut the chickens in a secure house in the evening and are willing to take your chances with the low, nonzero rate at which they hunt in the daylight hours, netting would be ok. However, wire (and not just chicken wire) gives a much better level of security.
Note that for honkin' big pens, like 20x20 or something like that, wire may be impractical anyhow.
Pat
Note that for honkin' big pens, like 20x20 or something like that, wire may be impractical anyhow.
Pat
