I use 2x4 welded wire 14 gauge. Easily available at box stores like Lowe's for $37 for 4'x50' roll. That goes around perimeter then lengths of it are cut in half for 18-24 inch dig proof apron. That apron is laid on ground and staked in place or put just under the sod horizontally. From just under wall outward. Animals when digging will dig at fence line, hit wire and being 14 ga. can't chew through it so move to side and try again at the fence wall. They don't back up so 18 to 24 inches is wide enough to fool a large digging animal like dog or coyote.
2x4 inch squares wont stop weasels but then neither will 1" square. Lock the coop at night, every night and the birds are good. No other land predator can get in other than climbing.