Apron for predator control

[Jeffery Vance]

I am thinking about building some tractor pens 4x8 and 4x16.    Has anyone used a 2 foot apron around to keep predators out. Using 1/2in. By 1/2 inch wire.  If so would love to have all the feedback
That we can get.  My plan is to have pens that I can move around on the grass and dirt.  And then be able to fold the apron up for moving them around.
      Around the pens it will be a 2 foot piece of tin as well as using 1 inch wire on all the pens.

[John W Blehm]

When I had my chicken condos I thought about stapling 2 by 4 inch welded wire across the bottoms, but I never had a predator dig under them so I didn't get a round TUIT.  The chickens would still get at the grass inside the pens and walk on the wire.  They wouldn't be able to take sand baths, but you could put a pan of sand in the pens for that and by not allowing the birds to dig up the area it would allow the grass to regrow when you move the tractor pen.
The apron sticking out could cause a problem if you mow over top and the wire gets in the blades. 
I used to have solid wood and steel around the bottom 2' or so of my pens to keep predators from coming thru the wire, but it stifles the air flow so I went with the plastic lattice, with small openings, fastened to the wire.

[Dennis Heltzel]

Here is a writeup, with pics, of how I build tractors with aprons that are very movable. I have used these for years with great results.
http://www.backyardchickens.com/a/hoop-tractor