We are planning out our run and anticipating problems with digging post holes because of tree roots. We're thinking of having a free floating run with landscaping timbers or 4x4's for posts. 2x4's along the top and bottom for stability and to hold the hardware cloth firm, as well as hardware cloth for the skirting. Our main concern is the frost and upheaval issues come spring thaw. If we did dig post holes we'd be needing to go down about 4 ft. to get beneath the frost line. Does anyone have a free-floating run (in an area with significant ground frost)? Did the thaw cause damage to the run? What would you change if you could go back and do it again? We want to do it 'right' so we don't have to rebuild it again next year, but a free floating run sounds a lot easier. Thanks!