The last owners of our house had a porch added. We dug up the tarmac drive in April and found concrete underneath so we carried on. Now the drive has not been finished but the porch is pulling away from the house. I think the porch was just built on top on the concrete drive and as we have taken most of it away the porch now doesn't have any support. Can anyone suggest what we can do to make the porch more stable until we can rebuild it. How can we tell how much it is moving by and how long we have before it totally collapses.