I bought a 1990 house that has a cantilevered wall. I noticed the basement had a draft from below that wall, so I removed the insulation bats at the sill plate to find fiberglass insulation between the joists beyond the sill plate, but only siding across the bottom of the joists below that beyond the sill plate. In other words, my hand was about 1/8" from sub-zero temperatures, with leaky siding as the barrier. I sealed the joist spaces at the cellar sill plate from sill plate to subflooring and joist to joist with small plywood pieces and caulking. I expected to wait until spring to better seal the cantilevered portion. Spring is here. What I have is shown on some images I posted at http://home.comcast.net/~edlank/BayWindow.html The cantilevered wall is 8' wide by 2' deep. The outside wall extends down almost to the ground. I expected to dig out below it and remove the siding on the bottom across the joists, and the insulation. I was going to seal the joist to end plate joints with caulking, and install foam sheets, with the top one faced, filling the space between joists and building it up in thickness until almost as thick as the joists are high. I expected to cover with outside plywood and recover with siding. Now I have questions. 1) What do I do to avoid animals from making the space below the floor an attractive home? They may eventually decide they should chew through the siding to enjoy the indoor heat in the winter, like I think mice have already done. The posted images show that animals (squirrels?) already are digging out below it and using it as a secure home. 2) If I pour some concrete to avoid tunneling under the space, what should I do to avoid it filling with organic debris and still becoming a wildlife kingdom? 3) If I do something to fill the space, what do I need to do to avoid enhancing termite tunneling through the space into the house? I thank you for considering this.