Backing, in thisgallery I show how I have secured backing, with all treads, Jbolts,lags etc.

This is one way to do a doorway or window

Jbolt is pre drilled into the wood waiting for concrete to be poured to lock it in!

2 x 4 backing, for drywall, for peg board, nailers, cabnets,anything to mount to, if you wanted.Below photos show install before concrete.

I have mounted steel plates with bolts welded to the inside,placed into the cell for concrete. Then the steel door can be welded right to that steel. (gun safe)

 2x4 backing, cut a grove (seamsof 2 block that come together) cut it the thickness of the board and a little over. Nail or screw the back of the board and let the nails or screw hang out, place in the cut slot and foam. When the concrete pours, it will lock that board in!