Floor joists

Dan and Garrett put pink foam weather strip on the top ledge, then 2X4 pressure treated sills on that surface and on the inside lip of the block.

According to the code, pressure treated lumber must always be used when wood is against concrete . The upper sill is held on with flanged anchors that are drilled into the block. The lower one goes through L-shaped bolts that are cemented into the block.

Then a felt liner goes along the inside edge of the block between the 2 sills, and next a 2X12 board sits on the lower sill against the felt around the whole inside perimeter.

Now the 2X12 (on 12 inch centers) floor joists are toed into the sill and the perimeter board, and finally a board is nailed between the joists down the middle of the structure.