Our attached garage will become a bedroom/bathroom. The garage sits about 3 ft below the level of the house. On the side of the garage where the house and garage meet, the concrete block foundation of the house extends up. I need to attach a ledger (basically building a deck) a few inches off the garage floor so that plumbing and insulation can be added. My question is, can I attach the ledger to concrete block? I assume the block is hollow. If not, is there another solution? (Could I build a 2x4 wall and attach the ledger to that?) Or run a PT plate along the floor of that wall and use 4x4 posts to act as beams?