I have a 5x20 room off my basement which sits under my front porch. All four walls of the room are cement block all the way up to the ceiling which is the cement slab from the porch above. There is a wood ceiling in the room that has gotten wet from leaks above. Is it safe to remove the wood joists and plywood in that room, fix the leaks and replace it? This doesn't support any weight from the slab above, does it? I assume that it was probably used as the bottom of the form when the slab was poured. Also, when I replace the ceiling, can I attach the ledger board using concrete sleeve anchors? Can these be fastened into the block wall? I'm not sure if they are hollow or have been filled with gravel or concrete. I plan on using the ledger board to fasten joist hanger to and frame back up my ceiling for insulation and wiring. The current ledger is attached with masonry nails. Any thoughts?
Your ceiling may very well be no more than the bottom forms for the slab, but you really need to make sure. Attempting to seal the concrete slab from the underside isn't advisable. Concrete draws moisture, so you will always have a seepage problem after you're finished. I'd suggest sealing the slab on the surface and make sure it quit weeping before proceeding with the remainder of your project. Not all concrete blocks are filled. To secure your ledger board I'd suggest using a lag bolt with a lead spread type toggle. Drill into the block and insert to lead, which will hold the lag bolt. Hope this has been some help. Good Luck
