Working on a kitchen remodel in SW Portland we removed a tile floor in preparation to put in a new red oak floor. The new oak floor will match the rest of the house. When we got to the ares of the floor just below the blue wall we found a hole in the sub floor filed with cement. Under the cement a few rows of bricks from the base of what used to be chimney. With a bit of additional framing and a few pieces of 3/4 plywood the sub floor was patched and ready for the new hardwood floor.