I want to raise the living from to match the rest of the house. It about 5" lower. The house has concrete sub flooring covered by carpet and tile. I had first thought about just pouring concrete since the doors and walls were all in the same plane as the rest of the house. Just like filling a hole. But I'm concerned by the weight of the concrete on the existing floor. Another concern is how to bond the new concrete to the old. There may be more. I sure could use some advice.