We have just bought an ex council house and I wanted to have the kitchen and dining room floor at the same level so we could have the same flooring running throughout. It seemed silly to me to raise the dining room floor so I started ripping up the kitchen floor instead. I took up what I thought was a rather deep levelling compound but have just read on another thread that is was mastic asphalt and was a damp proofing thing. What are my options now? is there something else I can use to damp proof the floor? something thinner maybe? we are already on a very tight budget and I am very worried I have just cost us an awful lot of money. 
I hope someone has an answer, thanks.
I hope someone has an answer, thanks.