I needto raise the level of my concrete slab to bring it up to the level of adjacent rooms carpet and Hardwood flooring. The amount I need to raise it is approx 3/4". I bought hardie cement backer board, but I read this is not a good idea. Although it was what was suggested by our local lowes, we use the hardie backer board and thin set motar to attach it to the concrete slab. I plan on putting ceramic tile over it.

I am at a loss. I have had problems using self leveling compounds in the past, and also though this would be too thick for SLC.

Any good ideas?