I have a two story house where the stairwell ends in a small room where the front door and the door to garage are accessible. This lower area is a 4" concrete slab that I poured monolithically with the garage floor. I want to tile this little 'mud room' but I'm not sure if I need to put down 'Hardie-board' over the concrete. Yet the house is in earthquake country (Northern Calif. coastal area) and I have already noticed a few hair line cracks. If I do use 'Hardie Board' would a liquid nails type glue hold down the Hardie Board?
Any thoughts on this would be appreciated, thanks.
First check to see if the concrete is smooth and level.
If it is, then you can install directly over the concrete. No need for hardie board or any other cementitious backer-board.
Make sure that the concrete is properly cleaned prior to the tile work.
Now, on the other hand, if you have hair-line cracks in the location of your future project, you should seal these up and consider using a tile underlayment membrane like Ditra.