We had a new concrete slab poured in January of 2008 (15'x 30'). Slab is 4" thick over a moisture barrier, no in slab radiant heat, no control joints and at grade level. There is also a man door to the outside. Plan to install ceramic tile in Feb.
The slab is flat and does not have any cracks. Can I just use modified thinset between the ceramic (12x 12 or 13x 13) tiles and the slab or do I need a membrane?