The WIB boards will save you money by acting as a very efficient thermal barrier. Heats up times in our testing facility were cut down from 2.5 hrs. to just 25 minutes. With a 78% fast ramp-up time, your system will save you 71% in electrical usage.
Ultralight can not be layered because the thickness will double of amount of movement under the tile which means the floor will not meet the declared wear ratings. Pro Tip: If you need more height, use leveler to prepare the floor as needed followed by Ultralight.
All surfaces should be thoroughly cleaned of all dirt and debris. When installing over an existing concrete base, it is important to remove all traces of existing finishes, contamination, etc. to allow for a clean surface.