Supplemental heat can be addressed by changing the spacing on cable installs. Floor location in the house is very important when considering adding supplemental heating to a floor. For example: If heating a second story floor, over a heated space, cable at 4" spacing can be used. The same type of heating over an unheated space would probably be done with TempZone Flex Rolls or TempZone Cable at 3" spacing. All heating is considered supplemental unless a heat loss calculation is done.