With our heatbase your looking at 160w/m2 at 2 spacings and 100w/m2 with 3 spacings. It can also be self levelling as we recommend to fill all the spare gaps with either tile adhesive or SLC.@Uheat - Jake can you tell me a bit more about the system, what wattage per m can you run it at with various spacing ? Is it compatable with warm a warm up stat ?