In screed cables are designed to be fixed to re-bar which has been laid into foil faced insulation (kingspan/celotex) and directly under a minimum 50mm screed, these cables are only normally used in a new extension or conservatory project.
The cable is spaced out according to the desired wattage, normally a minimum of 200w.
In screed cables work differently to the other 2 types as they take much longer to warm the large screed base in which they are installed, for this reason the cable is much thicker at 6mm and produces an output of 17 watts per linear meter.
Once the screed has fully dried the vinyl floor can be installed in accordance to the manufacturers guidelines.
Wooden floors MUST NOT be installed directly onto these cables – they must be covered with a 50mm screed first.
As with any underfloor heating installation it is essential that you have a good level of insulation beneath it to maximise heat output and reduce any downward heat loss.