Many people wonder if it is worth insulating under floorboards and the answer is that yes, it definitely is. Insulation boards are ideal for use with electric underfloor heating as they prevent the heat from the heating system escaping downwards to the subfloor. The Warmup Insulation Boards do not let the heat pass through from the heater to the subfloor. Therefore the heat gets pushed upwards, onto the floor surface where you want the heat to go.