Overlay Panel – Benefits Easy Install Overlay Panels Now Available from JCW The time saving and hassle free underfloor heating overlay panel is used as a floating floor (F/F) for heating on a load bearing floor that requires additional insulation. It is suitable for installation on existing ground-slab, intermediate floor or in a cellar space. The pre-grooved overlay panel, available in variousĀ  thicknessesĀ  has grooves for aluminium heat distribution plates.