An insulated siding member and a method of fabricating an insulating siding member is described. The siding member may include a siding panel, an insulation member and a backing layer. The siding panel may have a cavity that may serve as a molding receptacle to allow the insulating material to be molded directly into the cavity of the remainder of the siding panel. The cavity may also allow for the insulation layer to be applied directly to the panel, whereby there may be no need for an additional adhesive layer to attach the insulation member with the siding panel. Thus, the backing layer may be attached directly to the insulation member. The siding member may have a configuration that may also allow the siding member to be easily engaged with or be interlocked with another siding member to provide for better and more uniform insulation.