Provided is a composite joint comprising a pair of composite panels each defining a composite panel thickness and having an inner face sheet and an outer face sheet sandwiching a core panel therebetween. The core panel defines a constant thickness portion and a ramp portion along which the core panel tapers to a reduced thickness portion. The outer face sheet is thickened in the area of the reduced thickness portion. The core panel includes a plurality of cells extending between the inner and outer face sheets. The cells within the reduced thickness portions are filled with a filler material. The cells within the ramp portions and constant thickness portions are filled with aerogel. A primary splice plate extends across the reduced thickness portions. Mechanical fasteners extend through the outer face sheet and into the primary and secondary splice plates. A themal barrier compound covers the primary splice plate.