<p>An improved composite structural panel and method of fabrication are provided. In one embodiment, the panel generally includes two outer layers or sheets arranged in substantially facing relationship to each other and an intermediate layer spacing the outer layers apart. The intermediate layer includes a generally rigid stiffening or reinforcing core that preferably is bonded to outer layers to form a unified composite structure. In one embodiment, the core has an open structure defining a plurality of open cells 15. An insulating material is preferably disposed in the cells, and in one embodiment is a rigid foam that structurally reinforces the core 14 and strengthens the panel.</p>
