Structural panel with exterior insulating foam layer

A structural sheathing system, comprising:

• two or more structural panel products, each panel product comprising an exterior face, an interior face, and edges therebetween, said panel products configured to be secured to a building frame with the interior face adjacent the building frame and with respective adjacent edges forming a gap therebetween;
• wherein each structural panel product comprises two layers, a wood-base panel with an outer surface and an inner surface, and an insulation layer with an exterior-facing surface and an interior-facing surface, wherein the interior-facing surface of the insulation layer is affixed to the outer surface of the wood-base panel and the inner surface of the wood-base panel forms the interior face, wherein each structural panel product is secured to said building frame by a plurality of nails penetrating the wood-base panel;
• wherein the insulation layer covers all of the outer surface of the wood-base panel;
• and
• wherein the insulation layer consists of extruded polystyrene (XPS) foam;
• and
• wherein each wood-base panel has flat edges orthogonal to the outer surface and inner surface, and opposing edges of each insulation layer form corresponding joint elements of a modified ship-lap joint, said joint elements comprising an underlap element with an outward-facing main face and an angled face extending therefrom to the outer face of the foam insulation board, wherein the angled face is at an obtuse angle with respect to the outward-facing main face and an overlap element with an inward-facing main face and a drip edge along the outermost edge, wherein the drip edge is not in contact with any part of the underlap element when the joint is formed, and the angled face is not in contact with any part of the overlap element when the joint is formed.