Abstract: A tongue and groove construction panel in which the tongue comprises a protruding extension formed on a first edge of the panel. The tongue has a head with chamfered sides that expand from a narrowed tip to a neck having essentially parallel sides. The neck merges into a shoulder portion having chamfered sides that expand to merge with the panel. The groove comprises a correspondingly shaped cavity formed on a second edge. The groove has a head with chamfered sides that expand from a base to a neck having parallel sides that merge into a shoulder portion having chamfered sides that expand to a groove opening. The tongue and groove have adjacent chamfered head and shoulder surfaces in an assembled joint. The chafered surfaces of the tongue are disposed at a more acute angle than the chamfered surfaces of the groove to leave spaces therebetween in an assembled joint.

Abstract: A tongue and groove plywood panel in which the tongue comprises a protrud lip having a triangular cross-section extending along the length of a first essentially convex edge. The essentially convex edge is formed by sloping surfaces that slope away from the junctions of the tongue and the first edge to the upper and lower veneers of the panel. The groove comprises a triangular cavity formed in a second essentially concave edge opposite the first essentially convex edge. The second essentially concave edge is formed with inwardly sloping surfaces that slope inwardly from the upper and lower veneers of the panel to the groove to form a shallow essentially concave channel along the second edge to guide and direct the tongue into the groove.