Vertical joint system and associated surface covering system

A vertical joint system for a substrate having an opposed major first and second surfaces, the joint system comprising:

• first and second non-symmetrical joints, the first joint extending along two adjacent sides of the substrate and the second joint extending along two further adjacent sides of the substrate, the first and second joints configured to enable two or more substrates with like joint systems to engage each other in response to a force applied in an engagement direction which is perpendicular to the major surfaces and to enable engaged substrates to be disengaged by lifting a first substrate in a direction opposite the engagement direction to facilitate rotation of adjacent engaged substrates along opposite sides of the first substrate to lie in planes declined from the first substrate and subsequently applying a force in the engagement direction to the second joints of the engaged substrates,
• wherein the first and second joints are each provided with two laterally spaced transversely extending surface portions configured to enable the first joint of one substrate to engage the second joint of a second substrate with the two transversely extending surfaces of the first joint located relative to the two transversely extending surfaces of the second joint to form respective first and second locking planes on an innermost and an outermost side of each joint to inhibit separation of the engaged joints in a direction opposite the engagement direction,
• wherein the first joint extends in the direction of insertion from an edge of the first major surface of the substrate toward the second major surface, and
• wherein each of the transversely extending surfaces of the first joint lie inboard of the edge.