A
quadrilateral building panel (1) has a major plane, and two major side surfaces (2) which are at least substantially parallel to the major plane, the thickness (t) of the panel (1) being between the major side surfaces (2), the panel (1) having four major edge surfaces (3, 4, 5, 6) substantially forming a perimeter of the panel (1). The building panel (1) has at least one engager first portion (7), the engager first portion (7) having a latch catch member (22) and an axis of rotation (23) for the latch catch member (22). The building panel (1) also has at least one engager second portion (8), the engager second portion (8) comprising first and second parts (32, 41) situated respectively at the two major side surfaces (2) and a third part (28) situated at the said major
edge surface (5, 6), the third part being adjacent to the first and second parts. Each of the first, second and third parts of the engager second portion (8) has a latching surface (36,37) configured to be engaged by a latch catch member (22) of an engager first portion (7) of an adjacent like building panel. Each major
edge surface (3, 4, 5, 6) has either at least one engager first portion (7) or at least one engager second portion (8), at least one major
edge surface (3, 4) having at least one engager first portion (7) and at least one other major edge surface (5, 6) having at least one engager second portion (8). One major edge surface (3) is spaced from the axis of rotation (23) of the closest engager first portion (7) or the centre of the latching surfaces of the closest engager second portion of an adjacent major edge surface (4) by a distance being the sum of a predetermined distance and the panel thickness (a + t). The opposite major edge surface (5) is spaced from the axis of rotation of the closest engager first portion (7) or the centre of the latching surfaces of the closest engager second portion of the said adjacent major edge surface (4) by a distance being the sum of the predetermined distance and double the panel thickness (a + 2t). The axis of rotation (23) of the at least one engager first portion (7) or the centre of the latching surfaces of the at least one engager second portion at each of two adjacent said major edge surfaces (3, 4) are aligned with the axis of rotation of the at least one engager first portion or the centre of the latching surfaces of the at least one engager second portion (8) at the respective opposite major edge surfaces (5, 6), where each major edge surface (3, 4) has the same number of engager portions as the major edge surface (5, 6) it is opposite to.