Building panels comprising a locking system for vertical and horizontal locking of a first edge portion of a first building panel to an adjacent second edge portion of a second building panel, wherein upper portions of the first and second edge portions in a locked state of the first and second building panels together define a vertical plane perpendicular to a horizontal plane, which is parallel to a front side and/or a rear side of the building panels,
- wherein the locking system comprises a tongue provided in the first edge portion and a tongue groove provided in the second edge portion, the tongue and the tongue groove being configured to cooperate for vertical locking,
- the tongue groove comprising an upper lip and a lower lip protruding horizontally beyond the upper lip, wherein, in the locked state of the first and second building panels, the tongue is configured to contact the upper lip at respective upper vertical locking surfaces of the tongue and of the upper lip and is configured to contact the lower lip at respective lower vertical locking surfaces of the tongue and of the lower lip,
- wherein the locking system comprises a locking element provided in the first edge portion and a downwardly open locking groove provided in the second edge portion, the locking element and the downwardly open locking groove being configured to cooperate for horizontal locking, said locking element being provided on a strip extending beyond the upper portion of the first edge portion,
- wherein, in the locked state of the first and second building panels, a total horizontal extension of contact between the respective lower vertical locking surfaces of the tongue and of the lower lip extends
- from contact at an inner end portion of the lower vertical locking surface of the lower lip and an outer end portion of the lower vertical locking surface of the tongue
- to contact at an outer end portion of the lower vertical locking surface of the lower lip and an inner end portion of the lower vertical locking surface of the tongue,
- wherein, in the locked state of the first and second building panels, a total horizontal extension of contact between the respective upper vertical locking surfaces of the upper lip and of the tongue extends:
- from contact at an inner end portion of the upper vertical locking surface of the upper lip and an outer end portion of the upper vertical locking surface of the tongue
- to contact at an outer end portion of the upper vertical locking surface of the upper lip and an inner end portion of the upper vertical locking surface of the tongue,
- wherein, in the locked state of the first and second building panels:
- (i) the outer end portion of the lower vertical locking surface of the tongue is provided horizontally closer than the outer end portion of the upper vertical locking surface of the upper lip to the locking element;
- and/or
- (ii) the inner end portion of the lower vertical locking surface of the lower lip is provided horizontally closer than the inner end portion of the upper vertical locking surface of the tongue to the locking element,
- wherein the locking system further comprises outer vertical locking surfaces provided horizontally outside of the tongue in the locked state,
- wherein, in the locked state of the first and second building panels, the total horizontal extension of contact between the respective lower vertical locking surfaces of the tongue and of the lower lip is larger than the total horizontal extension of contact between the respective upper vertical locking surfaces of the upper lip and of the tongue, and
- wherein, in the locked state of the first and second building panels, the upper and lower vertical locking surfaces are offset horizontally such that the upper vertical locking surfaces are provided horizontally closer than the lower vertical locking surfaces to the locking element.