Building panels comprising a locking system

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 the tongue is configured to cooperate with the upper lip at upper vertical locking surfaces and with the lower lip at lower vertical locking surfaces,
• 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, and
• wherein in the locked state of the first and second building panels:
• an outer end portion of a lower vertical locking surface of the tongue is provided horizontally closer than an outer end portion of an upper vertical locking surface of the upper lip to the locking element, and/or
• an inner end portion of a lower vertical locking surface of the lower lip is provided horizontally closer than an inner end portion of an 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, and
• wherein the outer vertical locking surfaces cooperate with each other along a width portion along a transverse direction of the first edge portion, the width portion being larger than 0.10 times a strip width of the strip.