Floor covering and locking systems

1. A locking system for mechanical joining of floorboards, in which the locking system of joined ones of the floorboards has a horizontal plane which is parallel to a front side of the floorboards and a vertical plane which is perpendicular to the horizontal plane, wherein the locking system has mechanically cooperating locks for vertical joining parallel to the vertical plane and for horizontal joining parallel to the horizontal plane of a first joint edge and a second joint edge, said locking system is configured to be joined by angling, a vertical lock of the cooperating locks comprises a tongue which cooperates with a tongue groove, and a horizontal lock of the cooperating locks comprises a strip provided with a locking element with a locking surface which cooperates with a locking groove, said strip protrudes past the first or the second joint edge, wherein the first and the second joint edges have upper and lower joint edge portions, the upper and lower joint edge portions each having at least a vertical wall and being positioned between the tongue and the front side, the upper joint edge portions being closer to the front side than the lower joint edge portions, and wherein the strip has an upper surface extending from a lower wall of the tongue groove to the locking element, the upper surface extending past the lower joint edge portion in the second joint edge, and wherein, when the floorboards are joined and pressed towards each other, the upper joint edge portion in the first joint edge overlaps the lower joint edge portion in the second joint edge such that the upper joint edge portion in the first joint edge is in a different vertical plane than the lower joint edge portion in the second joint edge.

2. A locking system as claimed in claim 1 , wherein when the floorboards are joined to each other in a locked position, the upper joint edge portions are spaced from each other to provide a visible gap on the front side of the floorboards.

3. A locking system as claimed in claim 2 , wherein the upper joint edge portion in the first joint edge overlaps a lower joint edge portion in the second joint edge when the floorboards are subjected to a tensile load.

4. A locking system as claimed in claim 3 , wherein the upper joint edge portion in the first joint edge overlaps a lower joint edge portion in the second joint edge when the tensile load is 100 kg/m of joint edge.

5. A locking system as claimed in claim 1 , wherein the upper joint edge portion in the first joint edge overlaps a lower joint edge portion in the second joint edge when the floorboards are subjected to a tensile load.

6. A locking system as claimed in claim 5 , wherein the upper joint edge portion in the first joint edge overlaps a lower joint edge portion in the second joint edge when the tensile load is 100 kg/m of joint edge.

7. A locking system as claimed in claim 1 , wherein there is an average play of at least 0.1 mm when the floorboards are subjected to a compressive or a tensile load of 200 kg/m.

8. A locking system as claimed in claim 1 , wherein the upper joint edge portion in the first joint edge is adjacent to the front side and extends from the lower joint edge portion in the first joint edge, and has a lowest part which, when the floorboards are joined together, is positioned closer to the front side than to an uppermost part of the tongue.

9. A locking system as claimed in claim 8 , wherein a minimum joint opening between the upper point edge portions in a locked state of the floorboards is greater than half of a maximum joint opening between the upper joint edge portions in the locked state of the floorboards, the minimum joint opening and the maximum joint opening each opening at the front side of the floorboards.

10. A locking system as claimed in claim 1 , wherein the floorboards have a surface layer made of wood, and the upper joint edge portions are formed in the surface layer.

11. A locking system as claimed in claim 1 , wherein the floorboards have a surface layer of laminate and a core of fiberboard-based material, wherein the upper joint edge portions are formed in the surface layer and in upper portions of the core next to the surface layer, wherein a vertical extent of the upper joint edge portions is less than 0.1 times a floor thickness of the floorboards.

12. A locking system as claimed in claim 1 , wherein the upper surface of the strip is parallel to the front side of the floorboards.

13. A locking system as claimed in claim 1 , wherein

the lower joint edge portion of the first joint edge comprises a joint groove having a first depth in the horizontal plane and the lower joint edge portion of the second joint edge comprises a joint projection having a second depth in the horizontal plane,

the joint groove includes an upper wall, a lower wall, and a side wall connecting the upper and lower walls,

the joint projection includes an upper wall, a lower wall, and a joint tip connecting the upper and lower walls, and

the second depth is greater than the first depth such that, when the floorboards are joined and pressed towards each other, the side wall of the joint groove of the lower joint edge portion of the first joint edge contacts the joint tip of the joint projection of the lower joint edge portion of the second joint edge, the entire upper joint edge portion of the first joint edge and the entire upper joint edge portion of the second joint edge are spaced from each other along the vertical plane.