Adhesive threshold bar

1. A floor or wall transition element comprising:

an elongated profile; and

two folded sheets each defining opposing first and second major surfaces and each having an adhesive layer on the corresponding first major surface, the folded sheets each defining longitudinally-extending first and second strips, wherein the second major surface of each of the folded sheets is free of adhesive;

wherein relative to an upright orientation of the floor or wall covering transition element in which an upper surface of the elongated profile is above a lower surface thereof, the first strips are positioned under the elongated profile and the corresponding adhesive first major surface of the first strips is opposite to the elongated profile, and the second strips are each glued to the lower surface of the elongated profile by the corresponding adhesive first major surface;

wherein the floor or wall transition element is capable of being either (1) fixed to a flooring at the junction of two floors of different natures or (2) fixed to a wall at the junction of the wall and another surface of a different nature.

2. The transition element of claim 1 , wherein each of the first strips are, in cross-section, offset towards the inside of the elongated profile with respect to edges thereof.

3. The transition element of claim 1 , further comprising an open longitudinal guide rail projecting from the lower surface of the elongated profile.

4. A floor or wall transition element comprising:

an elongated profile defining an upper surface and a lower surface; and

a folded sheet defining two longitudinally extending first strips each having an adhesive layer, and a second strip, the first strips located at opposite sides of the second strip, respectively;

wherein relative to an upright orientation of the floor or wall transition element in which the upper surface of the elongated profile is above the lower surface, the first strips are positioned under the elongated profile such that the corresponding adhesive layer is opposite to the elongated profile, and the second strip is glued to the upper surface of the elongated profile;

wherein the floor or wall transition element is capable of being either (1) fixed to a flooring at the junction of two floors of different natures or (2) fixed to a wall at the junction of the wall and another surface of a different nature.

5. The transition element of claim 4 , wherein the second strip is a coating of the upper surface of the elongated profile.

6. The transition of element of claim 4 , wherein each of the first strips are, in cross-section, offset towards the inside of the elongated profile with respect to edges thereof.

7. The transition element of claim 4 , further comprising an open longitudinal guide rail projecting from the lower surface of the elongated profile.

8. The transition element of claim 1 , wherein each of the folded sheets includes a support sheet coated with a thin glue.

9. The transition element of claim 8 , wherein the support sheet comprises a material selected from the group consisting of paper and plastic.

10. The transition element of claim 9 , wherein the elongated profile is aluminum.

11. The transition element of claim 1 , wherein the upper surface of the elongated profile is convex and the lower surface of the elongated profile is concave.

12. The transition element of claim 1 , wherein the elongated profile is not folded on to itself.

13. The transition element of claim 1 , wherein only a single fold line is defined in each of the folded sheets.

14. The transition element of claim 4 , wherein the elongated profile defines opposing, first and second edges, and further wherein a first one of the first strips is located at the first edge, and a second one of the first strips is located at the second edge.