Abstract: The combination of a support having an upwardly facing surface, a transition strip on the support, and first and second layers against the upwardly facing support surface. The transition strip has a single piece that defines a horizontal wall, an upright wall projecting angularly and upwardly away from the horizontal wall and having first and second oppositely facing surfaces, and a cap on the upright wall. The cap, horizontal wall and first surface on the upright wall cooperatively define a U-shaped first receptacle opening in one horizontal direction. The cap, second surface on the upright wall, and upwardly facing surface on the support cooperatively defining a U-shaped second receptacle opening oppositely to the one horizontal direction. The first layer is placed against the upwardly facing support surface and has a first edge that nests in the U-shaped first receptacle. The second layer is placed against the upwardly facing surface and has a second edge that nests in the U-shaped second receptacle.