Connectors for joining adjacent modular floor covering units. Embodiments of the connectors include a film and an adhesive layer coated on one side of the film. To install tiles using the connectors, a first tile is placed on the floor and a connector is positioned so that the adhesive layer faces upward and does not contact the floor. The connector is typically positioned so that only a portion of the adhesive layer adheres to the underside of the tile, leaving the remainder of the connector extending from the underside of the tile. One or more tiles are then positioned adjacent the first tile so that a portion of the connector adheres to the adjacent tiles. In this way, the connectors span adjacent tile edges. The tiles are assembled on an underlying flooring surface without the need to attach them to the floor surface.