Abstract: The present invention provides a drain installation kit adapted to maintain alignment of the center of a sloping floor aperture with the center of a drain throughout the construction process. In a preferred embodiment, the kit includes an upper flange that is rigidly connectable to a drain base and multiple sloping guide bars that are rigidly connectable in a radial fashion to the upper flange. A user can use this preferred embodiment by assembling it, adding cementitious material between the guide bars, and making an upper surface of the cementitious material flush with a top edge of the guide bars. Embodiments of the present invention provide a variety of advantages over conventional drain installation kits. For example, many embodiments provide improved functionality, many embodiments are easier for do-it-yourselfers to use, and many embodiments can be manufactured more efficiently.