The present invention provides a combination tool for use by an individual workman, without resorting to assistance by another workman, for laying out horizontal and plumb lines in a confined space, such as that found in a shower stall, bathtub enclosure, or fireplace. The invention has a body in the shape of an isosceles triangle. Centrally positioned referencing levels align with the centerlines of each leg of the triangle. The referencing levels are duplicated in order to provide better accuracy of measurement. The tool is of sufficient thickness to allow the removable attachment of a chalk line clip to one of two blunted ends of the tool so that a single workman can extend and snap chalk lines on a surface of interest. A tiler may use the tool of the present invention to practice an inventive technique of laying tile in an efficient and aesthetically pleasing manner.