The present invention relates generally to plumbing control joints in masonry walls, and more particularly to a method and apparatus for plumbing a control joint in a brick wall. Bricks are laid typically to form an outer building surface and during the process of laying bricks it is common to space vertical gaps periodically in the brickwork. These gaps are known in the art as control joints as they control cracks from forming in masonry walls by relieving stresses within the wall. Brick walls are subject to cracking for many reasons such as temperature or shrinkage induced changes or load stresses. Regardless of the reason, cracks must be controlled to maintain moisture resistance and appearance. Control joints allow segments of a structure to move independently of each other while retaining the integrity of the structure. A common type of control joint that is utilized in masonry walls comprises a vertical “seam” that separates horizontally adjacent sections of masonry material (e.g., brick). The thickness and placement of the control joint will vary depending upon the type of wall, climate, etc. The resulting wall is in essence, two independent wall sections separated by a thin vertical seam. The seam may be filled with foam plastic and later covered by caulking on the exterior surface. The outer surface of the brick wall is referred to in the art as the “brick skin.” While the use of control joints improves the stability of a structure, their use creates new challenges for the masons laying the brick. In particular, as the wall is being erected, the mason must ensure that each control joint is plumb, i.e., at a right angle to level ground. Failure to properly plumb each control joint may compromise the building structure and the appearance of the brick skin. Given the widespread use of control joints, the process of precisely installing control joints can add a substantial amount skill, time and cost skill to a project. Accordingly, a need exists for a low cost device that will facilitate the process of plumbing control joints in a masonry structure.