A meandering crack is often difficult to follow accurately with cutting equipment. Portions of the crack may occasionally be missed, resulting in two adjacent channels. This presents the dilemma of whether to seal both the cut and uncut crack segments or to cut the missed crack segment and seal both reservoirs. A similar dilemma arises with secondary cracks along the primary crack.
Routers and saws are usually equipped with controls for varying the depth of cut, and the width setting can normally be adjusted manually. Backer rod can be placed in deep reservoirs (25 to 38 mm) to a depth that allows for the desired shape factor. This depth normally varies between 12 and 19 mm. The backer rod should be about 25 percent wider than the width of the crack reservoir for it to maintain its vertical position and provide proper shape for the material.
