We periodically erect scaffolds for our customers. Above 20 feet in height, we tie the scaffolding for stability per OSHA regulations. We use threaded drop-in concrete expansion anchors to anchor into masonry walls. Where should we drill the holes for these anchors in head joints, bed joints, or into the masonry units themselves?
Install the drop-in anchors into the bed joint at the intersection between the bed joint and the head joint. Unless the masonry units are solid, the drop-in anchors will not set properly within the units themselves because of the cores. Depending on the quality of the workmanship in the wall, head joints may not be completely filled with mortar. At the intersection between the head and bed joint, even an anchor as large as 5_8 inch in diameter can be installed with minimal damage to the masonry units. Recess the anchor at least 1_2 inch from the face of the masonry so it can be covered with mortar when the scaffold is removed. Use stainless steel drop-in anchors to prevent future corrosion damage to the masonry near the anchor.