I have been asked to repoint a building that has deeply recessed raked mortar joints. Can I simply repoint the mortar joints or should I grind the brick surface in the areas receiving mortar in order to achieve better bond?
Unless mortar appears on the top and bottom surfaces of the joint or a film-forming water repellent had been applied to the wall in the past, grinding the surface of the brick should not be necessary. Instead, I recommend washing the joints with low-pressure water to remove any accumulated dirt or deleterious substances on the brick surfaces. Fill the joints with prehydrated mortar in three layers, tooling the mortar before applying the next layer. If the joints are less than 3_4 inch deep, they should be ground to achieve that depth before repointing. This repair will change the appearance of the masonry. Be sure the building owner is aware of and agreeable to the change before beginning work.