Old buildings are beautiful, but old bricks need upkeep. In the photo below, you can see an alleyside brick wall with a mixture of old brickwork and deteriorated mortar joints.
Many of the deep brick joint recesses need to be pointed. Pointing involves not only filling in the voids in the old mortar joints, but also removing the remaining deteriorated mortar at the surface of the wall, carefully. This work has to be done carefully because the old historic bricks are more delicate than modern bricks.
A closer picture of the brick voids is shown below. Those voids allow water to not only enter but also remain inside of the brickwork and seep into crevices within the brick construction, leading to accelerated deterioration. As well, plant and fungus growth can take root and these voids allow a place for rodents and bugs to get into the building assembly.
Modern bricks are made of similar materials, yet still different because today we have heavy automated machinery to refine the constituent sub-component materials. 100+ years ago, sophisticated hydraulic and electric machinery did not exist, the brick manufacturing work was largely done by muscle-power. Also, modern bricks are fired at a high temperature. At the time that outer buildings were built the kilns could not reach the high temperatures of today. That difference means the historic bricks are not just old but also made very differently.
Those difference include a higher permeability, and a lower compressive strength. This is important because proper restoration requires a lime mortar that is compatible to the historic brick.
IDS understands the technical aspects of historic masonry restoration and tuck pointing. Reach out to us if you have questions about your historic DC building.