AOC is performing maintenance on the northwest terrace granite walls of the Longworth House Office Building [1]. This work includes stone cleaning and replacement of the mortar between the stones.
Work schedule and duration is based on the weather, as cleaning and replacement of the mortar between the stones (pointing) can only be performed at temperatures above 40 degrees Fahrenheit.
These maintenance projects are critical to keeping water out of the building walls and preserving the stone. When mortar and sealant joints are left open and water is allowed to enter the walls, the water can freeze and expand, resulting in breakage of the stone, much like expansion of frozen water in a bottle can cause cracking and breaking of the container. Also, support steel in the walls, when exposed to moisture, can corrode, expand and cause damage to the stone facing.