(A) Lime-based mortars are found in historic masonry buildings. Portland cement, although commonly used today, is destructive to historic masonry because Portland cement mortar is much harder than the masonry brick or stone. Therefore, when the wall expands and contracts with changes in temperature, the bricks “give” rather than the mortar. The visual impact is also an important consideration as Portland cement mortars take on a different color than masonry. Another consideration is the fine craftsmanship that is found in the joint profiles of historic masonry buildings.
(B) Design guideline. Materials used in re-pointing shall match the appearance and properties of the original as closely as possible. This includes the color of the mortar and the joint type.
(Ord. 14, 2011, passed 10-3-11)