Your brick or stone landmark has withstood tempestuous weather and the test of time. But now may be showing its years. Follow these rules in repairing or brick or stone building.
- There is more to mortar than you think. Mortar is a mix of sand, lime and cement that works by keeping bricks or stones apart. Mortar should expand and contract with temperature and moisture changes. Therefore, it's critical to always use a high quality mortar. For example, the newer Portland cement can be harder than the masonry units. That makes it less elastic, causing cracking and chipping of the bricks during regular freeze/thaw cycles. Refer to Preservation Brief #2, Repointing Mortar Joints.
- Make it a point to repoint properly. When fixing mortar, called "repointing," it's critical to match the original mortar in color, composition, joint width, and tooling. Repointing should be done after cleaning. Always try test patches first.
- Take a breather. Your building needs to breathe. It does this through the masonry, if it isn't sealed artificially. Avoid using sealants. They not only seal your building from outside moisture, they don't let interior water vapor out. If you get started using sealants, your job never ends. They have to be replaced every three years. If you don't, water can seep into areas where the sealant has worn off, get trapped behind existing sealant, and cause damage. Here is an article on clear masonry coatings.
- Don't clean masonry. It isn't necessary. Age and weathering adds character to masonry buildings, and acts as a natural barrier to moisture. If you do decide to clean your masonry building, don't use abrasives. That includes sandblasting and harsh chemical products. Both will destroy the building by removing the protective skin of the brick and stone. Refer to Preservation Brief #1, Assessing Cleaning and Water-Repellent Treatments for Historic Masonry Buildings.