A building that has been open to weather for some time may have more severe deterioration that would require substantial rebuilding. Whenever new brick or stone is used to rebuild part of an existing structure, the new materials (brick or stone and mortar) should match the original material as closely as possible, in color, size and composition.

Repointing of historic masonry walls must match the original mortar in color, texture, composition and Joint profile. Mortar for historic buildings should be relatively soft, and contain no more than 20% Portland cement. This will produce a mortar that is durable, but sufficiently soft to protect historic brick.

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Tie-rods on masonry walls were often placed during construction and sometimes installed later to correct a structural problem. The system consists of an iron rod with a turn buckle running in the joist space, usually between bearing walls, which is connected to a decorative plate on the outside of the building. Existing tie-rods and plates must not be removed; new rods may be added to help correct a failing structural condition. Painting of unpainted masonry walls is not acceptable under the Standards. Those buildings which have been previously painted need not have the paint removed, unless it is in a deteriorated condition. Once removed, however, the walls should be left unpainted.

Masonry cleaning-while not a requirement-is recommended, especially if a building has been previously painted. Changing the color of a facade alters the building's original character and obscures the pattern of mortar joints. Cleaning can give the surface of a building new life by removing pollutants, paint and tar, and restoring the natural qualities of the brick or stone. Cleaning should be done:

- by using low pressure water cleaning (not more than 600psi)

-by using gentle detergents and a natural bristle brush

- never by using a metal bristle brush

- never by using abrasive sandblasting

In some instances, masonry cleaning with water is not sufficient to remove stubborn paint or stains. Chemical cleaning with a cleaner low in acid may be appropriate in these cases. Care should be taken not to harm the brick.

Occasionally, removal of paint from a building facade may reveal patches of badly-matched brick from prior repairs. If the repair is really unsightly, a masonry stain may be applied to that area, to bring its color into conformity with the rest of the building. These stains are water-permeable, and semi-transparent, so that the appearance of the brick is not obscured.

Openings: New openings on historic buildings may not be made on street facades. New openings made elsewhere on the building should be of similar proportions and details (matching lintels, sills, etc.) to the original openings.

Masonry openings on historic buildings should be closed or shortened only on non-visible facades. Closures must be in brick, recessed a minimum 2 inches from the facade plane. Windows to be shortened should have the original sill raised and the area beneath infilled with recessed brick.