(a) Much of the streetscape in downtown Zanesville is defined by the upper facades of its buildings. The upper facades provide rhythm and architectural character through the pattern of window openings, type of windows, ornamentation, detail, and roofline treatments. Brick is the most commonly used material on the upper facades in downtown Zanesville.
Some commercial and institutional buildings also feature stone exterior walls and extensive use of stone details. Stone has been used for the sills, lintels and hoodmolds surrounding windows in brick upper facades. Some sills, lintels, and hoodmolds are carved with geometric or floral patterns. Stone masonry is generally left unpainted.
Masonry exterior walls are also found on the sides and rear of downtown buildings. In some cases, the type and quality of the masonry changes from front to side to rear. Higher quality, more expensive and attractive brickwork was commonly used on the streetside facades of downtown buildings. The rear, or sides of a building that would not normally be seen by the public, would be finished in less expensive, more utilitarian brickwork.
Some exterior walls have been painted to protect low-quality brick from the weather. Elsewhere, brick walls were painted to cover damaged masonry or wall alterations. This is more frequently seen in the rear or non-public sides of buildings in downtown Zanesville.
(b) Recommendations for Upper Facades/Exterior Walls.
(1) If cleaning of masonry is undertaken, begin with the gentlest effective technique - try scrubbing with a natural bristle brush and plain water before using potentially harmful and more expensive detergents or chemicals. Consult with a professional cleaner before using more powerful cleaning methods.
(2) Power washing is generally the least expensive method to effectively clean masonry surfaces. Moderate pressure of no more than 300 pounds per square inch should be used. Choose a reliable professional who is familiar with testing and cleaning procedures.
Power washing at moderate and high pressure may remove mortar from joints. Lower pressure water-wash methods should be used in areas where mortar joints and caulking around windows are loose or deteriorated, unless they will be replaced later.
(3) Only as a last recourse should any masonry be sandblasted and then only with the approval of the Downtown Design Review Board. Sandblasting and other abrasive cleaning methods, such as blasting with corn cobs, walnut shells, or glass beads, remove a brick's hard outer crust. When the outer crust has been removed, the brick is unable to withstand the effects of moisture and weathering.
Sandblasting and other abrasive cleaning methods will pit and roughen stone surfaces. This dulls and damages the detailing on the stone surfaces, especially intricately carved stone. Sandblasting also creates a roughened surface area on which dirt will more easily collect. For these reasons, sandblasting of masonry surfaces is not recommended.
(4) Avoid masonry sealers, such as silicone, that will keep out liquid water but not water vapor. Once it penetrates the masonry, moisture can be trapped in the wall and deteriorate both interior and exterior surfaces.
(5) Painted masonry buildings should generally be left painted. The paint may protect soft masonry or cover damaged or unattractive masonry. Masonry that has not been painted in the past should not be painted, especially window lintels, sills, and other details that are stone.
(6) When re-pointing or repairing brick masonry, take care to match the original mortar mix. A mortar with too much cement may be so hard that it causes the softer brick to crack apart. An acceptable mortar mix for softer 19th century brickwork is three to five parts of sand, one part of lime, and no more than one-half part of Portland cement.
(7) A quality masonry re-pointing job includes matching the mortar by color, texture, and composition. Skilled masons took pride in the original tooling, or finishing, of the mortar joints. These joints are an important part of each brick wall's design and should be matched in any re-pointing job.
(Ord. 96-115. Passed 8-26-96.)