Masonry Magazine August 1988 Page. 28
Terra Cotta Primer
continued from page 14
but telltale signs of underlying problems that are best interpreted by an experienced individual with the full support of a testing laboratory. Even in cases where the problems appear obvious-broken and falling blocks, characteristic cracks, etc. it is best to get the advice of an expert who can explore the full extent of the damage, determine its root causes and suggest a plan of remedial action.
The plan must be comprehensive. Inadequate repairs or the use of improper materials may actually hasten the deterioration and failure of the terra cotta.
The consultant will use a combination of visual inspection and a variety of testing procedures to determine the current condition of the terra cotta.
He will be looking in particular for missing units, deteriorated mortar, large cracks, spalled glazes, discolorations and other major signs of both material failure and its underlying causes.
Testing Procedures
There are a variety of available physical tests that are regularly conducted in the field. An experienced consultant can often determine the condition of a terra cotta unit
Below-In many of the highrise buildings built from 1910 to 1930 natural stone was used on the first few floors and then terra cotta was used on the remaining floors.
simply by striking it with a wooden hammer and evaluating the tone that results. The use of metal detection equipment will help to locate the presence (or absence) of metal hangars. Stress tests, which may be highly sophisticated, will gauge the degree of tension the terra cotta is under.
The field tests may be backed up with laboratory tests. These will determine such critical factors as the current condition of the tile body, and whether or not it is actively deteriorating.
Consultant's Recommendations
With the information from the visual inspection, field testing and laboratory results, the consultant can be expected to predict the long-term viability of the terra cotta. He will make specific recommendations as to which pieces need to be repaired or replaced. His recommendations should include alternatives for replacement.
He will pinpoint the sources of stress and/or the moisture penetration problems that may exist, offer solutions to alleviate them and recommend an ongoing maintenance program.
Repair or Replace?
Short-term budget considerations will often encourage the building owner to attempt to patch or repair existing terra cotta rather than replace it. However, industry consultants are nearly unanimous in agreeing that the replacement of a badly damaged unit is usually preferable to an attempt to repair it.
While the initial expense of a repair may be less, it should be kept in mind that the repair material will weather differently than the original. Aesthetically, it will soon cease to match the original terra cotta. If the patching materials are not fully compatible with the original, they may actually become a source for more widespread deterioration and failure.
Replacement Options
There are a variety of options available to building owners who have determined that they will completely replace failed or potentially failing terra cotta units. Most desirable, perhaps, is the use of existing terra cotta material from other parts of the building to effect the repairs. The replacement material will match the original in color, texture and technical characteristics.
The owner may also elect to have exact duplicates of the failed pieces custom-manufactured in terra cotta or in a variety of substitute materials.
Substitutes are often considered an attractive alterna-