Masonry structures are designed for permanence and durability, with many performing for centuries. However, even the most soundly designed and constructed masonry buildings eventually require periodic maintenance. Environmental factors, weather, chlorides, and pollution contribute to the need for repairs. Neglected masonry may allow water penetration, decrease property value, increase energy expenses, or cause personal injury.
By recognizing the symptoms and taking action, owners avoid the pitfalls of poorly maintained masonry. An owner should hire a qualified inspector who looks for bulges, efflorescence, or the deterioration of mortar joints; spalling of brick, stone, or terra cotta; or parapets that are bowed or have moved away from the building. These conditions are all symptoms of a potentially large problem that should be thoroughly investigated by an experienced masonry contractor to determine the root cause.
There are often great differences between the construction methods of modern and historic buildings. An intimate understanding of these various
construction methods is helpful when determining
root causes and potential repair options.
When an owner of a contemporary structure notices signs of masonry problems, immediate action must be taken toward the identification of the symptom, investigating the root cause for the masonry defect or deterioration, and determining an appropriate repair method. Unfortunately, too often the owner hires an unqualified roofing, waterproofing, or window cleaning company to caulk holes shut and/or water-proof the masonry. This type of approach leads to wasted expense and potentially creates a far greater challenge for a future prudent repair.
Simply put, caulking and waterproofing in most contemporary masonry structures are not going to solve the problem, especially if structural and/or water infiltration challenges exist. Determining the root cause behind the problem is essential.
Common misconceptions: There are many misconceptions regarding masonry repair. Dispelling these myths help owners seek an appropriate, timely repair path and ultimately save money.
It is important to understand that contemporary structures are often constructed as water-managed walls, such as cavity walls. A water-managed wall is designed and built to prevent leakage based on the theory of “control and discharge.” Anticipated and accepted amounts of water that penetrate the exterior surfaces are controlled and discharged.
These walls would have a masonry veneer and a back-up of concrete block or a stud wall with sheathing. In most circumstances, the concrete slab edge is included as part of the masonry back-up. The masonry veneer is connected to these back-up wall materials with a tie system.
The key component to this capture and release theory is the flashing. Flashing redirects the captured moisture and water to the building's exterior through weep holes and along lintels.
Unfortunately, very rarely is the wall system understood by non-masons. A roofing/waterproofing/window cleaning company may first attempt to repair the leak with caulk. The lintels, and possibly the weep holes, may be caulked shut. Depending on the actual construction method of the wall, caulking these areas can make the leak worse and/or trap water in the cavity, where it can accelerate the corrosion of unprotected steel.
Excessive corrosion could create rust jacking and masonry veneer damage, such as spalling or cracking. Also, trapped water can create mold issues and possibly an unhealthy interior environment for the people occupying the space.
Another common mistake occurs when the owner orders spraying waterproofing on a water-managed wall to stop leaks. This “waterproofing” decision fails to understand the fundamental design of a water control and discharge wall system. This practice is a waste of money, and without a real understanding of the waterproofing materials, gives the owner a false hope of a repair's results.
In addition, application of the waterproofing material can cause problems to the landscaping and structure in the form of damaged glass and stained brick work. If the brick is a glazed face, waterproofing may introduce spalling because the process can have a negative reaction with the glazing. Once an owner understands the purpose of cavity walls, he can better realize and appreciate the implications of proper maintenance in regard to the functioning of these systems.
Similarly, cracks in the veneers are often mistakenly repaired with caulk. Without identifying the root cause of cracking, spending money on filling them with caulk is a waste. For example, if cracking is occurring because of an insufficient quantity of wall ties or inappropriate expansion joint locations, caulking does not provide any actual benefit.
Repair process: In many cases, there's simply no way around it. Masonry issues on a contemporary structure often require significant repairs. However, repairs can vary from short-term to long-term solutions, depending on the owner's plans for the building. Regardless of the solution the owner wishes to take, determining the root cause of the problems is an important first step in any repair project.
A sign of masonry problems, such as leaks, cracking, wall bulging, lintel jacking, or just finding masonry pieces on the sidewalk, may indicate larger concerns with a contemporary masonry building design or construction. Today's fast-paced construction schedules often result in insufficient information for contractors to construct properly-working contemporary masonry walls, especially water-managed ones.
This situation is particularly troublesome since there is very little tolerance for design and/or construction error with water-managed walls. As a result, owners are often stuck making an enormous investment in their property in the first couple of years because of a lack of details or material specifications, absence of well-planned details, no constructed mock-up onsite, no follow-up testing in the field, or insufficient inspections by a qualified masonry professional.
To remediate problems resulting from improper design or construction, a qualified masonry contractor begins by interviewing the owner to learn more about the actual problems, as well as his intent. The contractor needs to know if the owner plans to hold the building for a long-term investment or has a short-term commitment to the property and therefore would prefer not to make a major investment.
In the initial phases, a contractor also must examine the original drawings, if available, and perform a visual inspection to determine how the building was constructed. By doing so, a contractor can narrow down the root cause of the problem and develop a proper course of action. A visual inspection should follow the guidelines established by the American Society of Testing and Materials (ASTM) in standard E2270 Periodic Inspection of Building Facades for Unsafe Conditions.
According to this standard, a general inspection can be performed with binoculars at greater than 6-ft from the building to scan the facade and check for out-of-plane displacement of elements, while examing the surface horizontally and vertically. A detailed inspection within 6 ft of a building involves visual observation and tactile evaluation of façade components, including probing and non-destructive testing to observe concealed conditions of wall construction. This level of inspection requires tactile contact with facade elements.
The inspector shall use, at a minimum, the following techniques:
Whether a general or detailed inspection is needed depends on the severity of the problems and the owner's intent. A general inspection is often helpful for narrowing down possible root causes and is especially useful in situations with a short-term owner or one who doesn't plan to make a significant investment in repair. In fact, a general inspection may reveal the wall system type and whether a relatively simple solution is possible, such as re-caulking the window joints.
With information gathered from drawings and an inspection, the qualified masonry contractor is armed with the knowledge to plan a course of action. Most often, a solution involves repointing, wall stabilization, flashing replacement, or installation of new expansion joints.
In some cases, an alternate and less costly repair may be to paint the brick. The theory at work in this repair is that the water-managed wall design is abandoned, and a barrier wall is created with the coating, which then prevents any absorption through the facade. However, since painting changes a building's appearance, this solution doesn't appeal to every owner. When considering painting, it is important to ensure the solution isn't going to trap moisture and create corrosion within the steel components, especially with pieces that are already beginning to rust.
The longest-lasting repair solution usually involves removing the brick, exposing the flashing, repairing or replacing the flashing, and placing the brick back into the building. This solution is usually best for an owner who intends to keep the building for many years.
Masonry repair on older structures requires a particularly high level of expertise. As with a contemporary project, the process for masonry repair on a historic building begins with fact-finding. The contractor must perform a general or detailed inspection to search for the root causes of the masonry problem.
With historic projects, it's important to determine the previous maintenance, cleaning, or waterproofing efforts made to the building. Structure-specific background information regarding previous maintenance enables a contractor to understand the repair history and plan new work accordingly.
Common misconceptions: When it comes to historic masonry repair, problems often arise from contractors who lack experience with the complexities of these older structures. When making repairs that involve historic mortar, the existing type must be identified. A sample should be taken for a professional mortar analysis to determine the blend of ingredients. Whatever the composition, the masonry contractor should know the correct ratio of each material.
In addition to basic color matching, functional concerns involve compressive strength, permeability, and texture. If these items are ignored, additional structural problems may result in the future. Taking a one-mortar-fits-all approach can damage the structure's historical fabric and structural integrity.
Another misconception involves cracking. Historic structures often exhibit extensive cracking and it is usually thought that the problem arises from the building moving or settling. However, it is possible that this sort of cracking comes from another source: embedded steel. In historic structures with masonry-clad steel frames, rusting and expanding steel often cause the cracks. These cracks are usually caulked, but that solution is just a patch for a more serious problem.
It is also commonly thought that old brick buildings remain solid and sturdy forever, requiring little or no maintenance. However, the life expectancy for most mortars is up to 75 years. At the end of its life-cycle, mortar requires repair before moisture and water infiltration create damage to the interior of the building.
Repair processes: Common solutions for historic projects involve repointing the building, individual brick replacement, and wall rebuilding if severe damage has occurred. When embedded steel has begun to corrode, a contractor must remove the masonry, replace or prep and paint the existing steel, and place the masonry back into the structure. Repairing the symptom (pointing, caulking, selective brick replacement, etc.) where embedded steel corrosion is occurring without taking care of the root cause of the corrosion is a decision related to the owner's intended length of possession.
Another consideration is where the cracking is located. Is it over an entry-way or public space? If so, cracks may present a life safety issue to people entering and exiting the structure. If this is the scenario, a long-term solution is more logical. Stripping the façade to expose the embedded steel, treating the corosion, and rebuilding is just one option for this type of repair.
Whether an owner has a contemporary or historic project to consider, the important step is taking action against the root cause of the masonry problems. Annual inspections can reveal issues that demand attention. By maintaining a structure's masonry, owners enjoy the benefits of durability, energy efficiency, and weather resistance for years to come.
Mark K. Howell is a project development manager with Structural Preservation Systems. He is a recognized leader in concrete and masonry maintenance repair and has been involved in the restoration of many historic structures during the last decade. Mr. Howell can be contacted email@example.com.
Adrienne DeRan is a project engineer with Structural Preservation Systems. She has worked on a variety of structures from National Historic Landmarks and Federal buildings to resort hotels and adaptive reuse projects. The co-author can be reached firstname.lastname@example.org.
Structural Preservation Systems is a division of Structural Group. The company is the largest specialty contractor focusing on structural repair, strengthening, preservation, and rehabilitation of masonry and concrete structures. Please visitwww.spsrepair.comfor more information.