Services & Maintenance: Curtain Walls and Facades
By Richard P. Kadlubowski, AIA
Published in the June 2008 issue of Today's Facility Manager
Cracking at building corners indicates problems with masonry (Photo: Hoffmann Architects, Inc.)
Successful facility management (FM) typically means maintaining a building at the lowest possible cost, operating within realistic annual budgets, and avoiding the high cost of emergency repairs. Whether managing a single building or a multi-building complex, facility managers (fms) must plan ahead for the regular upkeep, necessary repairs, and ultimate replacement of building envelope components.
When it comes to caring for the building façade, a maintenance program is designed to do just that. It is a manageable way of looking at the complexities of the façade system and developing an ongoing, evolving program of care. The program can be used to evaluate existing conditions, identify maintenance, repair and replacement items, and establish a time frame and budget for the work. More importantly, it is a way to help control costs by setting priorities, identifying the most cost-effective scheduling of work, and catching minor problems before they escalate into major repairs.
Common Problems And Effects
Maintenance efforts generally focus on keeping water out of the building and away from essential components. Likewise, repairs most often aim to reconstruct those items damaged by water. It is the management of water, then, that becomes the most important aspect of design, maintenance, and repair projects.
All façade systems are intended to keep water out. However, a proper system is also designed under the assumption that water will get in. Recognizing and accommodating a wall system's built-in water escape routes is critical to successful exterior wall maintenance and repair.
Of the exterior materials in use today, all can (and will) eventually fail. Finish materials such as brick, concrete, and granite can crack; mortar joints can erode or debond; sealant joints can fail adhesively or cohesively and are generally only repaired or replaced after numerous failures have occurred. It is this need for redundancy which is the most important, yet misunderstood, design principal.
Redundancy can be achieved by many different methods. A masonry cavity wall system, for instance, will generally use a through wall flashing and weep system to collect and expel water that enters the cavity. A solid masonry wall, on the other hand, uses multiple wythes (layers) of brick to inhibit water migration and to absorb those small quantities of water which enter the wall. This water is then released through evaporation.
The two wall systems may appear the same on the surface, but each acts differently. A common error made on a cavity wall system is to block or seal the weep holes. This locks water into the wall and may lead to serious problems.
A misconception frequently encountered with solid masonry is that water entering the construction can be stopped with a surface sealer. Since sealers do not bridge gaps (and water mainly enters at cracks and debonded mortar lines), they serve instead as barriers against evaporation for water that penetrates the system. The surface sealer then creates an outward appearance of integrity while interior degradation continues.
Signs Of Trouble
Appropriately designed and properly performed, routine maintenance that is can significantly help extend the life of a façade. However, if executed incorrectly, the very same routine maintenance work may create the unintended consequence of concealing conditions that are prone to spread, or in many cases, actually exacerbate the problem.
This tendency is evidenced by the generous quantity of sealants commonly used to repair defects. Judging by the care and expense with which some cracks are sealed, it is clear that the personnel performing the work is often too preoccupied with keeping water out to question whether water was, in turn, being locked in.
The fm then, having diligently contracted for maintenance, may have a false sense of security about the condition of the building. In such cases, problems are often identified only after they become obvious and pervasive.
To plan and implement lasting solutions, an fm can consult with an architect or engineer experienced in façade rehabilitation to attribute the nature and extent of the problem accurately, develop technically/aesthetically appropriate, cost-effective remedial solutions, and establish probable construction costs.
Troubleshooting depends on recognizing typical problems associated with building materials and types of construction. Here are some general guidelines:
Brick masonry. Brick exterior walls should be checked regularly for failed/aging mortar joints. Debonding, cracked/spalled brick, and efflorescence/water staining are indicators of deterioration.
The basic components of brick veneer wall construction include: the exterior face, the structure or "back-up" (and the cavity between the two), the flashing (which prevents the passage of water into the structure from the joint), and the support angle. Typical causes of failure in this system include absent or inadequate flashing, blocked weep holes, failed or inadequate soft joints at relieving angles, and failed mortar or expansion joints.
Stone and pre-cast concrete. Although some stone construction uses mortar joints, which must be maintained similarly to those found in brick masonry, stone and concrete exterior maintenance is typically centered around the proper care and preservation of sealant joints. Exterior joints must be sealed between individual panels; between windows, frames, and exterior walls; and between any two or more building envelope components. Appropriate sealant selection and application technique are critical to success.
Sealant materials should accommodate differential movement in various building systems and bond properly to different building materials. At installation, consideration should be given to joint width limitations, surface preparation, and exterior temperature fluctuations. During inspections, it is also important to evaluate the integrity of anchor systems in addition to sealant joints.
Glass curtain walls and window systems. A thorough curtain wall or window system inspection should begin with an examination of window gaskets or sealants for splits, breaks, or openings, as these are sources of air and water infiltration. Any gaskets or sealants that have dried, cracked, shrunken, or otherwise exceeded their lifespan should be replaced promptly. Surrounding exterior walls or mullions should also be inspected for signs of deterioration such as rusting or deformation.
Fogged or etched glass may seem unimportant but should not be overlooked. Condensation may be symptomatic of a compromised thermal seal.
Historic and landmark structures. Intricate patterns and decorative elements can present special challenges when maintaining or rehabilitating historic structures. Materials no longer in common use, such as terra cotta, tile, and decorative/ornamental grating, may be unfamiliar to repair or maintenance personnel. Meanwhile, techniques not often encountered in contemporary construction, like narrow masonry joint widths or obsolete anchor and structural systems, present technical challenges.
Landmark status and local building codes may impose further limitations, so the relevant restrictions must be researched and accommodated as part of any façade maintenance or repair effort.
Organizing and planning for façade upkeep as part of a unified building envelope maintenance and repair program is one way to budget for the eventual replacement or rehabilitation of components.
At a minimum, a maintenance plan takes into account the life cycles of various façade materials then schedules maintenance and repair work accordingly. More detailed programs organize inspections, set priorities, and address minor problems before they escalate into fully compromised systems, extending the lifespan of the façade and the building envelope as a whole.
Through the preparation and implementation of a maintenance program, routine care and preservation work can be performed systematically to minimize disruption to building use and avoid unforeseen expenses.
Program objectives. While a building envelope maintenance plan can be organized in any number of ways to meet an fm's specific needs, some of the main outcomes might include:
- Setting a baseline by investigating existing façade conditions. This review should include examination of original designs, drawings, and documentation of previous repairs. A visual inspection of the façade then completes the picture of current conditions and anticipated maintenance needs (conditions outlined under "Signs of Trouble" subhead earlier in this article). A written report of these findings can serve as the framework of the program.
- Identifying existing and potential problem areas. Each issue should be evaluated by priority and urgency. Life safety items, such as loose and crumbling masonry, must be addressed first.
- Establishing a budget and schedule. The plan should include routine maintenance, treatment of potential problem areas, and repair or replacement of deteriorated elements in order of priority. Along with materials lifespan information, the conditions survey can aid in planning for rehabilitation of major components.
- Creating an easy-to-use inspection tool that organizes inspection timetables. Regular inspections identify materials near the end of their service life, allowing for a planned program of repair-and so avoiding unforeseen, expensive emergency repairs.
- Providing a benchmark against which to measure progress in meeting goals. This will help the fm in planning for future inspections.
- Timing façade cleaning. As part of a façade maintenance program, should cleaning be scheduled before or after repairs or restoration work? Because it can be difficult to detect what may need to be repaired on a surface heavily covered with dirt, stains, paint, or other coatings, it may be necessary to clean the façade as part of the investigation phase of the program. Cleaning before performing repairs also provides a clear, sound surface on which to do the work.
However, if pervasive leaks are a problem, it may be a mistake to run the risk of greater moisture intrusion by adding water during cleaning to areas that may already be precarious. In this case, scheduling patching and sealing work to precede cleaning may be the most prudent option.
The program in practice. Ideally, a façade service program should be used in the first year to set future budgets and to identify specific maintenance, repair, and rehabilitation work for the coming year.
In subsequent years, the program can continue to serve as a budget projection tool for upcoming capital expenditures. It will also serve as a benchmark.
Once a year, FM staff should conduct a review of the previous year's work, asking: What work was performed? What was delayed? What is the current status of materials or areas that had been earlier identified as potential problem spots? Should priorities be adjusted? Once these questions have been answered, the plan should be updated to create a record for the coming years.
Façade care as part of exterior envelope maintenance. Because deterioration in one building system can adversely impact other building systems, any program of façade maintenance and repair must be integrated into a larger plan for the building envelope as a whole. Sometimes, observable conditions, like leaks, may appear in the wall area but have a distant source, such as a faulty roof flashing.
To avoid duplicate or unnecessary repairs, fms who have diligently conducted routine inspections and noted water infiltration or other deterioration conditions might want to consult with design professionals experienced in building envelope investigation to determine the underlying cause of the problem. That way, the appropriate remedial work can be integrated into the facility's rehabilitation planning. With a thoroughly researched and actively implemented façade maintenance program as part of a building envelope plan, fms have an invaluable tool to articulate maintenance and rehabilitation goals and to outline the steps necessary to reach them.
Kadlubowski, AIA (email@example.com) directs Hoffmann Architects, Inc.'s Washington, DC office. As vice president and senior architect, he oversees a wide range of façade projects and is experienced at evaluating, maintaining, and rehabilitating all elements of the building envelope.
Do you have an effective exterior maintenance program in place? Share your successes by sending an e-mail to firstname.lastname@example.org.
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