Exterior Wall Maintenance
“Know the Basics – Look Long-Term – Keep it Simple”
So your staff co-workers “stepped back” at last month’s meeting, and left you as the “chosen one” to solve chronic wall leakage problems at several of the corporation’s high rise… and high profile… office buildings. Relax - - - it will be ok - - this doesn’t need to be a “career changing” assignment.
While solving leaks and preserving asset value of exterior wall systems can be challenging, the task is manageable if a few basic principles are remembered and applied.
1. The task is worth undertaking. The exterior skin, insulation, windows and structural support systems of the building are important corporate assets with high replacement values. Their performance is critical to protecting the company’s core business and administrative functions. These systems house and ensure a safe, productive work environment for the company’s employees, vendors, customers and the general public. With rising energy costs and growing focus on indoor air quality and environmental health of the work place; the effective proactive maintenance of these wall systems is becoming more and more critical to building and corporate management. The EPA has estimated an economic loss of “tens of billions” of dollars per year in worker productivity, and health and energy costs related to indoor air quality of buildings. So approach the task with a high sense of purpose and responsibility. The success of your efforts is important to the corporation, its employees and stockholders.
2. As Drucker aptly put it, “you can not manage what you cannot measure!” Any remediation project and/or asset management program must begin with quantifying the task whether it is the number, location and severity of leaks within a building or the quantity, type, age, condition and remaining service life of the various components (curtain wall, insulated glass units, sealant joints, gaskets, cladding panels, panels, anchorage devices) that make up the wall systems.
Begin by establishing a reliable leak reporting/validation process for observed water infiltration problems. The procedure will vary by organization, building size and building maintenance staff availability, but the leak data should be reported to and verified by a specific individual who understands the importance of accurate leak information. At a minimum, the leak report should include: date, time, floor level, elevation (N/S/E/W), specific location (office #), window/wall location (head of 3rd window) and severity (condensation, drips, trickle, continuous flow, serious flood). Accurate, reliable leak data is a critical first step in planning/developing an effective, efficient survey and remediation project. Too often, we have begun our condition assessment efforts with “it leaks everywhere!” when the building only leaked at the heads of the windows on the 7th and 8th floors on the north elevation and at the spandrel panels and floor lines on the 14th, 15th, and 16th floors on the south and east elevations. The cost, schedule and scope of the condition assessment and the design and remediation phases can be greatly reduced and simplified with accurate, reliable leak history data. This data provides a valuable initial understanding of the scope of the problems: Are the leaks isolated? Systemic? Wind dependent? Temperature dependent? Vertically oriented? Growing in severity? This data is important in determining the approach and scope (and cost) of the assessment effort. The scope and focus of the survey should be based upon the nature of the leakage problems, and the type of construction involved. Due to building heights, the exterior wall investigation process can be both expensive and time consuming. A visual review using binoculars from ground level and lower or intermediate roof/balcony levels is a good starting point – but is considered to be cursory. Since visual inspection from ground or adjacent structures is not definitive, except for the most serious distress conditions; lift equipment or swing stages are normally utilized for access to perform inspection, material sampling and water testing activities. The lift equipment, staging and operator cost can represent 20-30% of the survey costs for most buildings. Although full exterior (100%) inspections are sometimes required for forensic or litigation cases, we have been very successful with selective (but detailed) inspections on 1 to 2 swing stage drops (typically 30’ vertical sections of the building exterior) on each elevation. An additional inspection drop may be required to investigate special features or observed distress conditions. Selective inspections generally are 20-30% of the cost of full (100%) surveys. These inspection locations should be selected to access, inspect and test all components of the exterior wall systems at each floor level. In addition to detailed visual inspection and quantification of each wall system component and their relative condition, placement, attachment, expansion provisions and joinery; some of the following testing procedures may be utilized.
- Sample extraction, dimensional and material testing of sealants and gasket materials
- Mil thickness testing of coatings or paint finish
- Rylem tube testing of absorption rates on masonry, concrete, stone or other surfaces
- Compression testing of gasket/glass interface in the window system
- AAMA 501.3 field static water infiltration testing
- ASTM 783 air infiltration test
- ASTM E546-88 test method for frost point of sealed insulating glass
Proper attachment of exterior wall components is critical to performance and safety considerations. The survey should include inspection of structural framing and anchorage conditions at random locations, especially if movement, damage or distress of any wall component is present. This review may involve removal of interior ceilings or wall finishes for access and/or boroscope cameras to investigate demolition and reconstruction costs. In some systems, sectional removal for investigation of construction conditions may be necessary. It is easy to overspend for testing and inspection procedures. Although valuable tools, the location, scope and cost of any testing procedure and system demolition and inspection activities should be validated as relevant to resolving observed condition and problems for each building.