Published in the November 2008 issue of Today’s Facility Manager
There is a great deal of information supporting the fact that planned/preventive maintenance (PM) is key to performance and longevity for any building component. Every facility manager (fm) knows that an effective PM proge reram helps balance availablsources against degrees of potential risk and improves financial results by reducing total cost of ownership (TCO). This basic tenet is especially true in the case of PM as a cost-effective tool to manage roof performance.
When it comes to roofs, “out of sight, out of mind” thinking often prevails, since this facility component is not always viewed as having the same risk level as others. PM programs for roofing are often sacrificed in favor of other maintenance budget initiatives; yet, in the long run, the payback for the facility is every bit as beneficial. When a roof failure occurs, it can affect critical space and operations, and the results can be costly.
Low Voltage Testing Pinpoints Leaks
By Alicia Hexham
When it comes to roofing, the integrity of the waterproofing membranes in the assembly plays a major part in determining if a project is deemed a success or failure. This is why most facility management (FM) professionals require confirmation that the membrane is watertight before all of those involved in the project are able to sign off on the installation.
There are several ways to test the integrity of a roofing membrane, and some are more intrusive than others. A common method has been flood testing. However, this approach presents some challenges, including the inability to test sloped or vertical walls; being expensive and time consuming; allowing pinhole and minor seam voids to escape detection, potentially causing future mold growth and structural delay; and posing structural concerns due to the weight load of standing test water.
One alternative is low voltage testing. This approach represents a more accurate and less expensive way to perform integrity testing on a roofing membrane. Originating in the UK and other parts of Europe, low voltage testing was introduced to the United States around 2000 and is used as a way to identify potential and active leaks in a roof.
How It Works
Low voltage integrity testing creates an electrical potential difference between a conductive structural deck and a non-conductive membrane. Three components are needed for a low voltage test: a grounded structural deck, a non-conductive membrane, and a spray of water (or in the case of an existing green (garden) roof, existing moisture within the overburden is used).
An electric field is created in the roof by positively charging the membrane with low voltage equipment, using the negative charge from the grounded or earthed structural deck, and applying water. If the membrane is watertight, the electricity is isolated and does not create a ground fault connection (see diagrams). If there is a breach in the membrane, the positive charge will be unable to locate the negative charge and, therefore, will create a “vector” (a ground fault connection) through the breach.
Using low voltage testing, technicians are able to locate the vector in new or existing roof assemblies. Flood testing, on the other hand, is limited to pre-overburden testing and is not pinpoint accurate.
When Can It Be Used?
Low voltage testing can be used on both a newly installed membrane or on an existing roof. In the case of a new roof, this testing is a proactive approach to ensuring the membrane is watertight prior to the overburden being placed and that repairs made to the membrane are sound. Also, if the conductor wires used in the testing are permanently installed, this can also enable continual retesting through the life cycle of the roof. For existing roofs, low voltage testing enables fms to troubleshoot for breaches or test for integrity prior to the expiration of the membrane’s warranty.
Low voltage testing can be performed on a variety of roofing systems, including: garden roofs, roofs with or without ballast, roofs with paving stones, non-insulated and insulated, inverted, parking garages/decks, pond/water containment liners, and vertical walls.
Leaks in waterproofing membranes can occur for many reasons, including improper installation, mechanical damage from other trades, or simply long-term wear and tear. Small punctures, membrane splits, or mechanical damage can result in wet insulation, mold growth, and interior damage. Low voltage testing can find such small breaches before they become active and and pose a threat to a facility. n
Hexham is a project manager for International Leak Detection (www.leak-detection.com), a Markham, ON-based provider of low voltage integrity testing.
Leak Repair Is Often Too Little, Too Late
Leaks are caused by a myriad of issues that are usually only discovered when a service crew performs a thorough investigation. Maintenance delays can increase damage and repairs, reducing roof life.
Leaks that are discovered for the first time when water enters a facility are among the most common problems related to roof performance. By the time that happens, repair needs are often significant, with the added possibility of business interruption and internal damage.
The potential threats and/or costs from a roof leak are numerous. These include emergency (temporary) repairs, damage to interior finishes, structural problems, harm to inventory or equipment, damage to roof system itself, mold remediation, loss of R-value, business interruption, and permanent roof repairs.
Roof warranties (from either the installer or manufacturer) cover repair costs to stop an active leak, but they do not apply to related damage that may have occurred from those breaches. As such, these repairs (which are reactive measures) are not a replacement for proactive roof PM programs. PM targets likely areas on a roof where defects will be corrected with a minor, less expensive repair.
Roof systems require regular maintenance, and manufacturers often mandate this to keep warranties in effect. Fms can follow an industry accepted PM process that includes an initial roof survey to gather baseline information, written documentation and diagrams, and posted CAD drawings and photo documentation that are electronically tracked and accessed. A condition report is then generated, based on baseline data.
Armed with this information, fms can prioritize to weigh deferred repair concerns across their facilities, set a repair strategy, and factor in all capital replacement priorities to create a plan for a five to 10 year period. The plan should call for deferred capital projects to be reviewed for repair or other life extending options.
Repairs should be performed on sections of the roof designated in a yearly plan. Annual or semi-annual visits should be scheduled to keep current with PM measures and to ensure the data on roof conditions is up to date.
Preventing A Problem
A PM plan should follow several basic principles.
Roof inspection. This includes a visual survey of the exterior condition of the roof and related sheet metal work. In addition, the servicer should inspect the status of wall panels, brick dividers, parapets, and roof protrusions.
General upkeep. Debris should be cleared from the roof surface, gutters, interior drains, and through wall scuppers.
Maintenance. As required, servicers should recaulk open metal flashing, top off pitch pans, reseal suspect mechanical and perimeter base flashing openings, and secure drain clamps and vent pipe rings.
Annual report. Service providers should give fms an annual outline of the work they have performed along with a general condition statement; this statement should include the current estimated roof life. Updated roof drawings and related photographs should be stored in an electronic file.
Inheriting A Roof, No PM Plan
What about an fm who takes the reins of a facility where no PM plan has been initiated? In trying to transition from a reactive to a proactive system of roof maintenance—where there has been no budget for PM and there are too many problems to resolve using corrective action—it is even more important to set priorities and follow a plan to move forward toward PM.
Active leaks should be the first priority, since those will likely cause additional damage to a roof system and related areas. Because these priority repairs impact roof conditions and performance, these actions will help protect the current roof from further deterioration and eliminate the majority of leaks.
Next up is removal of problematic or failing roof areas. Fms should spend capital dollars where the funds will have the greatest impact, not solely based on the age of a component or other single factor. Removal of failing areas will prevent further spending on repairs that offer a low, or even negative, return on investment.
The third step is tackling the lower priority (non-leaking) roof deficiencies and performing regularly scheduled PM activities. These actions preserve the current condition of the roof, bringing it into a more predictable and maintainable condition. This step also begins the process of proactively limiting future leaks into the building.
The fourth step is to replace aged roof assets, thus reducing or eliminating the reactive and costly spending that often takes place late in the roof life cycle. Timely and systematic replacement of older and weathered assets helps to preserve future capital budgets.
The fifth and final step is to begin repairs, renovations, and upgrades to current roof membranes and components. These actions extend roof service life and reduce future capital spending in the short-term by pushing out the costs of currently projected replacements in the next three to five years. This also reduces future long-term spending, since the average cycle of roof replacement is extended.
Regardless of what stage of roof maintenance planning an fm is in, it will always be true that PM is a smarter and more cost-effective measure to take than reactive spending. The sooner an fm can transition from reactive to proactive spending for roofing components, the better off those buildings will be.
Sabol is vice president of TectaService, Tecta America Corp. based in Skokie, IL. With 30-plus years of experience, he manages the company’s comprehensive roof service and planned maintenance programs. Flickinger is strategic accounts manager at Tecta America and has more than 15 years of experience in the roofing industry.