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Originally published in Interiors & Sources

01/24/2014

Extend Service Life for a Sustainable Roof

The greenest roof is improving the one you already have

By

 
  • Man working on roof

    Man working on roof

    /Portals/1/images/Magazines/2014/0214/B_0214_Environment_Impacts2.jpg

    Preventive maintenance will greatly extend your roof’s service life and thermal performance. Avoid temporary patches and focus on repairs that address vulnerabilities and defects. It’s also vital to keep accurate records of any roof work so you can prove your system has been maintained according to the manufacturer’s guidelines.

    Man working on roof
  • Roof maintenance

    Roof maintenance

    /Portals/1/images/Magazines/2014/0214/B_0214_Environment_Impacts1.jpg

    Preventive maintenance will greatly extend your roof’s service life and thermal performance. Avoid temporary patches and focus on repairs that address vulnerabilities and defects. It’s also vital to keep accurate records of any roof work so you can prove your system has been maintained according to the manufacturer’s guidelines.

    Roof maintenance
  • Preventive maintenance extends the life of your roof

    Preventive maintenance extends the life of your roof

    /Portals/1/images/Magazines/2014/0214/B_0214_Environment_Impacts3.jpg

    Preventive maintenance will greatly extend your roof’s service life and thermal performance. Avoid temporary patches and focus on repairs that address vulnerabilities and defects. It’s also vital to keep accurate records of any roof work so you can prove your system has been maintained according to the manufacturer’s guidelines.

    Preventive maintenance extends the life of your roof
  • Inspecting roof

    Inspecting roof

    /Portals/1/images/Magazines/2014/0214/B_0214_Environment_Impacts7.jpg

    Routine inspections are key to detecting potential flaws before they come failures. Keep an eye out for blistering, delamination, ponding water, displaced ballast, corrosion, and raised fasteners.

    Inspecting roof
  • /Portals/1/images/Magazines/2014/0214/B_0214_Environment_Impacts5.jpg

  • /Portals/1/images/Magazines/2014/0214/B_0214_Environment_Impacts8.jpg

  • /Portals/1/images/Magazines/2014/0214/B_0214_Environment_Impacts6.jpg

As repairs are called to your attention, it’s critical to address them in an appropriate time frame. Sitting idly on an active repair or corrective measure only leads to deferred maintenance and more costly problems down the road. Any leaks or defects allowing water into the building should be addressed immediately, stresses Michelsen. If you find a vulnerability that has the potential to fail or cause a leak before the next inspection, take care of it within six months to a year. Flaws that aren’t leaking but are too difficult or expensive to fix, such as ponding water or slope issues, should be reserved for when you reroof.

Repairs should also take precedence over patches, which are only temporary measures that don’t address the root issue. Duct tape, for example, can help stop an immediate leak in a membrane tear, but it certainly won’t keep water at bay permanently.

“Repairs, however, remove wet and damaged materials and ultimately restore the roof to its original condition,” Michelsen says. “Depending on the type of defect, you may make a corrective repair to prevent a vulnerability from reoccurring or improve a defect to prevent a future failure.”

These proactive approaches can include adding water barriers under expansion joints or two-part counterflashing. If drainage is an issue, modifications may be necessary for piping. Equipment supports should also provide enough space for repairs and inspections, notes Michel-sen. A proper flashing job, for example, should have penetrations that are spaced apart by at least 12 inches.

Also be conscious of your warranty, which may limit who is allowed to perform repair work. It can also restrict what revisions are permitted on the system in the first place. Even if your proposed repair qualifies under the warranty, make sure you are able to provide proof of maintenance to maintain your coverage.

Conduct Leak Testing
The source of leaks is one of the most difficult issues to track down. Moisture intrusion can occur on an ongoing basis without any visual clues until a major failure occurs, such as the classic case of water pouring on an employee’s desk.

The pathway of the leak can also be challenging to establish without tearing into the roof itself. And as moisture seeps into the building, it comes in contact with wood, steel, and other materials, resulting in damage that can compromise structural integrity.

“Ponding water can also pose a real problem, as sunlight hitting the standing water can degrade the membrane,” explains Kirby. “Getting moisture off your roof is fundamental to the longevity of your membrane.”

Leak Testing Methods

On your own, leaks can be difficult to fully explore. You may see ponding water or have a drip on an employee’s desk, but tracking down the path of moisture intrusion through the assembly requires expert help. A contractor or consultant may use the following methods to test for leaks.

Destructive – Takes apart portions of the roof system to see how it is constructed and what its current condition is. Like removing drywall to find a leak or mold, it is sometimes necessary to physically confirm moisture intrusion through sight and touch. This is typically reserved for small areas of the roof or cores and is one of the more expensive analysis options.

Non-Destructive – Looks at water signatures using indirect methods, including thermal imaging, radio frequency/dielectric, electrical potential/resistance, and nuclear/radioactive. These options provide a visible or audible indication of suspect areas and some can cover large sections of the roof. While the nature of this testing generally avoids damage to the roof, it also limits how far into the assembly problems can be detected.

Direct (Water Testing) – Replicates leak conditions by spraying water on suspect areas, which provides direct feedback about leak sources. Watching water interact with drains, flashing, and expansion joints can provide valuable clues. Infiltrating water, however, can cause disruptions and further damage.

Matt McElvogue and Russ Raymond, Roof Moisture Surveys and Leak Investigation

In addition to regular roof assessments, leak inspections are a valuable way to address this vulnerability. These inspections should be done whenever water infiltration has occurred or soft areas in the membrane appear, says Matt McElvogue, P.E., associate principal for Building Exterior Solutions (BES), a building envelope consulting firm. The goal is to determine the source of the water infiltration, how much propagation has occurred through the roof system, and whether penetration has reached into the deck or compromised any other structural components.

“Even if there isn’t any evidence of water issues, a leak inspection should be conducted every five years as a precaution and after any storm damage that may have caused or worsened leaks,” recommends Russ Raymond, associate principal and registered roof consultant with BES.

Roof replacements are also the perfect time to schedule a leak inspection, he adds, particularly as some testing can be done more easily when parts of the assembly are exposed. It’s an opportunity to uncover hidden moisture issues or take the time to address existing ones. Otherwise you could be covering up problems that may shorten the life of your new roof down the road.

Due to the technical nature of leak testing (see sidebar at left), these inspections are typically performed by a contractor, consultant, or even your roof system manufacturer. To support the process, be prepared to provide supporting documentation of the roof’s past and current condition. Records should include repair history, inspection data, tenant complaints, and overall property condition assessments. Particularly with warranties, this evidence will help you prove that the roof has been maintained according to the manufacturer’s guidelines.

“Any leak reports that facility managers collect are also valuable,” McElvogue notes. “We can often correlate those to weather reports and see what kind of conditions occurred when a leak started. Some leaks only occur in certain instances, such as when wind is blowing one direction or if there’s ponding or wind-blown rain.”

If the leak inspection hasn’t been conducted properly or thoroughly, however, you could be pushed into a premature reroof. Unless you have a catastrophic failure, there are many repair options for leaks that will restore the roof’s integrity.

“Our philosophy is to preserve as much of the existing roof as possible. Don’t be pressured into an unnecessary roof replacement when there’s plenty of undamaged assembly that could be reused,” cautions Raymond. “Retrofits such as coatings, liquid flashings, overlays, and one-way venting allow wet or damaged materials to be resurfaced instead of replaced.”

Such was the case for a recent roof renovation of a hospital building in Texas, which had a modified bitumen roof over a concrete deck. During the renovation, it was discovered that moisture coming through the roof deck was causing blistering and delamination. Other parties involved with the project recommended full replacement, but Raymond’s firm found that the roof could be salvaged with a venting system.


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