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Reroofing watershed

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Reroofing watershed

Moisture surveys verify reroof needs, while proper roof maintenance and installation remain critical requirements

By By Jack Klein, Contributing Editor | August 11, 2010
This article first appeared in the 200209 issue of BD+C.

When Disney, the new owner of The New Amsterdam Theater on Times Square in New York City, wanted to know the condition of the theater's roof, a moisture survey was performed. Results of the survey led to the installation of a new roof. Upon its completion, the roofing manufacturer wanted to ensure that subsequent trades, especially the company that installed the rooftop HVAC system, hadn't damaged the integrity of the roof. Therefore, another moisture survey was undertaken before the manufacturer would issue a warranty.

Conducting two moisture surveys in the course of a project is somewhat unusual in the world of reroofing. However, this was hardly a run-of-the-mill roof.

Constructed with skeletal steel framing, which is most commonly seen in skyscrapers, the theater, which opened in 1903, boasted a unique cantilevered balcony that allowed clear views for all seats in the house. Listed on the National Register of Historic Places in 1980, the once-proud theater, the original home of the Ziegfeld Follies, had fallen into disrepair.

An extensive $30 million renovation once again made the theater a jewel in the rebirth of Times Square. Opening in 1997, the stage version of Disney's The Lion King continues to play to sold out audiences today.

Renovation's results rest on roof

The theater is one example of how important a moisture survey can be in determining the need for and success of a reroofing project.

"The key to any renovation project is the roof, and before you do anything to it you have to know what you're working with," says Chip Cipriani, president of Roof Scan Inc., Stillwater, N.Y., the moisture testing facility that performed both surveys on the theater. "You do a moisture survey either to find out where you can repair a roof as opposed to replacement, or to ensure that a new roof has been installed properly."

Moisture surveys can help cut costs on a project in other ways. Roof Scan's 2-million-sq.-ft. moisture survey for J.C. Penney on the largest building in Connecticut — the company's catalog warehouse in Manchester — is an example.

"We already knew that a new roof was needed, but what we were trying to do was to determine if they could save money in tear-off costs," says Cipriani. Since such costs can run from $1 to $1.50 per sq. ft., the retailer was looking at a $2 million minimum price tag for tear-off alone.

Exposing the steel deck during tear-off also made the building vulnerable to rain. If too much of the roofing was torn off before it could be recovered, any accumulation during the process could be costly.

The subsequent moisture survey showed that only about 10% of the existing built-up roofing (BUR) was actually wet and in need of replacement. Those wet areas were carved out and infilled with new insulation up to the level of the original deck. All gravel was then removed from the roof, which was made as smooth as possible before new insulation was attached. Then a new single-ply membrane was applied over the entire roof. Thanks to the survey, J.C. Penney paid only 10% of the cost that it would have incurred if it had removed the old roof entirely.

Aerial scans read via infrared

While airplanes equipped with infrared cameras are sometimes used to survey large areas of roof, this technique — known as aerial scanning — is uncommon. The technique is more commonly used in the agriculture industry to determine if there are dry spots in groves or fields that are not being adequately watered. Most experts who perform roof moisture surveys say there is no substitute for surveying the roof from on top of it. In all cases, core samples must be taken to verify readings.

A thermogram taken with an infrared camera shows bright red, yellow and white areas where roof insulation is wet.

"You have to walk the roof to make sure you get accurate readings," says Steve Patterson, president of Roof Technical Services Inc., Fort Worth, Texas. "The gravel may be piled thicker in one section of a roof than in others and that could read as a hot spot. Or a patched area can show up as either a hot or cold spot. The camera may even indicate that all of the insulation is wet when it is actually dry."

Maintenance foretells problems

Not all contractors are sold on the idea of moisture surveys as a first step in reroofing. "A well-prepared building owner will have an ongoing roof maintenance program, meaning someone gets up on the roof every year to inspect it, and perform any needed maintenance," says Eric Kirberg, president of Kirberg Roofing Inc., St. Louis. "That person usually has a pretty good idea of what kind of shape the roof is in."

Warning signs that indicate a reroof may be needed include frequent repairs and materials starting to fail, blister, buckle or take on water.

The next step is usually a budgetary decision, says Kirberg. Budget concerns often dictate whether the roof will be replaced or nursed along until funds are available for replacement.

Most building codes dictate that there can be no more than two roofs on a building, meaning tear-off is mandatory. If the building has been roofed more than once, the type of reroofing material used is limited only by slope considerations and issues of material compatibility.

"We try to match our recommended solutions to our customers based on certain criteria, including their specific needs, and what their budget and past preferences have been," says Bob Lyons, executive vice president of Millennium Roofing, Indianapolis. "Instead of attempting to get our customers to think our way, we try to respond to their preferences and needs."

Lyons says that in many instances, building owners may want to correct the roof design flaws or make up for economic constraints that existed when the building was built. Sometimes building uses change. In any case, Lyons says it is just as common to install a different system as it is to reroof using the existing system.

Given the comparative parity of materials, reroofing often involves unique design or application considerations, such as those found at St. Pius Catholic Church in Rock Island, Ill.

Church roof has peaks and valleys

Built in 1964, the roof of St. Pius features poured-in-place, folded concrete plates that provide a peak-and-valley appearance with widely varied slopes. In its center, a low-sloped roof section holds an ornamental, 12-ft.-high crown and 14-ft.-wide skylight. From the air, the roof appears as a stylized dove or a snow angel.

To accommodate the unusually shaped roof, A/E Shive-Hattery, Cedar Rapids, Iowa, specified a white thermoplastic roof membrane, in part because its heat-welded seams are unobtrusive and fit with the seamless look desired by the congregation. Because the flexible membrane could easily be cut while on the ground to fit the roof's varied shapes, it was ideal for the project.

The unusually shaped roof of St. Pius Catholic Church in Rock Island, Ill., led the project’s A/E firm to select a white thermoplastic membrane.

In addition, Jeff Clauson, Shive-Hattery's roof consultant and project manager, redesigned how the various roof elements were flashed into the surface to prevent water infiltration. He specified a rolled and rounded metal roof edge using white-coated metal to maintain the roof's original round edge. Polyisocyanurate insulation was added to the previously uninsulated roof.

Ease of use also contributed to the selection of material for the reroofing of the air traffic control tower cab at Fort Lauderdale-Hollywood (Fla.) International Airport, where water was leaking through the roof onto expensive, life-protecting electronics.

"The major challenge was getting the roofing material up to the tower's roof," says Steve Stanley, supervisor for Advanced Roofing Inc.'s foam and coatings division in Fort Lauderdale. "The only access was via the tower elevators through a hatch into the cab area, where the controllers communicate with the airplanes. Because of this we decided to go with a sprayed polyurethane foam."

Using the foam enabled the contractor to leave the equipment on the ground and run the hose up to the roof. The foam was directly applied onto the existing metal panels.

The bottom line in any reroofing project, whether it's BUR, modified-bitumen, single-ply, spray-applied polyurethane foam or metal, is that the installation must be performed correctly. Given the proper materials and application, the replacement roof should last at least as long as the original.

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