The rooftop terrace that crowns the 10-story Mayo 420 building in Tulsa, Okla., is a popular spot for building residents who come up to relax and enjoy the views of downtown from high above Bartlett Square.

The view immediately underfoot is also a pleasant one, thanks to the self-adhering mod bit system that covers the roof. Attention to detail — such as selecting an attractive roof material, retaining the design integrity of the structure and preserving historic architectural elements — has made the Mayo 420 a downtown jewel. However, until recently, it was anything but.

Built in 1910, during Tulsa’s original oil boom, the Mayo Building was a proud landmark in the downtown that grew up around it. By 1994, however, the years had taken their toll and the last office tenant had moved out. Over the next 14 years, the building deteriorated severely as it stood nearly vacant. Even so, its historic significance as the oldest office building in Tulsa was recognized and it was listed on the National Register of Historic Places.

In 2008, Wiggin Properties bought the Mayo Building and set about redeveloping it as luxury rental apartments.

Transforming the Mayo Building from a decaying hulk to a showplace took more than two years, cost more than $30 million and required the efforts of a small army of contractors. This massive undertaking came with more than the usual share of challenges — some of which veteran contractor Don Watkins and his firm, Universal Roofing, helped to solve.

Early in the process, Wiggin Properties Vice President Emily Rohleder called in Watkins, who had worked with Wiggin for years. “Don has done the roofs on all of our properties and he does an exceptional job,” Rohleder said. “I thought it was imperative to have him do this one.”

“This project was a total redo. Half the roof was missing, there was extensive water damage and we had to completely replace all of the mechanicals,” she said. “So we needed someone experienced who could make sure the water would drain correctly and who would properly repair damage done to the new roof during the reconstruction process.”

Work on the roof system was done in phases. Universal Roofing’s first task was to repair the roof structure. Next was installation of the roofing material itself. Watkins specified the Self-Adhering Mod Bit System from Mule-Hide Products Co., Inc. for the job, citing multiple reasons for his choice. “It’s very durable and it looks good,” he said. “It’s very easy to apply, and because it is self-adhering, you don’t need kettles or torches, which makes it much safer.”

Watkins also noted that this product comes in 40-inch rolls, which makes it easier to transport to rooftops than the typical 7-foot or 10-foot rolls. “We had an exterior elevator that we were able to use during the insulation and base sheet installation,” he said. “But by the time the cap sheet was installed, the exterior elevator had been removed and we had to take all of our materials up in the internal elevators, so it really helped to have smaller rolls.”

Universal Roofing put down the polyisocyanurate insulation and two layers of self-adhering mod bit base sheet as a temporary roof covering to keep the building watertight during the lengthy renovation process.

Then for the next two-plus years, Watkins and the Universal Roofing crews made regular visits to the jobsite. Their task was to inspect the roof and repair damage to the roof membrane caused by the other tradespeople who accessed the roof regularly for projects that included a complete replacement of the heating, ventilation and air conditioning systems, the addition of an energy recovery system and the construction of the rooftop terrace. All told, Watkins’ crews made 46 check-and-repair trips to the jobsite during the two-and-a-half year project.

“It’s not uncommon to do this for a month or two with new construction,” Watkins said, “but never in 36 years have I been asked to keep a building dry with a temporary roof covering for two-and-a-half years.”

Finally, as the project neared completion, Watkins’ crew primed the base sheet with asphalt primer and then installed the Mule-Hide Self-Adhering Mod Bit Cap Sheet. The white granular surface of the cap sheet hid unsightly patches made to the base sheets during the construction process and created a sparkling-clean surrounding for the observation deck.

In 2010, a full century after it was first completed, the Mayo 420 reopened with a new lease on life and a vibrant new persona. It boasts “luxurious living in the heart of downtown” with distinctive historic details, modern, high-end amenities and that spectacular rooftop terrace. The first floor of the 10-story structure remains home to a popular downtown dining spot, while a new downtown YMCA occupies the lower level and parts of the first and second floors. Floors three to 10 have been turned into one- and two-bedroom apartments with handsome appointments and 10- to 12-foot ceilings.

“We were honored to be part of such a grand project,” Watkins said.

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 Part of Tulsa’s History

The story of the Mayo 420 is similar to that of many old buildings in other downtowns — beginning life as monumental structures with proud and prosperous owners, changing with the times and adapting to new needs, but ultimately falling into disrepair.

Back in 1910 when the Mayo Building was built, locals clucked that the Mayo brothers, Cass and John, had made a big mistake by locating their imposing new furniture store and office building at 5th and South Main St. on the outskirts of Tulsa. “Too far out of town,” they said.

But the Mayo brothers turned out to be savvy entrepreneurs who built in the right place at the right time. The oil boom was just beginning and with it came tremendous growth for Tulsa and the fortunes of Cass and John Mayo. They soon added another structure — a mirror image of the original five-story Mayo Building and later added five floors to both buildings, combining them into a single 10-story structure.

In the hundred years that followed, the Mayo Building was a fixture in the downtown that grew up around it. As the oldest office building in Tulsa, its historic importance was recognized and it was listed on the National Register of Historic Places. However, by 1994 it had fallen into disrepair and was nearly vacant.

With its purchase in 2008 and subsequent renovation by Wiggin Properties, the Mayo Building is beginning its second century much as it began its first – as a jewel in downtown Tulsa.