Post Office Roof Gets Stamp Of Approval

When you think of commercial buildings in midtown Manhattan, green space isn’t the first thing that comes to mind. However, that might be changing. When it came time to replace the roof on the United States Postal Service (USPS) Morgan Mail Processing and Distribution Center on Ninth Avenue in New York, a vegetative roof was at the top of the wish list.

Built in 1933, the building is designated a historical landmark. It’s also as big as a city block and serves as a major mail sorting facility that operates 24 hours a day. When the existing built-up asphalt roof began to fail, the USPS looked at options to reduce energy usage as part of its goal to reduce energy use by 30 percent by 2015. The objective was to incorporate a garden roof without busting the budget and recycle or reuse as much of the material as possible - all without disrupting normal operations at the facility.

Working closely with the USPS, the construction and design teams from Turner Construction, URS Corp., EKLA landscape architects, and Tecta America’s JP Patti Roofing and Magco units installed nearly 2.5 acres of green roof as part of the 109,000-square-foot overall roofing project. The project was completed on time, under budget, and without interrupting the facility’s operation. The result is a complete transformation of the site and the largest green roof in New York City. 
 

Roofing Contractor spoke with Gordon Hastings and Angie Durhman of Tecta America to get their firsthand perspective on the project. Hastings, Chief Estimator for JP Patti Co Inc. A Tecta America Company, Saddle Brook, N.J., has been with the company more than 25 years. Durhman, Green Roof Manager for Tecta America, works with all of Tecta’s operating units on green roof projects. They were involved with the roofing phase of the project from start to finish.

The new roof system consists of Sika Sarnafil 80-mil PVC loose laid membrane installed over 1/4-inch DensDeck board and 3 inches of extruded polystyrene insulation. Approximately 33,600 square feet of the roof surface is covered with river washed gravel applied over a Sika Sarnafil protection sheet. Concrete pavers cover another 12,700 square feet. Some 63,000 square feet was covered with a protection sheet, drainage mat, separation fabric, water retention mat and growth media. Most of the garden roof area had 4 inches of growth media, but some areas received 8 inches of growth media to form berms. A variety of plants were installed, and nine trees were placed in a planter along the center of the roof.

The existing built-up asphalt roof remained in place, according to Hastings. The loose aggregate was removed by Adler Roof-Vac and used to fill a parking lot in New Jersey. An infrared scan detected some wet insulation, and five areas of insulation were replaced with new insulation to match the height of the existing roof.