Green Roof Installation

Why limit your landscaping services? Take them to greater heights.

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By Jonathan Nuss
From the April 2024 Issue

 

If you asked me 25 years ago if I thought vegetative roofs on commercial roofs, let alone residential roofs, were going to be a popular — and profitable — part of our business, I would think you were from another planet. Yet in 2023, our net profit for our install/maintenance of green roofs exceeded the industry standard of 10% to 15%.

It was close to 23 years ago when the phone rang… “This is Charlie Miller from Roofscapes (now Roofmeadow Services, Inc. based in Philadelphia, PA). Would you be interested in offering green roof installations? Word around town is David Brothers Landscape Services is into sustainability and the environment.” Miller was correct. David Brothers is an environmental minded company. We were “green” when it was just a crayon color to the average Joe. We have been collecting rainwater for toilets, irrigation, and hand washing for over 30 years.

Green Roof Installation
The Life Expressions Wellness Center in Sugarloaf, PA was the first green roof project by David Brothers Landscape Services. The building was designed by famed ecological architect Sim Van der Ryn.

 

After multiple meetings, training, and a handshake, our first green roof was underway: Life Expressions Wellness Center in Sugarloaf, PA. Designed by the award winning and renowned ecological architect Sim Van der Ryn, based in California, the building was bell shaped to echo the surrounding hills. Due to this unique shape, we had to install stabilizer bars to keep the soil from sliding down the roof. Overall, we planted over 9,000 sedum plugs on the 6,000 square foot roof. We also installed a biodegradable wind blanket to keep plants in place until the roots took hold.

Why would a client in a northeastern PA town want a green roof, you may ask? Green roofs have many benefits: they provide shade to the building, reduce ambient heat, provide a storm water buffer, keep the building cool in the summer and warm in the winter, provide flowers for bees and other insects, and clean the air. The Well Center’s reasoning was… people just like green spaces. It makes them feel better. And with the benefits listed above, the Well Center’s patients were going to feel better a lot quicker!

Green roofs have many benefits: they provide shade to the building, reduce ambient heat, provide a storm water buffer, keep the building cool in the summer and warm in the winter, provide flowers for bees and other insects, and clean the air.

23 Years Later

Over the past 23 years, a lot has changed in regard to environmental awareness. With requirements for new construction, disturbance rules, and storm water regulations, green roofs are more popular than ever. Philadelphia has adopted a stormwater program where if you disturb 5,000 square feet on a commercial site, you need a stormwater plan. As a result, the amount of green roofs multiplied tenfold. Since you receive “credit” for green roofs, you can maximize the building envelope. Philadelphia now has green roofs on universities, fire stations, PECO’s main office, The University of Pennsylvania, the University of Pennsylvania Hospital, and the Friends Center just to name a few.

In the Summer of 2007, David Brothers was fortunate to install the green roof at the Friends Center, a three-story campus building at 1501 Cherry Street in Philadelphia. The green roof is 8,400 square feet and planted with a mix of seven kinds of sedum. Sedum varieties included:  album Murale “Jelly Bean”, rupestre ‘Prima Angelina’, sexangulare (six-sided), spurium ‘Fuldaglut’ (dragons blood), spurium ‘John Creech’, lanceolatum (spearleaf stonecrop), and stenopetalum (wormleaf stonecrop). We also planted Talinum calycinum (fame flower). We sourced all plants from Maryland-based Emery Knoll Farm, the first green roof nursery in North America. It is owned by Ed Snodgrass, a horticulturalist and source of great knowledge.

Green Roof Installation
David Brothers Landscape Services installed the green roof at the Friends Center in Philadelphia, PA.

 

For the Friends Center media, we used a blower truck to place almost 100 cubic yards of soil. That was the easy part. We also needed to coordinate a street closure so a crane could hoist up all the material including river stone, aluminum edging, drainage mats, and the root barrier. On this roof we did not use a wind blanket, but a sprayable tackifier (just like the one in hydro-seed) to hold the soil in place until the plants took hold.

To break it down from the first layer to the top player, elements of a green roof generally include:

Installing green roofs is very rewarding. It’s gratifying knowing you are doing something for the environment while green space is ever-declining and building envelopes are ever-growing.

  • Roof membrane. This is on all roofs and prevents water from leaking and damaging the roof.
  • Root barrier. A solid sheet of rubber that keeps plant roots from penetrating and damaging the roof membrane. Root barriers are high density poly, or rolled-type, like Tyvek®.
  • Drainage layer. It ensures that the roots get air and don’t become oversaturated.
  • Separation blanket. It prevents migration of soil into the underlying drainage layer.
  • Substrate. It supplies water and nutrients to plant roots, ensures gas exchange at the roots and provides anchorage to support plants.
  • The plants. They trap dust, absorb carbon dioxide, release oxygen, and create habitat.

Roofers take care of the waterproof membrane as well as the insulation under it. We work from the waterproof membrane “up.”

All the roofs we’ve installed are extensive, meaning they comprise only 6″ of soil media or less. Intensive green roofs have soil levels that can reach over 24″. Both are constructed in a similar fashion, from roof top up, with the same layers. The greater the depth of green roof, the stronger the building needs to be. Green roofs always require a structural engineer to calculate the saturated soil weight versus the structural support of the building.

Notable Projects

Other notable green roofs we’ve constructed include: three roofs at St. Mary’s Hospital in Langhorne, PA; the Temple University Ambler Arboretum Field House (PECO Green Roof Garden); the Schuylkill Valley Nature Center; the Waverly Heights and Ann’s Choice retirement homes; and the Mercer Museum in Doylestown, PA.

St. Mary’s Hospital. The Saint Mary’s cloister healing-garden green roof and an ICU green roof not only provide peace and inspiration to the hospital patients, but saves the hospital an estimated 6% to 10% on summer electric bills. The green roof also acts like a giant sponge, holding water back and distributing it at a more even flow during 50-100 year storms.

PECO Green Roof Garden. The PECO Green Roof Garden, located atop the Intercollegiate Athletics Field House at the Temple University Ambler Campus, was designed to educate students, developers, the community, and architects and engineers about this alternative to conventional roofs. This roof provides storm water management, pollinators, and oxygen to the community, where a standard roof does not. The project also maximizes research opportunities for Temple faculty and students interested in studying these impacts.

Schuylkill Valley Nature Center. The Nature Center’s green roof was a 2,215 square foot green roof on the environmental education center. This green roof went well with their mission to promote preservation, education, and the improvement of the environment.

Waverly Heights & Ann’s Choice. Waverly Heights and Ann’s Choice green roofs are at retirement centers. Waverly Heights in Gladwyne, PA provides residents a view of butterflies and pollinators on its accessible outdoor roof. Anne’s Choice, located in Warminster, PA, located its green roof on the 3rd floor for patients in the memory care facility. Now there is a place where the outside can be enjoyed on top of a roof with wonderful sedums.

Mercer Museum. The Mercer Museum green roof provides the visitor with wonderful views of the green roof in the foreground and beautiful views across Bucks County in the distance. The green roof also helps the Museum reduce energy and costs with cooling in the Summer and warmth in the Winter.

 

The Realm Of Residences

Green Roof Installation
The green roof at St. Mary’s Hospital.

 

Green Roof Installation
The PECO Green Roof Garden at the Intercollegiate Athletics Field House on Temple University’s Ambler Campus.

Green Roof Installation
The green roof at Waverly Heights
in Gladwyne, PA.

Green Roof Installation
Green roof installation at Mercer Museum.

Green Roof Installation
Mercer Museum’s completed green roof.

While all the projects mentioned above were for commercial, health care, or education clients, last year we installed a residential green roof on a new home backing up to the Brandywine Meadows Preserve in West Chester, PA. The green roof was designed to be a 144 square foot living piece of art. The roof is on the second floor, right outside the master bedroom and the stairs. This green roof not only added to the permeable square footage of the new construction, it also gave the owner an ever changing mosaic of color through the growing season — with a few evergreen sedum thrown in for a hint of green during the Winter months.

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More recently, we have been installing roof top oases and outdoor living spaces in Philadelphia. These patio roofs are atop buildings/condos and while the environmental benefits are less than a traditional green roof, they still provide renters/owners with green space while emphasizing its importance.

Installing green roofs is very rewarding. It’s gratifying knowing you are doing something for the environment while green space is ever-declining and building envelopes are ever-growing. It’s one small way to help replace the living things we are taking away from Nature and the environment.

Green Roof InstallationNuss is the owner of David Brothers Landscape Services, based in Norristown, PA. Before becoming the owner, Nuss was a part of the estimating, sales/design team since 1999. At David Brothers, he was the lead project manager for maintenance of PWD GSI projects, working on the team of Plymouth Friends and Lutheran Church of Chestnut Hill design with design and implementation. He is also responsible for designing native landscape and hardscape projects, supervising crews on restoration projects, installation of meadows, bioswales, and recommending appropriate plant material for the specific plant communities. Nuss holds a B.S. in Ornamental Horticulture and Environment Design from Delaware Valley College.

Do you have a comment? Share your thoughts in the Comments section below, or send an e-mail to the Editor at cmenapace@groupc.com.

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