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Learn about the following companies in The Greenroof & Greenwall Directory: Green Roof Blocks and JDR Enterprises/J-DRain products.

This serene setting affords an elevated view of the property’s water features and landscape and fulfills the client’s vision for this investment. This project was a redesign and retrofit of an existing rooftop garden. The existing green roof had multiple leaks, poor drainage, and improper soil composition for green roof construction. It was clear that the soil and plants needed to be removed to address the severe roof leakage before a resolution could be considered.

The growth media is a custom blend of 80% Buildex Haydite and 20% composted pine bark (by volume). The plants at the perimeter of the roof are evergreen Junipers used to create vertical height to act as both privacy and safety barrier. Some sedums and native grasses provide prostrate coverage in the areas surrounding the flagstone terrace. A cedar divider is used to form a continuous planter box along the parapet for planting colorful annuals.

A drain core/root barrier combination product was chosen from the JDR Enterprises’ J-DRain product line to act as the root barrier and to provide drainage beneath the green roof growth media. An automated drip irrigation line is used to hydrate the vertical plantings and annuals along the parapet walls.

The maintenance plan for this project is segmented into two categories; roofing work and landscaping work. The roofing work consists of routine inspections and required repair to the sealants used in the membrane and sheet metal flashings as well as inspections of the roof drain access chamber for debris interfering with proper water flow. The landscaping work includes: irrigation and the maintenance of the drip irrigation system, fertilizing as per the requirements of individual species, pruning vertical plants, removal of unwanted plant growth, and the planting and removal of annuals.

During the initial consultation with the client much was discussed regarding the original design intent and the shortcomings of the green roof in its current state. The green roof was constructed by a landscaping firm in a manner similar to planter box construction. Little care was taken to protect the roofing membrane resulting in significant damage. The soil composition was rich in organic material that quickly became saturated and remained wet for long periods.

The client complained that the wet soil attracted mosquitoes and smelled awful. She was also unhappy with the drainage design that allowed excess water to flow from the roof and cascade down the stairway, which created a winter season hazard and allowed soil residue to stain the stonework. A roof drain was installed and the threshold at the stairway was raised to become the overflow protection rather than the primary drainage point for the roof. A new layer of 60 mil EPDM was fully adhered over the entire roof area and allowed to extend the full height of the twelve inch tall parapet. Aluminum termination bar was used to mechanically fasten the membrane flashing to the top of the parapet. A second layer of EPDM flashing was installed at the parapet walls to shield the primary membrane flashing from ultra violet exposure that causes premature aging. Pre-finished sheet metal flashing was then installed over the aluminum termination bar forming three distinctive water barriers and achieving multi-layered waterproofing redundancy.

A Green Roof Drain access chamber was used to keep growth media and plant debris out of the roof drain. The entire roof surface was then covered with J-Drain drain core / root barrier, manufactured by JDR Enterprises. Care was taken to properly overlap all edges of the drain core to prevent growth media from migrating below the drain core and damaging the roof membrane. The custom blended growth media was then carefully spread over the roof surface to a uniform depth of four inches. Additional media was mounded to eight inches to form a continuous berm along the perimeter of the roof in which to re-plant the vertical plants.


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