Green Roof Solutions drainage options for stormwater management and water retention.

Drainage

Green Roof Solutions offers many different drainage layer options, depending on system goals regarding water retention. The most critical role of the drainage layer is to provide adequate flow of water off the roof during and after a rain event. The design of the different drainage layers allows for a portion of the stormwater to be retained above where the water is allowed to flow freely off of the roof. The systems are designed to ensure that stormwater can be used by plants for longer periods of time without oversaturation of the system. This promotes plant growth, avoids anaerobic soil conditions, and keeps retained water from pooling on the roof.

GRS drainage products typically fit into a green roof system above GRS Root Barrier and below GRS filter fabric. Depending on regional precipitation rates and the water retention goals for your specific project, Green Roof Solutions has a full range of products to meet your needs.

Filter Fabric

Beneath the growing media and above the drainage system, the filter fabric keeps the media from clogging up the drainage while allowing water to flow freely. Green Roof Solutions has a 3.5-oz filter fabric, FF35. An important consideration with filter fabric is the flow rate while preventing media runoff. The GRS FF35 has a high flow rate of 150 gallons per minute per square foot. The FF35 is a needle-punched fabric composed of virgin polypropylene staple fibers that are randomly arranged and needle-punched to form a cohesive geotextile. GRS filter fabric is resistant to UV degradation and to biological and chemical environments found in soil.

Drainage Panels

GR32 / GR52

Green Roof Solutions GR32 and GR52 drainage panels come in 24" x 24" interlocking squares made of 100% recycled high-density polypropylene (HDPP). The GRS GR52 panel size is 24" x 24" x 2.125". The GR52 can hold up to 0.352 gallons per square foot, or 1.4 gallons per panel. The weight of the panels dry is 0.855 lb. per square foot, or 3.42 lb. per panel. The weight of the panels with water is 3.79 lb. per square foot, or 14.81 lb. per panel.

The GRS GR32 panel size is 24" x 24" x 1.25". The GR52 can hold up to 0.165 gallons per square foot, or 0.66 gallons per panel. The weight of the panels dry is 0.6 lb. per square foot, or 2.4 lb. per panel. The weight of the panels with water is 1.93 lb. per square foot, or 7.72 lb. per panel.

GRS1.5

The GRS1.5 is a three-dimensional molded plastic sheet measuring 40" x 48" x 1.5". The GRS1.5 panels are easily cut to fit around rooftop penetrations, perimeters, and drains. The GRS1.5 can hold up to 0.078 gallons per square foot, or 1.04 gallons per panel. The weight of the panels dry is 0.26 lb. per square foot, or 3.5 lb. per panel. The weight of the panels with water is 0.91 lb. per square foot, or 12.18 lb. per panel. The flow rate is 23.5 gallons per minute per foot.

Geodrein

Product made in italy

The Green Roof Solutions Geodrein is a high compressive strength molded plastic panel measuring 19.7" x 19.7" x 2.36". The GRS Geodrein has integral, alternating wing joints that snap the panels together during installation. The GRS Geodrein can hold up to 0.142 gallons per square foot, or 0.382 gallons per panel. The weight of the panels dry is 0.82 lb. per square foot, or 2.2 lb. per panel. The weight of the panels with water is 2 lb. per square foot, or 5.4 lb. per panel. These panels are ideal for intensive gardens, and they provide a stable base for built elements in the garden such as paving and built-in place walls.

Drainage Cores

Green Roof Solutions drainage cores are hybrid products that primarily allow for drainage and aid in filtration and water retention, depending on the product.

Extenduct / Extenduct 2

GRS Extenduct is a 40% recycled drainage core in a waffle pattern with a geocomposite fabric bonded to the top side. The design creates an open and continuous flow path even under high loads. The filter fabric top layer prevents clogging from the growing media, and the waffle entanglements sit directly on the root barrier.

GRS Extenduct 2 includes an additional geocomposite fabric bonded to the bottom side that lies against the root barrier for added protection.

Retenduct / Retenduct 2

GRS Retenduct is a multifunctional layer consisting of a 40% recycled drainage core in a waffle pattern with a 100% recycled moisture retention mat upper layer. The design creates an open and continuous flow path even under high loads. The moisture retention top layer helps to retain water above the drainage layer. The waffle entanglements sit directly on the root barrier.

GRS Retenduct 2 includes an additional geocomposite fabric bonded to the bottom side that lies against the root barrier for added protection.

Aggredrain and Drainage Conduit

Aggredrain is a lightweight aggregate drainage layer made of rotary-kiln expanded clay aggregate and/or expanded shale. Aggredrain is most commonly used at a 1" minimum depth over a moisture retention mat, GRS MRM 14 or GRS MRM 30. A filter fabric layer on top should separate the Aggredrain from the growing media.

The Green Roof Solutions drainage conduit is a stainless steel channel for use with the Aggredrain system. The 6" slotted triangle shape is used beneath the Aggredrain layer and allows for water to flow freely. The channel is designed to be laid end to end and terminates either in the ballasted, unplanted roof area or adjacent to the GRS inspection chamber-covered roof drain. The bottom edge lies flat against the roof to prevent rooftop penetration. GRS drainage conduit is made from 80% recycled 16-gauge stainless steel.

All products made in the United States unless otherwise noted