: ~$489 at BlueStone Supply or ~$422 at Best Materials .

When selecting a layer, consider which technology best fits your project’s hydrological needs: Overview for green roofs - Minnesota Stormwater Manual

: A more cost-effective and lighter alternative to the standard GRS, designed for projects with lower water retention requirements (~0.042 gal/sq. ft.). : ~$380 at BlueStone Supply . Types of Drainage Layers

: A high-retention system specifically designed for green roofs. It features an inverted dimpled core that retains approximately 1.1 gallons of water per 10 square feet.

Several high-performance geocomposite drainage systems are available for purchase from specialized suppliers. J-Drain GRS (Green Roof Drainage System) - GRS Go to product viewer dialog for this item.

: Applications requiring continuous discharge under heavy compressive loads, such as rooftop gardens or permeable paver bases. J-Drain GRS50

: Includes two filter layers (root-resistant and membrane-protective) and is made from 100% recycled filter fabric. Enkadrain 3811R Green Roof Drainage Layer

: A 3D mesh mat designed to enable quick drainage and breathability. The "3811R" model features geotextile fabric on both sides for maximum filtration. : ~$1,026 for a 39" x 100' roll at Eastgate Supply . Best For