characteristics

Soil Depth: Approximately 2-½”
Module Size (plastic): 1′ x 2′ x 1-¾”
Saturated Weight: Approximately 15-17 lbs per square foot
Dry Weight: Approximately 12 pounds per square foot*

What it is

The Lite System is typically used on retrofit projects when the roof is engineered with only 15 to 17 pounds per sf for the green roof component. Its soil depth is a full 2 ½ inches, enough to support many low growing succulents and a limited number of accent plants. It is generally not recommended for hot climates.

What it does

It provides a modest level of storm water management, modest energy savings—especially if attentively irrigated during the warm season. It also meets greenspace requirements in many instances, and provides limited biodiversity. Its plants will support pollinators such as butterflies and honeybees, and the plants that grow in the Lite System are diverse enough to support patterned designs.

What plants work

The plants used in the Lite System include a fairly broad range of low growing Sedums—mostly fine- and medium-textured, as well as a few Alliums, for vertical and textural interest.

How it looks

Because the Sedum plants used with this system are fine to medium-textured and relatively low growing, designs can vary from moss-like to medium-textured (similar to a lawn). Foliage colors can vary from green, to yellow, red and blue, and flowers from white, yellow, and pink to reddish. Various low growing (6″-10″ tall) Alliums can be used for accent and they typically have green or bluish foliage and flowers of white, pink or purple.

What it needs

Because the Lite System has only 2 ½ inches of soil, it will dry out regularly during summer. Therefore, we strongly recommend a built-in irrigation system. During typical summertime weather, it should be watered once per week, usually for 25-30 minutes (about 1 inch of water).

Soil fertility should be managed attentively; typically one application of a high quality sulfurcoated fertilizer each spring is adequate. LiveRoof’s Smart Weeding™ method should be followed (where the maintenance person takes a short “weed walk” every two weeks during the growing season—thus preventing a few baby weeds from growing up and having offspring).

How it’s grown

The base succulent plants (typically Sedums) are usually started from cuttings that are blended, applied to the soil surface, and grown to maturity in the nursery setting. Occasionally, particularly if the designer is looking for something unique, it can be started from a combination of Sedum plugs and cuttings. Accent plants, such as Allium, are planted from plugs or divisions as well. When mature, a process that typically takes 8 to 12 weeks depending upon climate, it is delivered to the project site and installed on the roof.

Comparative cost

The Lite System is economical; it utilizes relatively inexpensive plants, is grown quickly and is fast and easy to install.