Burlap Uses in Green Roofing

Green Roof Overview

• Green roofs consist of four basic layers, starting with the waterproof membrane that protects the structure from moisture. A layer of drainage material, such as gravel, sits above the membrane. This drainage layer is topped by the growing medium, typically soil. A layer of vegetation, often consisting of native plants, grows in the growing medium. Burlap may fill one of two basic roles within these layers. It can be used as part of the drainage layer, where it filters water as it flows down to the roof. More commonly, it sits atop the growing medium, where it holds the soil in place and helps to prevent wind erosion. When larger plants are used, installed cut slits in the burlap to accommodate the plants as they take root.

Advantages of Burlap

• Burlap serves as a popular material for roof gardens because it is organic and biodegradeable. Made from woven strands of plant fibers, such as jute or hemp, burlap eventually dissolves and becomes part of the soil. In addition, using burlap also serves as a means of recycling, as many green roof applications use old burlap coffee bean sacks or other repurposed burlap.

Green Roof Benefits

• Green roofs offer substantial benefits when it comes to occupant comfort, energy efficiency and the environment. A green roof can cut cooling loads by 25 percent, according to the Green Building Alliance, resulting in lower energy bills. Vegetation also protects the roof membrane from UV exposure, allowing green roofs to last two to three times longer than traditional roofs, according to the GBA. Green roofs also reduce sound transmission, slow stormwater runoff and serve as a habitat for bees, butterflies and other insects.

Other Burlap Garden Ideas

• Some green roof designs incorporate in innovative ways. For example, in 2010, students at the University of Minnesota Duluth built a rooftop garden using burlap sacks filled with straw bales. A group called Shift Space Design developed simple metal tiles that can be combined to create a green roof of any size. These metal tiles use burlap bags to line a perforated metal tile. The burlap lies beneath the soil, where it filters water and prevents soil from falling through or clogging the holes in the bottom of the tile. An additional layer of burlap covers the top of the soil to prevent it from blowing away as the plants take root.