Green Roof Guide

Foam glass is an ideal product for green roof fill. It’s lightweight, moundable, and readily transportable. Landscape architects and designers can take advantage of compacting Glavel to create angles and fill shapes that suit their design needs. The closed cell structure won’t retain moisture, ensuring that a green roof installation will remain lightweight through any conditions. 

Physical Characteristics

Lightweight – 9.8 pounds per cubic foot

Moundable – Pieces allow for mounds up to 6 feet

Malleable shaping – Pieces allow for slopes up to 45°

Self interlocking – Distributes loads evenly

Produced from recycled glass – Categorized as ‘clean fill’


Inert – Prevents rodents, termites, bacteria, and rot

Closed cell – Acts as a drainage layer

Frost heave resistant – Will prevent cycles of freeze and thaw

Non combustible – Will not burn, nor propagate fires

Water resistant – Closed cell structure facilitates runoff

Green Roof Cross-Sections

Using Glavel as the bulk fill of a green roof system creates opportunities for engineers and landscape architects to build a flooring system that satisfies needs for both performance and aesthetic. Glavel foam glass is placed directly atop a vapor barrier / roofing membrane, which sits directly on the roof slab. The Glavel aggregate layer’s thickness and design can be altered based on project needs. Regardless of the shape of the Glavel fill, a membrane is placed atop the compacted Glavel, and the greenroof system can be installed atop the membrane.

Product Technical Specs


Delivery for green roof fill is done directly to job sites in 3 cubic yard bags. With a cinch at the bottom and straps on the top, bags can be maneuvered directly over a site and product can be directly released. Cranes can lift bags one at a time to get bags atop a roof prior to filling.

Glavel Bag Release
Glavel Mirafi 140N


Glavel recommends the use of Mirafi 140N vapor barrier. Mirafi 140N is a nonwoven geotextile composed of polypropylene fibers, which are formed into a stable network such that the fibers retain their relative position. Mirafi 140N is inert to biological degradation and resists naturally encountered chemicals, alkalis, and acids. Mirafi 140N meets AASHTO M288 Class 3 for elongation > 50%.

Information courtesy of Tencate Geosynthetics.

With Glavel as a green roof fill, structures will be under less physical stress, while the floor of the green roof system will remain seated and intact due to the interlocking nature of Glavel aggregate pieces. A green roof system can reinvent the bounds of green roof capability. To learn more about how a green roof system works, schedule time to speak with a Glavel associate.