Elastovent is a Styrene-Butadiene-Styrene (SBS) modified bitumen base sheet for multi-ply low-slope roofing assemblies where venting of the substrate is desired. Venting is accomplished by the granule underside surfacing facilitating airflow between the bottom of membrane and substrate. A heavy duty fiberglass reinforcement provides a strong and dimensionally stable substrate for other roofing membrane plies. The top surface of membrane is sand, allowing for cold adhesive, heat welding or hot mopping an approved Polyglass base or cap sheet.