SOPRA 4897 is an SBS-modified bitumen venting base sheet for use in approved multi-ply membrane and flashing assemblies. SOPRA 4897 is composed of a proprietary formulation of elastomeric styrene-butadiene-styrene (SBS) polymer modified bitumen and is reinforced with a high-quality random glass fiber mat. The topside is surfaced with fine mineral aggregate, while the underside is surfaced with mineral granules to facilitate venting characteristics.
