GAF High Solids Silicone Coating (Formally Unisil HS II Silicone Roof Coating)Why Unisil HS Silicone Roof Coating? Unisil II HS Roof Coating provides superior weatherproofing, ultraviolet resistance, and biological resistance over polyurethane foam insulation and other appropriate substrates. Its pure silicone polymers are naturally fire resistant. Benefits of Unisil HS Silicone Roof Coating include: Tight surface finish effectively resists the attachment of algae, mildew, and mold organisms Exhibits a rapid cure when exposed