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Photo courtesy of ISI Building Products

ISI Building Products is excited to announce its new Viper II Platinum under-slab vapor retarder. High-performance vapor retarders are gaining popularity in residential applications to enhance building safety and longevity. Viper II Platinum is the first of its kind to achieve ASTM E 1745 Class A status for blown films under 10 mils. It is the ideal high- performance under-slab vapor retarder for residential construction.

Viper II Platinum is a co-extruded film engineered from seven-layer extrusion technology using a unique virgin resin formulation. This manufacturing process creates an excellent balance of high puncture and tensile strength while maintaining very low water vapor permeance characteristics. Viper II Platinum retains (long-term) high-performance and will not biodegrade or decompose when exposed to various soil types and below-slab conditions.

Performance is important for under-slab vapor retarders to prevent moisture and soil migration through the slab. Membranes must maintain integrity and sustain foot traffic during installation of the concrete. Failure to provide a continuous vapor retarder under-slab can lead to increased relative humidity, condensation, mold, mildew, degradation, costly flooring failures and damage to moisture-sensitive furnishings within a building’s interior.

Viper II Platinum meets or exceeds all Class A requirements of ASTM E 1745 to provide durable, long-lasting protection against moisture and soil gas. Viper II Platinum is available through ISI’s nationwide network of building materials distributors.


As leaders in building materials innovation, ISI Building Products creates cutting-edge insulation, building products and accessories for a variety of industries. The design and ingenuity of these products reflects its mission: to create impactful solutions for building and construction challenges.


ISI Building Products