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Stego® Mastic

Strong, Flexible, and Vapor Resistant

Stego Mastic is a liquid-applied vapor retardant membrane, designed to be used in conjunction with Stego Wrap vapor barriers and retarders to create a quality installation that greatly resists the ingress of moisture and other gases. It can be used for sealing utility, pipe penetrations, and terminating edges when used in conjunction with Stego Tape or StegoTack Tape. Stego Mastic is available in 2-gallon or 5-gallon pails, and in 20-ounce sausage tubes for repairs and small installations. 

Its many features include:

  • Time-saving aid in achieving an ASTM E1643 installation
  • Sausage Tube feature allows for Stego Mastic to be used with a mastic applicator (sausage) gun, for a more precise application
  • Ideal for sealing multiple pipe penetrations in close proximity and small pipe penetrations
  • Water-based, trowel-grade asphaltic emulsion
  • Made in the USA
ADD TO CART 20-Ounce Tube $20.95
ADD TO CART 2-Gallon $89.95
ADD TO CART 5-Gallon $172.87


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Stego Mastic is a water-based, medium-viscosity, polymer-modified anionic asphalt emulsion. It can be used to seal permanent penetrations of Stego Wrap quickly and easily, especially small pipes, between pipe clusters, and terminating edges.

APPLICABLE STANDARDS American Society for Testing & Materials (ASTM):  

    • ASTM D412: Standard Test Method for Vulcanized Rubber and Thermoplastic Elastomers Tension
    • ASTM E154: Standard Test Methods for Water Vapor Retarders used in Contact with Earth under Concrete Slabs, on Walls, or as Ground Cover
    • ASTM E96: Standard Test Methods for Water Vapor Transmission of Materials
    • ASTM D751: Standard Test Methods for Coated Fabrics
    • ASTM C836: Standard Specification for High Solids Content, Cold Liquid-Applied Elastomeric Waterproofing Membrane for use with Separate Wearing Course
    • ASTM E1643: Standard Practice for Installation of Water Vapor Retarders used in Contact with Earth or Granular Fill under Concrete Slabs

Physical Properties:

    • Tensile/Elongation, ASTM D412: 32 psi, 3860%
    • Resistance to Decay, ASTM E154: 10% perm loss
    • Permeance, ASTM E96: 0.17 perms
    • Hydostatic Water Pressure, ASTM D751: 28 psi
    • Adhesion to Concrete & Masonry, ASTM C836: 7 lbf/in2
    • Hardness, ASTM C836: No cracking
    • Low Temp Flexibility, ASTM C836: No cracking

Additional Benefits:

    • Alternative to boots for pipe penetrations in Stego Wrap
    • Quickly seals around penetrations, especially pipe clusters
    • Easy application from sausage tubes with a standard sausage gun and/or from pails by brush, roller, or trowel
    • Available nationwide
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Stego has the accessories you need to complete an ASTM E1643-compliant installation. Stego Tape, Stego Mastic, Stego Crete Claw Tape and StegoTack Tape enable efficient vapor barrier installations, saving time and resources.


Stego Tape

A low permeance tape designed for use...

Stego Mastic

Stego Mastic

A liquid applied vapor retardant membrane...


Stego Crete Claw Tape

A multi-layered tape...



A double-sided adhesive strip used to bond...

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