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Notice to the Reader:

The roofing assembly / material information published in the RCABC Roofing Practices Manual and offered below does NOT represent a complete set of the manufacturer’s data or specifications. The preparation of a detailed specification is the responsibility of the design authority.

Manufacturer: Johns Manville Corporation
Accepted for RoofStar Guarantee Program
Product Summary
PermaFlash™ is a flexible flashing system specially designed to work with a variety of bituminous roofing systems to ensure the weatherproofing of a wide range of details. It is a liquid applied two part system consisting of a polyester reinforcing scrim and MBR® Flashing Cement for superior bonding and durability.
PermaFlash™ scrim is a stitch bonded polyester scrim that is both sturdy and pliable to accommodate any shape and provide the reinforcing substrate for the MBR® Flashing Cement. It can even be used on drains and vertical surfaces such as pipes and column penetrations. The systems flexibility allows it to accommodate normal roof movement to retain its weatherability.
PermaFlash™ is easily applied in any location. Because the primer dries rapidly, the process moves quickly. Mixing the MBR® Flashing Cement can be done in the original 19 litre (5 gallon) containers. It stays workable under a wide range of temperatures but cures to form a seamless barrier with exceptional strength and flexibility. For those who prefer a method other than mixing, MBR® Flashing Cement Cartridges are also available. These cartridges contain the two component adhesive and require the use of an MBR® Flashing Cement applicator and static mixer. For more information about this product, visit Johns Manville Corporation.
PermaFlash is specifically formulated for use with all bituminous systems, including hybrid systems. It is excellent for use in projects such as:
  • New and re-roof
  • Metal roofing
  • Paver systems
  • Historic preservation and / or restoration
  • Low permeability
  • Wide application temperature range
  • Low cost per penetration
  • Minimal odour release
  • Great tensile strength
  • Enhanced workability
  • Great crack bridging capabilities
Property Test Method Value
Colour Visual Black
Nominal Thickness with Scrim Micrometer 2.0 mm (80 mil.) Minimum
Tensile Strength ASTM D 412 7.6 MPa (1100 psi)
Elongation ASTM D 412 > 40%
Permeability to Water Vapour ASTM E 96 Method E, 38°C (100°F), 2.5 mm (100 mil) sheet .03 Perms
Hardness ASTM D 2240 @ 25°C (77°F) 65 Shore A
Working Time* @ 24°C (75°F) 30 Minutes
Rainproof After* @ 24°C (75°F) 4 Hours
Suitable for Pedestrian Traffic* @ 24°C (75°F) 12 Hours
Suitable for Vehicular Traffic* @ 24°C (75°F) 48 Hours
Overburden May Be Applied After* @ 24°C (75°F) 24 Hours
Crack Bridging After Heat Aging 3 mm (18")
Softening Point, Ring & Ball ASTM D 36 135°C (275°F)
Elastomeric Waterproofing ASTM C 836, ASTM C 957 Exceeds All Criteria
Abrasion Resistance ASTM D 4060, 1000 gr. / 1000 rev. CS-17 Wheel 1.2 mg Loss
VOC   88 grams / litre (0.74 lbs. / gallon)

  • Working and cure times will vary depending on ambient surface and material temperatures.
Click below for the Technical Data Sheet
Technical Data Sheet

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