Valley FlashLeakBarrier ValleyFlash is a unique and highly versatile glass fiber reinforced sheet sandwiched between two layers of superior quality polymer modified bitumen. Due to its remarkable characteristics, ValleyFlash meets the requirements of ASTM D1970 Moisture Vapor Permeability and ASTM D4869 Liquid Water Transmission tests.


LeakBarrier ValleyFlash is designed for use under composition shingles, shake applications, all types of tiles, as well as in metal roofing applications.

Features and Benefits

  • Cost-effective
  • Technologically advanced valley liner
  • Versatile sheet; can be installed in a variety of applications
  • Easier to work than metal
  • Easy to handle
  • Specially formulated SBS gives lasting performance
  • Polymer modified asphalt gives excellent pliability
  • Good durability
  • Lays flat and resists wrinkling for ease of application
  • Excellent dead fold characteristics
  • Self sealing around nails
  • Meets ASTM D226 Type I and II; ASTM D4601
  • Surpasses ASTM D6380 Class S Type IV requirements (applicable sections)
  • Passes ASTM D4869 Liquid Water Transmission test
  • Passes ASTM D1970 Moisture Vapor Permeability test
  • Complies with the requirements of the International Residential Code (IRC) for Valley Lining material


  • Store rolls in a dry location, protected from the elements.
  • Do not store rolls in direct sunlight for prolonged time.
  • Store rolls upright.
  • When storing two pallets high, position a plywood sheet between pallets.

General Precautions

  • Install ValleyFlash in strict compliance with applicable building code.
  • Keep ValleyFlash rolls clean and free from moisture prior to installation.
  • Follow Occupational Safety and Health Administration (OSHA) safety standards; use common sense measures and adequate precautions to prevent accidents.
  • Ensure proper ventilation of the attic.

Surface Preparation

The substrate shall be clean, dry, and free of voids prior to installing ValleyFlash.


  • For ease of application, cut ValleyFlash into manageable lengths prior to use.
  • Follow standard roofing practice when installing ValleyFlash.


Property Typical Value Reference Test
High/Low Temperature Unrolling Pass ASTM D1970
Breaking Strength >44 lbf/in ASTM D146
Elongation >2% ASTM D6163
Tear Strength 35 lbf ASTM D6163
Moisture Content 0 ASTM D146
Pliability Pass ASTM D146
Compound Stability Pass ASTM D6163
Dimensional Stability <0.5% ASTM D6163
Liquid Water Transmission Pass ASTM D4869
Moisture Vapor Permeability <0.1 U.S. Perms ASTM D1970

Product Data

Width 36 in.
Length 33 ft. 4 in.
Thickness 40 mil (nominal)
Gross Coverage 1 Square
Weight 33 lbs. (nominal)


LeakBarrier ValleyFlash is warranted to be free from manufacturer’s defects.

Note: All statements information and data given herein are believed to be accurate and reliable, but are presented without guaranty, warranty or responsibility of any kind, expressed or implied, except as may be indicated otherwise in this literature.

"On-time delivery and technical support were big factors in choosing Tarco products. The competitive pricing is great for [our] bottom line, and the roofers appreciate its light weight."

- Larry Portman, Big D Roofing

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