Specification No. 172
Application Procedures-Koppers Glass Fiber Felt & Polyester Base Flashing in Steep Asphalt
  1. All surfaces should be smooth, dry and free of debris.
  2. Roofing felts are to be terminated at the top of the cant.
  3. Prime all surfaces from the top of cant to reglet with Koppers High-Pen Primer (1/2 gallon to 1 gallon per square (1.9 to 3.8 L/9.3m2) depending on surface porosity). Allow to dry thoroughly.
  4. Apply Koppers Flash-On 441 to seal the top edge of the cant and ply edges. Gaps over one-half (1/2) inch (13mm) should be filled with a suitable joint backing.
  5. Apply a uniform coating of Steep Asphalt to the flashing substrate into which, while hot, firmly embed the first ply of Koppers Glass Fiber Felt eliminating all wrinkles and fishmouths. Extend from the reglet down to ONLY the base of the cant.
  6. Into a second uniform coating of Steep Asphalt, install one ply of Koppers Polyester Base Flashing (black surface). To the installed first ply of Glass Fiber Felt and to the back side of the polyester base flashing (back mop method) apply a uniform coating of Steep Asphalt into which, while hot, set the base flashing in place brushing all surfaces to ensure uniform adhesion. Extend from the top of the first ply out onto the roof four (4) inches (102mm).
  7. All vertical end laps are to be sealed with Koppers Cold Applied Polyester (color coded blue) or Asphalt Glasfab (minimum 4" (102mm) width) embedded between two courses of Flash-On 441.
  8. Once the system has cooled, install an approved anchor bar system approximately 1/2" (13mm) from top of flashing secured approximately 8" (203mm) on center with wall plugs and fastener devices. The method of installing plugs and fasteners is by pre-drilling when fastening to concrete or masonry. Mechanical fasteners are permissible for attachment to wood. Reference Flashing Specifications, Note No. 6.
  9. Seal the top edge of the flashing felts and anchor bar system by stripping in with 4" (102mm) Koppers Cold Applied Polyester (color coded blue) or asphalt Glasfab and Flash-On 441.
  10. Coat the entire surface of flashing with Koppers Aluminum Coating 444 at a rate of approximately 1 gal/100 sq. ft. (3.8L/9.3m2).
  11. Install metal counterflashing.
NOTE: The use of the “back mopping” technique is required for the application of the Polyester Base Flashing

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