Specification No. 174
Application Procedures-Koppers Glass Fiber Felt & Modified Bitumen No. 2041M 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 top of roofing felts to flashing termination with Koppers High-Pen Primer 452, (1/2 gallon to 1 gallon per square (1.9 to 3.8L/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 Modified Bitumen membrane No. 2041M. To the installed first ply of Glass Fiber Felt and to the back side of the No. 2041M (back mop method) apply a uniform coating of Steep Asphalt into which, while hot, set the No. 2041M 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. 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.
  8. 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.
  9. Install metal counterflashing.
NOTE 1: It is recommended that all laps and edges of flashing be heat welded with a propane torch or heat gun and buttered with a rounded trowel even when the field is installed with hot asphalt.

NOTE 2: The use of the "back mopping" technique is required for the application of the 2041M.

NOTE 3: The mineral surfaced sheet must be installed vertically such that the selvage edge may be utilized for laps.

 Return to Flashing Specification and Details