Specification No. 176
Cold Applied Polyester & Polyester Base Flashing with ONYX Modified Flashing Cement
  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 ONYX Modified Flashing Cement 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 continuous coating of Koppers ONYX Modified Flashing Cement to the flashing substrate at an approximate application rate of 3 gal./100 sq. ft. (11.4L/9.3m2) into which immediately install the first ply of Koppers Cold Applied Polyester Flashing Membrane (color coded blue) extending from the reglet to not less than four inches (102mm) from the base of the cant onto the roof. Care shall be taken to eliminate all wrinkles and fishmouths.
  6. Apply a second continuous coating of Koppers ONYX Modified Flashing Cement at a rate of 1 1/2 gal/100 sq.ft. (5.7L/9.3m2) to the flashing substrate. Brush any loose material from the back of Koppers Polyester base flashing, apply a continuous coating of Koppers ONYX Modified Flashing Cement at a rate of 1 1/2 gal./100 sq. ft. (5.7L/9.3m2) to the back surface and install one ply of the Koppers Polyester Base Flashing extending from the top of the first ply of cold polyester out onto the roof two inches (51mm) past the cold polyester, taking care to rub the material in thoroughly to obtain optimum adhesion.
  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 Koppers ONYX Modified Flashing Cement.
  8. Install an approved anchor bar system approximately 1/2" (13mm) from the top 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 of flashing to wood. Fastener heads should be sealed with an approved material. 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 Koppers ONYX Modified Flashing Cement.
  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.


 Return to Flashing Specification and Details