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| At gravel stops, edges, and penetrations, precautions must be taken to prevent bitumen drippage. |
Felt enveloping is a method to achieve bitumen control. To accomplish this, two plies of non-perforated organic asphalt saturated felts, one ply of Koppers Polyester Reinforced Base Flashing or one ply of Orange Label Sisal Kraft are to be used. Use approximately 18-inch (457mm) wide strips (or as wide as required to cover joint between nailer and insulation) and embed in Koppers Flash-On 441 or hot steep asphalt and secure 9 inches (229mm) of that membrane to the wood nailer. Nine inches (229mm) of the membrane should also extend beyond the edge of the roof. After installation of roofing system, fold over the extended portion of the felt envelope onto the completed membrane and embed in Koppers Flash-On 441 or hot steep asphalt prior to installation of gravel stop.
| Extreme care must be taken to avoid damaging the envelope when installing the metalwork. |
| Koppers will not assume responsibility for coal tar drippage. |
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