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46. Flashings for Built-Up Roofing. (Roofers' Specification.) When used with built-up roofing base flashings shall be not less than 5 inches high and extend at least 6 inches out on the roof, in accordance with Specification No. 156 of the Federal Specification Board for the Installation of Metal Flashings with Bituminous Built-up Roofings.

   Cap flashings shall be installed by the Sheet-Metal Contractor as specified elsewhere. The Roofing Contractor shall read carefully the sheet-metal specification.

47. Gravel-Stops. Gravel-stops shall be placed at the edges of all built-up roofs covered with slag or gravel. They shall be formed of one piece of copper to provide a ridge the full height of the roofing material at the outer edge. They shall project on the roof at least 4 inches and be nailed on top of the waterproofing fabric, embedded in pitch, and covered with two layers of felt well-mopped with pitch.

48. Flashing Around Steel Struts. Where steel struts, etc., penetrate a flat roof, a copper pan about 2 inches high above the finished roof level shall be formed around the member. It shall have a flange projecting out on top of the roofing felt or waterproofing at least 2 inches. This flange shall be covered with two layers of felt carried out on the roofing not less than 6 inches and well-mopped with pitch. The pan so formed shall be filled with pitch, and the top surface sloped to drain freely.

49. Flag Pole Flashings. (-A.) Flag poles penetrating a flat roof shall have a circular base flashing extending up the pole at least 10 inches, and 1 inch larger in diameter than the pole. A conical hood secured to the pole by a 1-inch brass band set in white lead and bolted, shall lap the base Hashing at least 3 inches. The whole flashing shall be so constructed as to allow for the movement of the pole.

   (-B.) Patented flashing-flanges or similar devices for flashing flag poles shall be used subject to the approval of the architect. They shall be the product of a recognized manufacturer and shall have a flashing of 18-ounce copper. They shall be installed in accordance with the manufacturer's directions.

50. Flashings for Clay and Cement Roof Tile. Flashings shall be laid as specified elsewhere for base, cap, and continuous flashings. All base flashings running with the length of the tile shall extend out on the roof under the tile as far as is possible without puncture by nails, and shall be formed into a trough by turning up the edge at an angle of 90 degrees. So far as is possible flashings shall be laid to avoid sharp bends and angles, and shall not be nailed. They shall be held in place by the weight of the tile. The manufacturer's specifications shall be followed for flashings of special shapes, etc.

   Where vent-pipes occur the tiles broken by the pipes shall be bedded in mortar or secured with nails and covered with the flashing. Flashings shall extend down the roof to the end of the tile, out on the sides to the first lock or trough, and up the roof to and over the wood battens or to the nails securing the tiles.

   Valley flashings shall be formed to fit the type of tile used and shall extend up the sides of the intersecting slopes, or be turned over the supporting wood battens, to form a valley at least 4 inches deep.

   Flashings against the sides of dormers, etc., on sloping roofs shall continue as a trough under the tile and discharge out on top of the tile below or into the gutter.

   Exposed flashings shall extend with the length of the tiles at least 6 inches and shall be formed over them. Those extending crosswise shall terminate in depressions or locks and be held in place by the adjoining tiles.

51. Scuttles. Covers of roof scuttles shall be covered with copper. Sheets shall be laid with flat seams soldered, and shall be carried over the edge to the underside where they shall be secured with nails 1½ inches apart.

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