specification D81-24 of the American Society for Testing Materials, and shall be in paste form. If necessary the paste shall be mixed with sufficient pure boiled linseed oil to give it a putty-like consistency free from lumps and skins.

   The locks formed in the sheets shall be buttered plentifully, and the sheets shall then be joined together in the usual way to form locked seams as specified elsewhere. All excess white lead squeezed out of the seam in the process of forming shall be carefully removed from the roof. Upon completion the seams shall have solid, even layers of white lead between the folds of the metal.

22. Crimped Copper. All copper sheets shall be crimped by passing through heavy rolls to form 3/16-inch ridges in the sheets in the direction of the short dimension.

23. Cleats and Fastenings. All sheets over 12 inches wide shall be fastened by cleats 1½ inches wide and about 3 inches long, spaced as specified elsewhere. They shall be secured to the roof by two nails set about ¾ of an inch from the end and shall have the end turned back ½ inch over the nail heads. The free end of the cleat shall be turned over ½ inch to engage the edge of the sheet and shall be locked into the seam. Where seams are soldered cleats shall be tinned. Except as otherwise specified cleats shall be spaced not more than 12 inches apart. 18 x 24-inch sheets shall have two cleats on the long side and two on the short side of each sheet.

   Where copper is laid on concrete or gypsum roof slabs the roofing contractor shall prepare detailed instructions, with drawings, etc., for locating all fastenings for cleats, edge- and eaves-strips, flashings, etc.

24. Fastenings for Copper Roofing. (Mason's Specification.) In all concrete or gypsum roof slabs which are to be covered with copper roofing or flashings set fastenings for cleats, edge- and eaves-strips, etc., as located by the sheet-metal contractor. Fastenings shall consist of (1) 2 x 2-inch nailing strips placed in the roof slab flush with surface; (2) wood grounds placed in the roof slab at eaves, etc.; (3) expansion inserts to receive nails or screws.

   Before the roof slabs are poured this contractor shall obtain from the sheet-metal contractor complete instructions, with drawings, for locating fastenings.

25. Ribbed (Batten) Seam Roofing. All wood ribs shall be set under another contract to the spacing shown on the drawings. The roofing contractor shall see that these are well secured with all nails well set, truly lined and evenly spaced, and shall not proceed until all faults have been corrected.

   In general sheets shall be 96 inches long and shall be laid with cross seams staggered. They shall be fastened by cleats spaced 8 inches apart and secured alternately to the top and side of the ribs. The cleats shall be locked to the sheet and the ribs shall be covered with a flashing cap locked over the cleats and edges of sheets on both sides.

   All cross seams shall be flat-locked, and (1) thoroughly sweated with solder, as specified under “Slopes of Roofs," (2) filled with white lead. They shall be secured by cleats.

26. Battens or Ribs for Copper Roofing (Carpenters' Specification.) Where indicated on the drawings place on the roof sheathing cypress battens or ribs shaped as detailed. The spacing of these ribs is approximately……….inches. The exact spacing shall be determined by the architect, and this contractor shall use a templet or gage-board to insure proper lining and spacing. They shall be firmly nailed with all nail heads set.

27. Standing Seam Roofing. Seams shall be spaced as shown on the drawings. All sheets shall be, in general, full length. They shall be laid with long edges turned up to form standing seams, and shall be secured by

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