DFE-1 (LB). CSI 3-Part Specifications.

	BITUMINOUS FLASHINGS
	Specification DFE-1 (LB)

Base Flashing

For load-bearing masonry parapet construction with nailing facilities

General

This flashing specification is for use on masonry parapets that can accept and retain the required mechanical fasteners, and where the roof deck is supported by the parapet.

Note: All general instructions contained in the current JM Commercial/Industrial Roofing Systems Manual shall be considered part of this specification.

Wall Preparation: Any previously installed metal cap or counterflashing must be lifted or removed, to permit application of the base flashing.

Apply JM Concrete Primer to the masonry wall, to the full height of the proposed base flashing and counterflashing, and allow the primer to dry thoroughly.

Materials

Base Flashing: Approximately 100 lineal feet (30.5 lineal meters) of base flashing (8" [203 mm] high above the roof) can be installed with the following materials. Usage will vary depending on actual flashing height and field conditions.

Application

Base Flashing: The roofing membrane must extend to the top of the cant. The completed base flashing shall extend not less than 8" (203 mm) nor more than 24" (610 mm) above the level of the roof, and shall extend onto the roof membrane a minimum of 4" (102 mm). Cut the DynaFlex into sections that can be easily handled and installed (6' - 8' [1.83 m - 2.44 m] long), and position upside down on the membrane, to allow the product to relax.

Hot Asphalt Application: Starting just above the point on the parapet where the base flashing will terminate, mop the parapet, the surface of the roofing felts on the cant, and out onto the roof membrane with hot Type III* or IV asphalt. Holding the upper corners of the DynaFlex, position its lower horizontal edge on the roof membrane (minimum 4" [102 mm] from base of cant) and lay it into place over the cant strip and up the wall. The sheet should be "worked-in" to ensure that it is firmly and uniformly bonded. The asphalt temperature shall be a minimum of 400�F (204�C) or at the EVT, whichever is higher, when the DynaFlex is set into it. This higher temperature maximizes the bonding of the base flashing. In cool or cold weather, the back of the DynaFlex sheet should also be mopped with the hot asphalt, and shorter lengths of DynaFlex should be used. PermaMop may not be used to install DynaFlex.

Cold Adhesive Application: Starting just above the point on the parapet where the base flashing will terminate, coat the parapet, the surface of the roofing felts on the cant, and out onto the roof membrane with a layer of MBR Flashing Cement approximately 1 /16" (1.6 mm) thick, or a layer of MBR Utility Cement approximately 1/8" (3 mm) thick. Holding the upper corners of the DynaFlex, position its lower horizontal edge on the roof membrane (minimum 4" [102 mm] from base of cant) and lay it into place over the cant strip and up the wall. The sheet should be "worked-in" to ensure that it is firmly and uniformly bonded.

In both hot and cold applications, the vertical joints shall be overlapped a minimum of 4" (102 mm) and well sealed. Mechanically fasten the base flashing on 6" (152 mm) centers along its top edge. Fasteners must have a 1" (25 mm) minimum diameter integral cap, or be driven through 1" (25 mm) minimum diameter rigid metal discs. It is recommended that the vertical laps be covered with a 1/8" (3 mm) thick layer of MBR Flashing Cement, or a 4" (102 mm) wide strip of fiber glass mesh or ply felt embedded in and trowelled over with a layer of MBR Utility Cement.

Metal Counterflashing: Metal counterflashings, when properly installed, are the preferred method of completing this flashing detail. They should be installed in accordance with the metal manufacturer’s specifications and details, or in accordance with SMACNA procedures, and should overlap the base flashing by a minimum of 4" (102 mm). MBR Cement Counterflashing: If metal counterflashings are not used, the base flashing must be finished with a 4" (102 mm) wide, 1/8" (3 mm) thick layer of MBR Flashing Cement or a 4" (102 mm) wide strip of fiber glass mesh or ply felt, embedded in and trowelled over with a 1 �8" (3 mm) thick layer of MBR Utility Cement, bringing the cement to a feather edge. This procedure should also be used if the application of metal counterflashings will be delayed.

Surfacing: DynaFlex requires no additional surfacing.

For an identical copy of this specification, ask for RS-4217.