DFE-3 (WL). CSI 3-Part Specifications.

	BITUMINOUS FLASHINGS
	Specification DFE-3 (WL)

Base Flashing

For load-bearing wood parapet construction less than 24" (610 mm) above the roof membrane

General

This flashing specification is for use on wood surfaced walls or parapets which are less than 24" (610 mm) high above the roof, and where the roof deck is supported by the wall or 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 coping or counterflashing must be lifted or removed, to permit application of the base flashing.

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). Mop the surface of the roofing felts on the cant with hot Type III* or Type IV asphalt. Immediately set the backer felt into the hot asphalt, smoothing the felt to set it firmly into the asphalt. The backer felt may also be adhered to the felts on the cant using MBR Flashing Cement or MBR Utility Cement. The bottom edge of the backer felt should terminate at the bottom edge (base) of the cant. Do not extend the backer felt onto the horizontal surface of the membrane. The backer felt should extend up and over the top of the parapet, and be nailed at 9" (229 mm) centers in both directions, and at all laps. The backer felt should not be adhered to the wall. Laps in the backer felt should be a minimum of 2" (51 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 beyond the top edge of the backer felt, mop the top of the parapet, the surface of the backer felt, 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 and over the top of the parapet. 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 beyond the top edge of the backer felt, coat the top of the parapet, the surface of the backer felt and out onto the roof membrane with a layer of MBR Flashing Cement approximately 1/8" (3 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 and over the top of the parapet. The sheet should be "worked-in" to ensure that it is firmly and uniformly bonded.

In both hot and cold applications, the vertical joints are to be overlapped a minimum of 4" (102 mm) and be well sealed. Laps in the backer felt and the DynaFlex shall be offset a minimum of 6" (152 mm) from each other. 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 Coping: The metal coping should be installed in accordance with the coping manufacturer’s specifications and details, or in accordance with SMACNA procedures. If a metal coping is 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 the metal coping will be delayed.

Surfacing: DynaFlex requires no additional surfacing.

* Consult a JM Technical Services Specialist regarding the use of Type III asphalt in hot climates.

For an identical copy of this specification, ask for RS-4220.