Bituminous Flashings - Page 5

	BITUMINOUS FLASHINGS

8.8.7 The mixed adhesive has a pot life that is dependent on its temperature. The mechanic will have to use the material in approximately:

8.8.8 The mixing of individual pails of adhesive should be timed so that one can of freshly mixed adhesive is ready for the application crew. Mixed adhesive must not be stockpiled, since the material may cure to an unworkable viscosity before the application crew can use it. In cold weather, the material must be stored and mixed at room temperature.

Important: The MBR Cement Activator must be stored indoors in an area maintained above 60°F (16°C) or crystallization will occur. Refer to the package label on how to correct this situation, if it occurs.

8.8.9 Application: Mixed material is spread on the substrate to be flashed with a trowel to obtain a full, uniform coverage coating, without voids, to an approximate thickness of 1/16 " (1.6 mm). As the coating process proceeds, the DynaFlex flashing is laid into the bed of cement. Specifications that require nailing shall be fastened immediately in order to prevent slippage. Side laps shall be a minimum of 4" (102 mm), and should be sealed with the same flashing cement.

Note: When flashing to sheet metal, JM Metal Primer is required and shall be applied as prescribed on the primer label, prior to the application of any MBR Cement.

8.8.10 All exposed nail heads must be covered with a layer of MBR Flashing Cement. The side laps of the SBS sheet may be coated with a film of MBR Flashing Cement for added protection. Fiber glass fabric may also be embedded in the cement.

8.8.11 All masonry surfaces shall be primed with JM Concrete Primer. Concrete soiled with oil, grease, or form release agents must be thoroughly cleaned and then coated with JM Concrete Primer.

8.8.12 Clean Up: Mineral spirits should be used to clean tools immediately after completion of work. Tools should also be periodically placed in a pail containing mineral spirits to prevent build up of cement. Impervious gloves must be worn during all applications and clean up procedures.

8.9 One-Part Cold Adhesive Application

8.9.1 The material is ready to use as shipped and is not to be thinned. It can be installed in temperatures between 40°F (4°C) and 100°F (38°C). However, when the temperature is below 50°F (10°C), the adhesive must be stored in a warm area, approximately 70°F (21°C), for 24 hours prior to application. To minimize installation difficulties associated with cold weather applications, use the less viscous winter grade material. Also, completely unroll the modified bitumen sheets and allow them to relax at least 15 minutes prior to installation. Turning light-colored sheets upside down (dark side up) helps accelerate the relaxation process.

8.9.2 For best results, make certain the surface to which the cement will be applied is clean, dry and free of loose material. All masonry surfaces which are to receive MBR Utility Cement must be primed with JM Concrete Primer. The primer must be allowed to dry thoroughly before application of the cement.

8.9.3 For large areas, use a notched trowel. Spread the MBR Utility Cement evenly, about ¹/₈ " (3 mm) thick (no greater than ¼ " [6 mm]), working down firmly to ensure good adhesion to the substrate. JM DynaFlex is then embedded into the cement and brushed or rubbed to make full contact and to ensure adhesion.

8.9.4 Coverage: The average coverage is approximately 8 gallons per 100 sq. ft. (3.3 liters/m²), per ply.

8.9.5 Nail or mechanically fasten the modified bitumen sheet as prescribed in the appropriate flashing specification.

8.9.6 All exposed nail heads must be covered with a layer of MBR Utility Cement. The side laps of the SBS sheet may be coated with a film of MBR Utility Cement for added protection. Fiber glass fabric may also be embedded in the cement.

8.9.7 Tools and equipment can be cleaned with mineral spirits.

8.10 Surfacing

8.10.1 JM recommends that GlasTite Flexible flashing sheet be coated with an approved JM Roof Coating such as TopGard Type A, Type B, or Fibrated Aluminum Roof Coating. Hot bitumen is not an acceptable coating.

8.10.2 It is not necessary to apply any surfacing over DynaFlex flashing. DynaFlex is manufactured with integral ceramic granules that protect the underlying bitumen from the elements.

8.11 Application of APP/PAO Modified Bitumen Flashings ("WFE" Specifications)

8.11.1 JM APP/PAO products are durable, flexible, modified bitumen products that can be utilized for flashing. The sheets incorporate either composite reinforcements (glass and polyester) or single reinforcements incorporating polyester or glass. These reinforcements offer strength, puncture and tear resistance as well as conformability. APP products that have polyethylene burn off release films can only be heat welded. APP products that utilize a fine mineral as a release agent can be heat welded or applied in JM MBR^® Utility Cement. (See section 8.13 for cold application instructions.) It is not acceptable in install any APP product in hot asphalt. Conventional cut back cements should not be used to adhere any APP product to the surface being flashed. The JM "Classic" (PAO) line of products can be installed using hot bitumen, cold adhesive or heat welding (see section 8.5 for hot bitumen instructions and section 8.13 for cold adhesive installation instructions).