Foster® Butylar™ NXT Vapor Barrier Jacketing

Butyl rubber adhesive with a 12µ polyester/25µ aluminum/12µ polyester protective laminate facing

• Foster Butylar™ NXT is used to provide a protective moisture and vapor barrier film over cold and cryogenic piping and equipment insulation applications.
• It may be used over thermal insulation including cellular glass, polyurethane, polyisocyanurate, phenolic, polystyrene, rigid fiberglass and others.
• Foster Butylar™ NXT provides a factory-controlled film thickness and fast, labor saving application.
• The membrane compound is elastomeric allowing for expansion and contraction of the insulation system.
• It is self-healing and forms a strong bond at overlaps without the need for torches or heaters.
• Foster Butylar™ NXT does not contain halogenated materials and has very low leachable chlorides by AS™ C 871 testing. < 50ppm.

• Do not apply to damp, frosty or contaminated surfaces.
• Not intended for direct burial applications.
• Membrane should not be left exposed to UV for more than 6 Months.
• Cover with jacketing as specified.
• Membrane is not to be used for banding or mechanical fastening.
• Standard fastening of insulation is required.
• For application by skilled professionals only.

Preparation

• Insulation must be properly secured in place per insulation manufactures instructions.
• Remove any loose insulation, dust or other contaminants.
• Prime dusty insulation with Foster 85-45 Fos-Stik™ Adhesive to improve adhesion of Butylar NXT.
• Ensure insulation is dry and free of frost or condensation.
• Blistering of sheet may occur if wrap is applied over wet insulation.

Application

• Butylar NXT™ is best applied by cigarette wrapping.
• Cut membrane to desired length.
• Ensure length includes a minimum 2” (50 mm) overlap.
• Start by positioning the membrane such that the finished overlap will allow for water to drain over and not into the lap.
• Peel back six to twelve inches of the release liner taking care not to allow any exposed adhesive to touch itself.
• Firmly press exposed edge of sheet in place and continue removing release liner and smoothing sheet to substrate.
• Avoid wrinkling.
• All longitudinal and circumferential seams must be overlapped a minimum of 2” (50 mm).
• Ensure complete contact at the laps and to the substrate using a roller, squeegee or firm pressure throughout.
• Stagger laps of subsequent pieces.
• When Butylar NXT is applied to the insulation in the shop, finish butted up seams in the field using 4” (100 mm) wide Butylar NXT tape strips evenly spaced over the joint and wrapping all the way around the pipe overlapping a minimum of 2”.
• Any fish mouths or wrinkles in the sheet shall be slit to allow for smoothing and wrapped with a 4” (100mm) strip that covers the entire seam with a minimum 2" (50 mm) overlap.
• All penetrations, insulation supports, valves, expansion and contraction joints and other protrusions must be properly flashed to ensure complete seal between the protrusion and the membrane’s polymer film.
• Foster ElastiSeal™ Sealant, 95-88 may be flashed directly over the Butylar NXT facing.
• Consult engineer’s application instructions for recommendation on proper flashing.
• Use 4” (100 mm) wide Butylar NXT to spiral wrap elbows or cut gores using appropriate templates.
• Overlap all seams by 50%. If a mastic is preferred to cover elbows or fittings adjacent to Butylar NXT membrane do so by extending the mastic and reinforcing mesh a minimum of 2” over the Butylar NXT facing.
• Where white, solvent based mastics are desired, such as Foster Monolar Mastic 60-38 or 60-90, tape terminations of sheet membrane with an acrylic PSA tape to cover the exposed cut ends.
• This will prevent bleed through. Mastic and reinforcing mesh should be extended at least 2” past edge of PSA tape onto membrane facing.
• On exterior applications, Butylar NXT must be protected from the sun within a maximum of 6 months exposure.
• It is recommended jacketing be applied as soon as possible to protect the membrane from damage.
• On low temperature applications for best results the membrane should be stored, until used, at or above 21° C.
• Ensure the insulation and membrane are free from frost or condensation.
• Ensure good adhesion of the membrane at the overlap.
• A heat gun and roller may be used to warm the sheet on the overlap for improved adhesion if necessary.
• Caution must be used to avoid damaging the facing on the sheet.
• Repair damaged sheet by cutting out the damaged section and patching it with new membrane over the empty section, overlapping the existing sheet by a minimum of 2” all the way around the repaired area and taking care to ensure water shedding over the laps.

¹ - Applied to 1/4 inch inorganic reinforced cement board. The flame spread may vary at different product thicknesses and/or when applied over other surfaces. Meets Class A Fire Rating for Exterior Applications.

• Store below 38° C out of direct sunlight for extended periods.
• Short term field storage, keep covered or in ventilated container.
• Store rolls vertically for best results.
• If stored horizontally do not allow excessive weight to damage packaging or rolls.
• For cold weather applications store above 15° C for 24 hours before use for best results.