DuPont FlexWrap NF solves the corner problem that drives contractors crazy — those curved openings and window corners where regular flashing tape won’t cooperate. This 6-inch wide, 75-foot roll features an extendable micro-creped Tyvek top-sheet that stretches to conform around arches and corners without piecing together multiple segments. The 100% butyl adhesive layer grips reliably, while the split-release liner makes positioning easier in Montana wind.
The tape installs at temperatures down to 25°F (-4°C), which matters when Montana’s construction season pushes into late fall. Nine months of UV stability means it’ll survive if siding installation gets delayed through winter.
Cold-Weather Performance and Installation
The 25°F installation temperature rating changes the game for Montana contractors. Most flashing tapes quit adhering below 40°F. FlexWrap NF keeps working when morning temperatures hover near freezing — common during Montana’s shoulder seasons.
The 100% butyl adhesive avoids the compatibility problems that plague asphalt-based tapes. Butyl won’t react with window manufacturers’ sealants, eliminating warranty concerns. It adheres to wood, OSB, plywood, CMU, metals, and gypsum board — covering every substrate contractors encounter.
The stretchable design eliminates mechanical fasteners in flexed corners. No nails or staples needed where the tape stretches around curves. For arch-top and round-top windows, the tape creates seamless protection without cutting and piecing segments together.
Installation stays straightforward even in cold conditions. Clean the surface of frost, cut to length, peel one side of the split liner, and position. Fan out and stretch at window sill corners. Finish with a J-roller for full adhesion.
Air and Water Barrier Performance
The numbers back up the field performance:
| Specification | Value | Test Standard |
|---|---|---|
| Air Leakage | < 0.04 cfm/ft² | ASTM E1677 & E2357 |
| Water Resistance | No leakage at 718 Pa | ASTM E331 |
| Water Vapor Permeability | < 1 perm | ASTM E96 |
| Thermal Exposure | Class A (176°F for 7 days) | AAMA 711 |
The < 1 perm rating makes this a vapor barrier, not just water-resistant. That distinction matters for window sill pans where trapped moisture causes rot. The AAMA 711 Class A rating proves it handles temperature extremes without adhesive failure.
Applications Beyond Windows
While window and door flashing drives most sales, FlexWrap NF seals wall penetrations including dryer vents, hose bibs, and electrical boxes. The stretchable design conforms to irregular shapes that would require multiple pieces of standard tape.
The tape creates continuous pan flashing for window sills and protects door thresholds and jamb corners. It integrates with DuPont Tyvek WRBs as part of a complete weather barrier system.
DuPont positions FlexWrap differently than their StraightFlash product — StraightFlash handles straight jambs and heads, while FlexWrap tackles sills, corners, and curved openings where stretchability matters. Compared to asphalt/bitumen tapes, FlexWrap’s butyl adhesive maintains compatibility with sealants and performs better at temperature extremes.
Home Depot reviews average 4.8 out of 5 stars, with contractors praising performance sealing window corners and penetrations. Each case contains 4 rolls, with 16 cases per pallet for bulk orders.
FAQ
Can FlexWrap NF replace multiple pieces of flashing tape on curved windows? Yes. The stretchable design creates seamless protection on arch-top and round-top windows without cutting and piecing together multiple tape segments.
What makes the butyl adhesive better than asphalt-based alternatives? The 100% butyl formula won’t react with window manufacturers’ sealants, avoiding compatibility issues. Butyl also performs better at temperature extremes compared to asphalt tapes.
How cold is too cold for installation? FlexWrap NF installs down to 25°F (-4°C) on clean, frost-free surfaces. Below that temperature, adhesion becomes unreliable.
Does the tape require primer on any substrates? No. The AAMA 711 Class A rating specifically notes “no primer” required. The tape adheres directly to wood, OSB, plywood, CMU, metals, and gypsum board.
What’s included with each roll? Each 6-inch by 75-foot roll includes the FlexWrap NF tape with split-release liner. The split liner design aids positioning during installation.
How long can the tape stay exposed before covering? Nine months of UV exposure — enough time to weather delays between flashing installation and siding.
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