• No Mixing Required: Ready-to-use with no primer necessary.
• Flexible & Durable: Remains flexible after cure, resists cracking and weather wear.
• Superior Adhesion: Bonds exceptionally to a wide variety of substrates including:
  • Untreated OSB/Plywood
  • Concrete
  • CMU block
  • Metal
  • ICF
  • Gypsum sheathing
• Vapor Permeable: Allows substrates to breathe while maintaining air and moisture protection.
• Environmentally Friendly: Low VOC (< 20 g/l), solvent-free, isocyanate-free.
• Long UV Exposure: Can be left exposed to sunlight for up to 9 months.
• Easy Application: High viscosity for clean trowel or gun application.

• Window and door rough openings
• Joints between dissimilar materials
• Seams in sheathing
• Penetrations and transitions in building envelopes

Common Substrates:

• Untreated plywood or OSB
• CMU block
• Concrete
• Metal
• ICF (Insulated Concrete Forms)
• Gypsum sheathing

Tools Required:

• Sausage gun
• Plastic trowel or putty knife (2"–4")
• Optional: beveled siding for positive sill slope
• Mil gauge

Steps:

1. Prepare the Surface: Clean all rough openings and adjacent sheathing of dust, dirt, and debris.
2. Positive Slope: Add beveled siding to sills if required by the window manufacturer.
3. Gap Filler: Fill gaps larger than 1/4" using Blue Barrier™ Gap Filler before flashing.
4. Apply Flashing:
   • Use a serpentine bead pattern on jambs and headers, then trowel to 25 mils thickness.
   • Cover entire rough opening, extending at least 4” onto adjacent sheathing.
   • Repeat around the exterior sheathing perimeter.
5. Cure: Allow ~30 minutes for setup. It may feel tacky, but as long as it doesn’t transfer to your finger, it’s ready.
6. Window Install: Install window per manufacturer instructions. BB LF can be used as a perimeter sealant.
7. Final Seal: Apply BB LF over top and side flanges of window to tie in with the existing membrane. Leave the bottom flange unflashed to allow drainage.

Coverage: Approx. 64 sq. ft. per gallon at 25 mils thickness (actual coverage may vary).