One part polyurethane, elastomeric sealant/adhesive

Sikaflex-1a is a premium-grade, high-performance, moisture-cured, 1-component, polyurethane-based, non-sag elastomeric sealant. Meets Federal specification TT-S-00230C, Type II, Class A. Meets ASTM C-920, Type S, Grade NS, Class 35, use T, NT, O, M, G, I; Canadian standard CAN/CGSB 19.13-M87.

Where to use

  • Designed for all types of joints where maximum depth of sealant will not exceed 1/2 in
  • Excellent for small joints and fillets, windows, door frames, reglets, flashing common roofing detail applications, and many construction adhesive applications
  • Suitable for vertical and horizontal joints; readily placeable at 40°F
  • Has many applications as an elastic adhesive between materials with dissimilar coefficients of expansion


  • Eliminates time, effort, and equipment for mixing, filling cartridges, preheating or thawing, and cleaning of equipment
  • Fast tack-free and final cure times
  • High elasticity - cures to a tough, durable, flexible consistency with exceptional cut and tear-resistance
  • Stress relaxation
  • Excellent adhesion - bonds to most construction materials without a primer
  • Excellent resistance to aging, weathering
  • Proven in tough climates around the world
  • Odorless, non-staining
  • Jet fuel resistant
  • Certified to the NSF/ANSI Standard 61 for potable water
  • Urethane-based; suggested by EPA for radon reduction
  • Paintable with water-, oil- and rubber-based paints
  • Capable of +/-35% joint movement



Recommended application temperatures: 40°-100°F. For cold weather application, condition units at approximately 70°F; remove prior to using. For best performance, Sikaflex-1a should be gunned into joint when joint slot is at mid-point of its designed expansion and contraction. Place nozzle of gun into bottom of the joint and fill entire joint. Keep the nozzle in the sealant, continue on with a steady flow of sealant preceding the nozzle to avoid air entrapment. Avoid overlapping of sealant to eliminate entrapment of air.


10.1 fl. oz. cartridge seals 12.4 lineal ft. of 1/2 x 1/4 in. joint. 20 fl. oz. uni-pac sausage seals 24 lineal ft. of 1/2 x 1/4 in. joint.