10.1 fl. oz. (300 mL)
20 fl. oz. (591 mL)
4.5 gal (17 L) in a 5 gal pail
52 gal (197 L) in a 55 gal drum

Sikaflex® -1a
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.
  • Submerged conditions, such as canal and reservoir joints.


  • 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.


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.

Chemical Resistance

Good resistance to water, diluted acids, and diluted alkalines. Consult Technical Service for specific data.

How to Use

Surface Preperation

Priming is not usually necessary. Most substrates only require priming if testing indicates a need or where sealant will be subjected to water immersion after cure. Consult Sikaflex Primer Technical Data Sheet or Technical Service for additional information on priming.


Priming is not usually necessary. Substrates only require priming if testing indicates a need or where sealant will be subjected to water immersion after cure. Consult Sikaflex Primer Technical Data Sheet or Technical Service for ad- ditional information on priming. 


Recommended application temperatures: 40°-100°F. For cold weather application, condition units at approxi- mately 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.

Tooling & Finishing

Tool sealant to ensure full contact with joint walls and remove air entrapment. Joint dimension should allow for 1/4 inch minimum and 1/2 inch maximum thickness for sealant. Proper design is 2:1 width to depth ratio, For use in horizontal joints in traffic areas, the absolute minimum depth of the sealant is 1/2 in. and closed cell backer rod is recommended.


Use personal protective equipment (chemical resistant gloves/goggles/clothing). Without direct contact, remove spilled or excess product and placed in suitable sealed container. Dispose of excess product and container in accordance with applicable environmental regulations.

 Over Painting

Allow 1-week cure at standard conditions when using Sikaflex-1a in total water immersion situations and prior to painting. 


  • When overcoating with water, oil and rubber based paints, compatibility and adhesion testing is essential.
  • Sealant should be allowed to cure for 7 days prior to overcoating.
  • Avoid exposure to high levels of chlorine. (Maximum continuous level is 5 ppm of chlorine.)
  • Maximum depth of sealant must not exceed 1/2 in.; minimum depth is 1/4 in.
  • Maximum expansion and contraction should not exceed 25% of average joint width.
  • Do not cure in the presence of curing silicone sealants.
  • Avoid contact with alcohol and other solvent cleaners during cure.
  • Do not apply when moisture-vapor-transmission condition exists from the substrate as this can cause bubbling within the sealant.
  • Use opened cartridges and uni-pac sausages the same day.
  • When applying sealant, avoid air-entrapment.
  • Since system is moisture-cured, permit sufficient exposure to air.
  • White color tends to yellow slightly when exposed to ultraviolet rays.
  • Light colors can yellow if exposed to direct gas fired heating element.
  • The ultimate performance of Sikaflex-1a depends on good joint design and proper application with joint surfaces properly prepared.
  • The depth of sealant in horizontal joints subject to traffic is 1/2 in.
  • Do not tool with detergent or soap solutions.
  • Do not use in contact with bituminous/asphaltic materials.