When construction joints demand a sealant that moves reliably with the structure, adapts to various conditions, and delivers consistent results, the choice becomes clear. This product handles facade movement, concrete joint sealing, and general perimeter work with an elastic, durable finish, ensuring joints remain sealed and performing as intended for the long term. Contractors get a straightforward, high-performance sealant that integrates smoothly into diverse projects.

Why this product exists

Sikaflex Construction AP is a 1-component, moisture-curing polyurethane sealant designed for the demanding conditions of general construction. It delivers a highly elastic, flexible, and robust seal for movement and connection joints on porous substrates. Formulated for both indoor and outdoor use, this product provides a non-corrosive, weather-resistant solution that can be painted over to match existing finishes.

The numbers that matter

  • Movement capability of ±25% (ISO 9047, ASTM C 719): This rating confirms the sealant's ability to accommodate significant joint movement, expanding and contracting with building elements without stressing the bondline. It provides a reliable margin for thermal expansion, contraction, and structural shifts.
  • Shore A hardness of 24: This indicates a balanced elasticity, firm enough to resist damage and soft enough to remain flexible under movement. Paired with 90% elastic recovery, the sealant consistently returns to its original shape after deflection, maintaining seal integrity.
  • Sag flow of 0 mm (20 mm profile, 50 °C): This critical specification ensures the sealant holds its shape in vertical and overhead joints, even in warmer conditions. It prevents slumping, allowing for clean, professional finishes on facades and soffits up to 30 mm wide.
  • Tear propagation resistance of 5.0 N/mm: A high tear resistance means the cured sealant is tough. It withstands incidental impact and abrasion on site, reducing the risk of premature failure or damage to the joint itself.

What it's like to use

Sikaflex Construction AP arrives ready to use, requiring no mixing, which simplifies application. The tooling time of approximately 160 minutes and skinning time of 180 minutes provide an ample working window for precise joint finishing, even across longer runs. For optimal results, ensure the substrate is clean, dry, sound, and free from contaminants. For critical or high-performance applications, follow the specific priming instructions:

Always insert a closed-cell Adheseal backer rod to control sealant depth and prevent three-sided adhesion, ensuring the sealant can perform to its full movement capability. The cured sealant can be painted over with most conventional facade coating systems, though a compatibility test is recommended.

Where this product excels

  • Civil Construction: Ideal for movement and expansion joints in pavements, decks, and bridges, where its elasticity and weather resistance accommodate significant temperature swings and traffic loads.
  • Masonry and Concrete: Effectively seals connection and movement joints in concrete elements, precast panels, cement-based renders, and brickwork, providing a durable, flexible barrier against weather ingress.
  • General Building: Suits a broad range of indoor and outdoor sealing applications, including window and door perimeter seals, wall-to-floor junctions, and general facade joints where paintability and long-term elasticity are valued.

Choose this when

  • When you require a reliable, flexible sealant with ±25% movement capability for general construction.
  • When working with porous substrates like concrete, mortar, or brick where good adhesion is critical.
  • When the finished joint needs to be painted over to seamlessly blend with the surrounding structure.
  • When sealing vertical or soffit joints up to 30 mm wide, where a non-sag formulation is essential for a clean finish.

Don't use this when

  • Not for: Natural stone, as the product is not formulated for compatibility and may cause staining.
  • Not for: Bituminous substrates, natural rubber, EPDM rubber, or materials that bleed oils, plasticizers, or solvents; these can compromise the sealant's integrity and performance.
  • Not for: Joints in and around swimming pools, or areas subject to permanent water immersion or water pressure. Alternative sealants are required for these conditions.
  • Not for: Joint widths outside the recommended range of 10 mm to 40 mm, as performance may be compromised.

Compliance with ISO 11600 F 25 LM and ASTM C 920 class 25 certifies its performance as a non-sag façade sealant with ±25% movement capability. These standards confirm the product meets specific criteria for joint sealants used in construction, providing assurance of quality and consistent performance under anticipated movement. VOC compliance with SCAQMD Method 304-91 also indicates adherence to air quality regulations.

Understanding the Sikaflex range

Sikaflex Construction AP is specifically formulated as a go-to choice for general construction sealing and movement joints with up to ±25% capability, particularly effective on porous substrates. For applications that demand a broader range of substrate adhesion, higher movement capacity, or very specific performance characteristics beyond general construction, consider alternative Sikaflex products like Sikaflex PRO. Choosing the right product ensures optimal performance for the specific demands of each project.