When your installations demand more than just a seal—when they need to withstand constant vibration, dynamic movement, and direct exposure to the elements—Everflex PU-240 delivers. It's engineered to keep critical structural bonds and flexible joints intact, preventing the costly failures that ordinary sealants can't handle in challenging environments like marine, vehicular, or heavy-duty construction. You get a tough, flexible bond that lasts.

Why this product exists

Everflex PU-240 was formulated as a high-modulus, high-strength, moisture-curing polyurethane sealant and adhesive. Its purpose is to provide robust, flexible structural bonding for components and joints in dynamic environments. It addresses the need for a durable, sandable, and paintable solution in a convenient cartridge, making it ideal for small-scale maintenance and installation work where structural integrity and flexibility under movement are non-negotiable. Its exceptional mechanical and abrasion resistance means it stands up to traffic and impacts, preventing premature wear.

The numbers that matter

  • Shore A Hardness 35: This high Shore A value indicates a tough, durable compound. It offers superior pick and tear resistance, making Everflex PU-240 suitable for trafficable areas like pavement joints where ordinary sealants would quickly degrade.
  • Movement Capability +/-25%: The ability to accommodate +/-25% movement means a 10mm joint can expand and contract by 2.5mm without fatiguing the sealant. This ensures the integrity of joints and bonds even in structures that experience constant flexing, settlement, or thermal cycling.
  • Elongation at Break 80%: An elongation of 80% (ISO 8339) demonstrates the product's resilience. It can stretch significantly before failing, providing a safety margin against unexpected forces and ensuring the bond remains intact under stress.
  • Cure Rate 4mm per 24 hours: This controlled cure rate allows for sufficient tooling time (30-minute skin time) while ensuring the sealant hardens predictably. It cures from the outside in, requiring atmospheric humidity to fully set.

What it's like to use

Prepare surfaces thoroughly: they must be dry, clean, and free from contaminants. For impervious substrates, use a two-wipe process with Adheseal Xylene Solvent. Slightly roughen non-porous surfaces before pre-treating with Adheseal 50A Surface Prep. For porous substrates like concrete or masonry, prime with Everflex Supaprime Sealant Primer. Always allow primers to flash off as instructed, typically 30 minutes to 2 hours before sealant application.

For sealing, cut the nozzle at a 45º angle and push the bead ahead of the nozzle into the joint, ensuring full contact. For adhesive applications, cut the nozzle to create a triangular bead and apply flat to the surface before compressing components together. Tool off with a moistened spatula within approximately 5 minutes before skinning occurs. Remove masking tape while the sealant is still wet to achieve clean lines. Clean wet spills and tools with Adheseal Xylene Solvent. For skin cleanup, use Adheseal Hand Wipes.

Where this product excels

  • Waterproofing: Use for perimeter sealing of windows, curtain walls, and metal cladding where building movement demands a highly flexible, weatherproof seal. It provides a durable, long-lasting barrier against water ingress.
  • Civil Construction: Apply to pavement joints, car parks, and driveways. Its high Shore A hardness and abrasion resistance create a tough, pick-resistant surface capable of withstanding vehicular and foot traffic without premature wear.
  • Marine & Vehicular Manufacturing: Ideal for re-caulking marine teak decks, seam sealing, and assembly in RVs and other vehicles. It offers waterproof performance, excellent vibration resistance, and can be used below the waterline once fully cured.
  • Structural Bonding: Employ as a flexible structural adhesive for lightweight construction components and display signs. It forms a high-strength, durable bond that accommodates constant movement and vibration, outperforming rigid adhesives in dynamic scenarios.

How it fits in a real system

Everflex PU-240 typically serves as the final sealing or bonding layer in a system designed for high performance and durability. After appropriate surface preparation and priming (e.g., with Everflex Supaprime Sealant Primer for porous substrates or Adheseal 50A Surface Prep for non-porous), it is applied into joints or between components. For sealant joints, it works in conjunction with compatible backer rod to control depth and prevent three-sided adhesion, ensuring optimal performance and movement capability. Its placement as the exposed layer means its UV stability and mechanical resistance are critical for system longevity.

Choose this when

  • When you need a high-strength, flexible bond: Use when components or joints will experience constant movement, vibration, or impact, such as in marine, vehicular, or heavy construction.
  • When durability in trafficable areas is key: Select for pavement joints, car parks, or driveways where high Shore A hardness provides resistance to picking and abrasion.
  • When paintability and sandability are required: Choose this product when you need to finish over the sealant for aesthetic or functional reasons.
  • For marine applications, including below-waterline: Use for re-caulking teak decks, seam sealing, or other marine structural bonding applications where waterproof performance and chemical resistance are critical.

Don't use this when

  • Not for: Totally confined spaces, as the sealant requires atmospheric humidity to cure.
  • Not for: Aquariums or internal swimming pool applications where high chlorine levels might affect performance.
  • Not for: Adhering mirrors; for this, use Adheseal Hi-Flex 50 Low-Modulus Waterproofing Membrane or MS609.
  • Not for: Structural glazing; for structural glazing, refer to N-80 or N-60 glazing silicones.
  • Not for: Direct contact with copper and brass, as it may cause discolouration.
  • Not for: Bituminous, natural rubber, or EPDM surfaces, or in conjunction with materials that leach oils or plasticisers.
  • Not for: All natural stone without a stain testing program; S100 is recommended for marble or granite after testing.

Everflex PU-240 features a low VOC content of 76 gm/lt, meeting the California South Coast Air Quality Management Rule 1168. This ensures compliance with stringent environmental criteria for greener building practices.