When construction joints and cracks demand a reliable, flexible seal that cures fast, you need a polyurethane that gets the job done. Adheseal PU25FC delivers the peace of mind that comes with a robust, paintable seal for critical detailing. It's the go-to choice for preventing water ingress and protecting structures where durability and speed are non-negotiable.

Why this product exists

Adheseal PU25FC became the industry standard because it pioneered speed in Australian polyurethane sealants. Before its introduction, polyurethanes cured slowly. The 'FC' in its name signifies 'Fast Curing', delivering a 60-minute skin time that dramatically reduces project delays. This product provides a tough, durable, and flexible seal for construction joints and cracks. It's formulated to accommodate movement up to ±25% of the joint width, ensuring a permanently elastic and dustproof finish in demanding applications. We engineered PU25FC to be a versatile, dependable workhorse for general construction and critical waterproofing details.

The numbers that matter

  • Shore A Hardness 25: This medium modulus ensures flexibility to handle dynamic joint movement without tearing. It provides a softer, more elastic seal compared to harder polyurethanes, making it ideal for joints that require significant give.
  • Movement Capability ±25%: With an elongation at break exceeding 400%, this product can stretch over four times its original length before failing. This high elasticity provides a significant safety margin against crack propagation and joint failure, even under repeated expansion and contraction.
  • Skinning Time 60 minutes: This 'Fast Curing' (FC) formulation provides ample working time for proper tooling, yet achieves tack-free status quickly. This significantly reduces the risk of dirt pick-up and allows for faster follow-on trades, accelerating project timelines.
  • Cure Rate 3mm per day: A reliable cure rate ensures the sealant develops its full strength and flexibility consistently. This protects your work against early mechanical stress and allows for subsequent treatments like painting or immersion.

What it's like to use

Adheseal PU25FC applies easily, tooling smoothly for a neat finish. Always ensure surfaces are clean, dry, and structurally sound. For optimal long-term adhesion, particularly on porous concrete or challenging non-porous substrates like galvanised steel, use the appropriate primer such as Adheseal 50A or Everflex Supaprime. Apply the sealant by pushing it firmly into the joint, ensuring full contact with both joint faces. Tool off within 15 minutes with a moistened spatula for a smooth, professional appearance. Clean fresh spills and tools with Xylene; cured product requires mechanical removal. If you mask edges for a cleaner line, remove the tape while the sealant is still wet.

Where this product excels

  • Crack and joint treatment — detailing and repair: For filling and sealing movement or static joints and cracks in concrete slabs, walls, and civil structures. Its medium modulus and fast cure make it a primary choice for durable repairs, often after priming with a two-part epoxy primer for enhanced adhesion on damp concrete.
  • Roofing — concrete roofs, membrane-covered tiled: Use PU25FC to seal blow holes, imperfections, and act as a bond-breaker and sealant in concrete roofing systems, especially beneath membranes or tiles. It provides a flexible, waterproof seal that supports the integrity of the overall roofing system.
  • Retaining walls, lift pits, civil structures: This product acts as a critical bond-breaker and sealant in below-ground waterproofing systems for retaining walls and lift pits. Often specified as the final seal after the primary membrane, such as Gripset 2P, it protects against water ingress in high-stress, submerged environments.

How it fits in a real system

Adheseal PU25FC is frequently specified as a final sealing element in critical waterproofing systems. For lift pits and retaining walls, it acts as the robust, flexible seal in the final step, applied after the primary membrane like Gripset 2P. In general crack and joint treatment, it's often the first product applied to fill and seal, working in conjunction with companion products like damp concrete primers and specialised epoxy concrete repair fillers to establish a sound substrate before the final sealant application. Its role is to provide durable, flexible closure, integral to the long-term performance of the system.

Choose this when

  • When the job is Crack & joint treatment — detailing and repair and you need a fast-curing, flexible filler and sealant for concrete or masonry.
  • When sealing expansion joints in precast or tilt-up panels where ±25% movement capability is required.
  • For below-ground waterproofing detailing in lift pits and retaining walls, functioning as a robust bond-breaker and final sealant.
  • When you need a paintable polyurethane (with acrylic, oil, or rubber-based paints) that can also inhibit mould and resist harsh chemicals in general construction.

Don't use this when

  • Not for: Internal swimming pool installations or areas with high chlorine exposure. High chlorine can compromise the sealant's integrity.
  • Not for: Totally confined spaces without atmospheric humidity. This product requires moisture to cure.
  • Not for: Structural glazing applications. For these jobs, specify dedicated structural glazing silicones like Adheseal N-80 or N-60.
  • Not for: Direct, prolonged exposure to harsh UV as a finish coat where aesthetics are paramount. While it passes UV testing, prolonged direct exposure can lead to discolouration over time. For superior long-term UV stability, consider Adheseal Hi-Flex 50.
  • Not for: Bituminous, natural rubber, or EPDM surfaces, or in conjunction with compounds that leach oils or plasticisers, as these can cause degradation or adhesion failure.

Adheseal PU25FC is certified to AS/NZS 4020, making it suitable for contact with potable water — a critical requirement for tanks and water storage applications. It has passed ASTM C793 for UV resistance, demonstrating good durability against environmental exposure, and is tested to AS1530.3 with low ignitability indexes, supporting its use in fire-rated assemblies. Its classification as ISO 11600 Type F Class 25 LM confirms its fitness for purpose as a non-sag, low modulus sealant with ±25% movement capacity, meeting international standards for joint sealants in construction. This product also boasts low VOC and meets Green Star environmental criteria.

Choosing your Adheseal Polyurethane

Adheseal offers a range of high-performance polyurethanes, each engineered for specific demands. Adheseal PU25FC sits as the site-stock default, balancing fast cure, medium modulus, and versatility for general construction and detailing. Consider Adheseal PU15 when your primary requirement is greater movement capability (±50%), where a lower modulus sealant is needed to absorb extreme substrate shifts. In contrast, turn to Adheseal PU50 High-Modulus Polyurethane Adhesive when you require a higher modulus, anti-pick sealant for demanding structural applications, or where superior resistance to vandalism and traffic is paramount. PU25FC is your all-rounder, while PU15 and PU50 address the extremes of movement and hardness, respectively.