Adheseal PU15 Polyurethane Adhesive

Adheseal PU15 is a low-modulus polyurethane sealant and adhesive built for highly flexible movement and connection joints, with a particular strength in window perimeter sealing, glazing weatherseals, curtain walls and façade joints. Its soft Shore A 15 cured profile, 0.2 MPa modulus and greater than 600% elongation allow the seal to move with aluminium frames, cladding and surrounding building materials while maintaining a durable weatherproof joint.

PU15 is widely suited to mechanically fixed window and fenestration details where the window system is already structurally retained and the sealant provides the flexible perimeter weatherseal. This makes it a strong fit for apartment, hotel, commercial and multi-storey glazing work where window frames and adjoining substrates are exposed to thermal movement, weather and changing service conditions.

Polyurethane window sealant for glazing perimeters and curtain walls

For glazing contractors, PU15 is best understood as a window perimeter and curtain wall sealant, not a structural glazing adhesive. It is designed to seal around mechanically fixed window frames, curtain wall interfaces and adjacent façade joints while accommodating movement between materials with different thermal expansion characteristics.

PU15 is also suitable for aluminium fabrication, metal cladding, bolted lap joints, precast and tilt-up panel joints, concrete and masonry façades, seam sealing, lightweight component adhesion, display signs and selected marine or vehicle manufacturing applications.

Why choose PU15?

• Low-modulus flexibility: 0.2 MPa modulus at 100% elongation helps reduce stress on moving joint faces.
• High elongation: greater than 600% elongation to break provides excellent stretch before failure.
• Flexible movement joint performance: classified Type F Class 25 LM to ISO 11600 and suited to ±25% joint movement.
• Soft cured profile: Shore A hardness of 15 after 14 days makes PU15 the softer, more flexible option within the PU15, PU25 and PU50 family.
• Weather resistant: suitable for internal and external joints, with good UV, water and weathering resistance.
• Hot and humid environments: resists mould and mildew growth and maintains a waterproof flexible joint.
• Paintable: compatible with suitable acrylic, oil and rubber-based paints after adhesion testing. Rigid paints may crack as the joint moves.

Compatible substrates

PU15 adheres to a broad range of common construction materials including aluminium, stainless steel, galvanised steel, powder-coated metals, masonry, brick, timber, compatible plastics, stone, painted surfaces, rubber, fibreglass, porcelain and compatible waterproof membranes. Preliminary adhesion testing is recommended, particularly on coated metals, plastics and other variable surfaces.

Window, façade and construction joint installation

Surfaces must be structurally sound, stable, dry and free from dust, oil, grease, release agents, curing compounds and surface water. Concrete should cure for at least 28 days before sealing.

For movement joints, aim for a width-to-depth ratio of approximately 2:1. Internal joints require a minimum width and depth of 5 mm, while external joints should be at least 10 mm wide. Maximum joint width is 30 mm and maximum depth is 15 mm. Where joints are deeper than 10 mm, use correctly sized backing rod to control sealant depth and prevent three-sided adhesion.

On demanding non-porous surfaces such as aluminium, anodised aluminium, stainless steel, PVC, galvanised steel and powder coat, lightly abrade where appropriate, clean thoroughly and use Adheseal 50A surface preparation where priming is required. On porous concrete, masonry, render, mortar and brick, use Everflex Supaprime where required.

Important glazing limitation

PU15 is for window perimeter sealing and weathersealing around mechanically fixed glazing systems. It is not suitable for structural glazing. Where the sealant itself is part of the structural glass-bonding system, use an approved structural glazing silicone such as the specified N60 or N80 system instead.

• Do not use for long-term water immersion, aquariums or internal swimming pools with high chlorine exposure.
• Do not use in totally confined spaces where atmospheric humidity cannot reach the sealant.
• Do not use for mirror bonding.
• Do not use on bituminous surfaces, natural rubber, EPDM rubber or materials that may leach oils, plasticisers or solvents.
• Do not use on lead or copper. Stain-test sensitive natural stone before use.
• Do not apply where active moisture vapour transmission may cause bubbling.

PU15 vs PU25 vs PU50

The Adheseal polyurethane sealant family is designed around different levels of firmness and application demand:

• PU15: the low-modulus, Shore A 15 option for highly flexible window perimeter joints, curtain walls, façade weathersealing and other movement-sensitive connections.
• PU25 FC: the medium-modulus, Shore A 25 all-rounder for expansion joints, precast panels, pavement joints, window perimeters and general construction sealing, with potable-water testing and below-waterline capability once cured.
• PU50: the high-modulus, Shore A 45 option for firmer, tougher joints, including anti-pick and high-contact applications.

Browse the full Polyurethane Sealants range for additional construction joint options.