When a facade demands both unyielding structural integrity and long-term weatherproofing from a single product, the complexity on site can multiply. DOWSIL 795 simplifies this. It delivers high-performance structural glazing and robust weather sealing from a single, architectural-grade silicone, ensuring both safety and a durable envelope.

Why this product exists

Many sealants tackle either structural glazing or weather sealing. This product is engineered for both. It carries high wind loads while maintaining a flexible, watertight envelope. This dual capability streamlines specification and reduces complexity, offering a versatile solution for facades where performance cannot be compromised. It’s an architectural-grade, neutral-cure silicone sealant built for the demands of modern construction.

The numbers that matter

  • Joint Movement Capability: ±50% means a 10mm joint can expand and contract by 5mm in either direction without failure. This is critical for accommodating thermal expansion, seismic shifts, and building settlement over the long term.
  • A Shore A hardness of 35 defines it as a medium-modulus sealant. This balance provides sufficient flexibility for movement while maintaining the body and strength required for structural support in glazed assemblies.
  • Tension Adhesion Strength of 50 psi (0.345 MPa) at 50% extension after 10,000 hours in a QUV weatherometer confirms its long-term structural integrity and weather resistance, even after extreme UV exposure, crucial for facade longevity.
  • With a working time of 20–30 minutes and a tack-free time of 3 hours, site teams have a practical window for application and tooling, ensuring neat lines and proper bead formation without rushing the job.
  • No staining on granite, marble, limestone, brick, and concrete ensures the sealant will not discolour or leach into porous natural stone or masonry, preserving the aesthetic integrity of high-end facades.

What it's like to use

This is a one-part, neutral-cure silicone that extrudes easily across a wide temperature range, making application straightforward. Effective surface preparation is key: clean all joints, removing contaminants like grease, oil, dust, and old sealants. Masking tape helps achieve neat lines, removed immediately after tooling. While generally not requiring primer on non-porous surfaces, a test placement is always recommended, especially on porous substrates, to confirm optimal adhesion. The sealant cures to a medium modulus silicone rubber upon exposure to atmospheric moisture, requiring 7–14 days for full cure and 14–21 days for full adhesion.

Where this product excels

  • Structural glazing for curtain walls and facades: Providing the critical bond between glass and frame in high-rise buildings, where it must withstand significant wind loads and accommodate building movement. This is a primary application for glaziers and facade engineers.
  • Weather sealing of panel systems: Ideal for architectural cladding, metal panels, EIFS, and precast concrete, where its ±50% movement capability and broad adhesion ensure durable, weather-tight joints against the elements.
  • Expansion joints in masonry and concrete: Its flexibility and robust adhesion are well-suited for accommodating movement in critical expansion joints within commercial concrete and brick structures, preventing cracks and water ingress.

Choose this when

  • When structural glazing is a primary requirement for glass or panel systems, demanding high strength and load-bearing capacity.
  • The facade or assembly requires a sealant capable of both structural bonding and robust weatherproofing from a single product.
  • High joint movement capability (±50%) is essential to accommodate building dynamics, thermal cycling, and seismic activity.
  • Adhesion is required across a broad range of construction materials, including glass, aluminium, steel, painted metal, stone, concrete, and plastics.
  • Long-term weatherability, UV resistance, and temperature stability are critical for the exterior envelope's performance and appearance.

Don't use this when

  • Not for: Applications where the sealant needs to be painted, as silicone sealants typically do not accept paint.
  • Not for: Continuous immersion in water or below-grade applications.
  • Not for: Installation on surfaces exceeding 50°C (122°F) during application.
  • Not for: Totally confined joints, as it requires atmospheric moisture for proper curing.
  • Not for: General weather sealing as the sole requirement; consider Dowsil 791 Silicone Sealant for that specific application.

This product meets rigorous industry standards, including ASTM C 920 Type S, Grade NS, Class 50, Use NT, G, A, and O, confirming its suitability for non-sagging, general construction sealant applications with high movement. It also conforms to ASTM C 1184 for structural silicone sealants, providing confidence in its performance for critical structural glazing requirements.