GacoFlex SF42 Silicone Seam Sealant Detailer - 18.9 Ltr

Delivery:

IN STOCK. Next Day Delivery (if ordered before 13:00) 

Key Features:

• Size: 18.9 Ltr 
• Colour: White 
• Material: 100% Silicone Fibre-Reinforced Coating
• Coverage: Approx 107 linear metres per 18.9L tin when applied at 102mm wide and 1.5mm dry film thickness
• Seam & Joint Protection: Ideal for waterproofing roof laps, joints, cracks, fixings and penetrations
  
• Easy Application: Apply using a brush, roller or trowel
• Solvent Free: Yes
• Shelf Life: 2 Years
• Warranty: System warranties available up to 20 years 

Description:

GacoFlex SF4200 Silicone Seam Sealant is a premium, professional-grade, 100% silicone, fibre-reinforced waterproofing sealant specifically developed to provide long-lasting protection for roof joints, seams, laps, cracks, fixings and penetrations. Designed for demanding commercial, industrial, agricultural and residential roofing applications, this high-performance, solvent-free silicone sealant creates a durable, flexible and weather-resistant waterproof barrier that helps prevent water ingress and protects vulnerable areas of the roof from the elements.

Formulated using advanced silicone technology, Gaco SF42 Silicone Seam Sealant offers excellent flexibility, weather resistance and long-term durability, making it particularly suitable for exposed roofing applications. Unlike conventional sealants that can become brittle or deteriorate with prolonged exposure to sunlight and changing weather conditions, its silicone formulation is designed to maintain flexibility and waterproofing performance throughout seasonal temperature fluctuations. Its resistance to UV exposure, rain and standing water makes it a practical solution for protecting roof details in challenging environments.

Specifically designed for use alongside GacoFlex S42 100% Silicone Roof Coating, Gaco SF42 acts as an essential detailing and reinforcement component within a complete silicone roof waterproofing system. Before applying the main roof coating, the sealant is used to waterproof critical areas such as overlapping metal roof sheets, rooflight surrounds, pipe penetrations, screw heads, fasteners, flashing details and roof joints. Treating these vulnerable areas helps create a more continuous waterproofing system, reducing the risk of leaks and improving the overall reliability of the finished roof coating.

One of the key advantages of GacoFlex SF4200 SeamSeal is its built-in fibre reinforcement, which provides additional strength and durability without the need for separate reinforcing mesh or fabric in typical seam applications. This innovative formulation simplifies the waterproofing process, reduces the number of materials required and helps contractors complete detailed roof sealing work more efficiently. Its thick, workable consistency allows it to be applied directly to joints, seams and awkward roof details using a brush, roller or trowel, helping achieve thorough coverage around complex shapes and surfaces.

Suitable for use on a variety of properly prepared and compatible roofing substrates, including metal roofing, aged asphalt, bituminous roofing systems, cement-fibre roofing sheets and selected single-ply membranes, Gaco SF42 is a versatile solution for both preventative roof maintenance and roof refurbishment projects. Whether sealing exposed fixings on a corrugated metal roof, reinforcing joints on a commercial flat roof or waterproofing intricate details around roof penetrations, the sealant provides targeted protection where water ingress is most likely to occur. Substrate compatibility, adhesion testing and any primer requirements should always be confirmed before application.

Gaco SF42 Silicone Seam Sealant is particularly beneficial when refurbishing older roofs where joints, fixings and penetrations have become vulnerable to leaks through years of weather exposure. By sealing these areas before applying Gaco S42 Silicone Roof Coating, contractors can help extend the serviceable life of existing roofing systems, reduce the likelihood of recurring leaks and potentially avoid the disruption and expense associated with a complete roof replacement, provided the existing roof remains structurally sound.

For roofing professionals, maintenance contractors and property owners seeking a reliable silicone roof seam sealant, metal roof joint waterproofing solution or fibre-reinforced roof repair sealant, GacoFlex SF4200 delivers an effective combination of durability, flexibility and ease of application. When used as part of the recommended GacoFlex silicone waterproofing system, it helps create a seamless, weather-resistant roof surface designed to withstand prolonged exposure to the elements.

Available from Roofing Outlet, Gaco SF42 Silicone Seam Sealant is an ideal choice for professional roof waterproofing, metal roof refurbishment, flat roof repairs and long-term roof maintenance projects where dependable sealing performance is essential.

• 100% Silicone Formula – Provides a durable, flexible and weather-resistant waterproof seal.
• Fibre-Reinforced Technology – Built-in reinforcement means separate mesh or fabric is not normally required.
• Excellent Adhesion – Suitable for properly prepared metal, asphalt, cement-fibre and compatible single-ply roofing surfaces.
• Seam & Joint Protection – Ideal for waterproofing roof laps, joints, cracks, fixings and penetrations.
• Solvent-Free Formula – Low-VOC silicone technology with less than 50g/L VOC content.
• High Solids Content – Approximately 94.4% solids by volume for minimal shrinkage.
• Easy Application – Apply using a brush, roller or trowel.
• Compatible with Gaco S42 – Designed as part of the GacoFlex silicone roof waterproofing system.
• Professional Roof Repair Solution – Suitable for commercial, agricultural and industrial roof refurbishment projects.

What Can Gaco SF42 Silicone Seam Sealant Be Used For?

Gaco SF42 is designed for sealing vulnerable roof details where water penetration can occur.

Typical applications include:

• Metal Roof Seams: Waterproofing overlaps, side laps and joints on corrugated and profiled metal roofing sheets
• Flat Roof Joints: Sealing compatible joints and seams before applying a silicone roof coating
• Roof Fixings: Encapsulating exposed screw heads, bolts and washers to help prevent leaks
• Roof Penetrations: Waterproofing around pipes, vents, rooflights, upstands and other roof details
• Asbestos Cement Roofs: Sealing cracks and joints as part of an appropriate asbestos roof encapsulation system without disturbing the substrate
• Bitumen & Asphalt Roofing: Treating compatible aged built-up roofing seams, cracks and localised damaged areas
• Single-Ply Roofing: Detailing compatible EPDM, TPO and PVC roofing membranes following the manufacturer's preparation and adhesion requirements

Downloads & Data Sheets:

Product Data Sheet

Application Specifications