Protecting the roof’s most vulnerable points

By Progressive Materials. 

Sealing flashings, seams and penetrations properly is essential for long-term roof performance. 

Even the strongest roofing system is only as reliable as its weakest point. The flashings, seams and penetrations on a roof are natural stress zones where movement, weather and water pressure can quickly lead to leaks if left unprotected. Choosing the right flashing grade silicone helps ensure a watertight barrier that stands up to harsh conditions, giving you confidence that your work will perform for decades. See why Progressive Materials’ FG-400 maintains the highest reputation in the industry so you can make the most out of your projects. 

Understanding Flashing Grade Silicone 

PM’s Flashing Grade Silicone (FG-400 series) is a high-performance, 100% silicone sealant formulated for use around flashings, on seams and on penetrations. Flashing refers to weatherproofing components installed around roof penetrations (like vents or skylights) and joints to prevent water intrusion. These areas are particularly vulnerable to leaks, so they require a sealant that offers superior adhesion, elasticity and weather resistance. 

This is where FG-400 excels. It’s a thick, paste-like silicone compound that is easy to spread and tool. It forms a durable and waterproof barrier once cured. Its formulation is designed to remain flexible over time, which is essential for withstanding the natural expansion and contraction of building materials due to temperature changes and settling. 

FG-400 series is available in one- and two-gallon buckets and sausage tubes. Typical cure rates and more technical data are available here. 

Key properties 

FG-400 is a great coating to use before or after applying silicone to the field of the roof. Once applied, it offers these key properties: 

1. Extreme weather resistance: Flashing grade silicone maintains its performance in a wide temperature range. It also has very minimal degradation under UV exposure, making it ideal for exterior use. 
2. Strong adhesion: FG-400 adheres well to a variety of substrates including metal, concrete, EPDM, TPO, mod-bit and most other roofing materials. 
3. Flexibility: Once cured, it remains flexible and elastic, accommodating movement in seams, screws and flashing areas without cracking or losing adhesion. 
4. Longevity: Unlike many organic-based sealants that can dry out, crack or shrink over time, silicone can remain stable and functional for decades without the need for reapplication. 

Applications of FG-400 

FG-400 is used widely across commercial roofing projects. Common applications include: 

• Sealing around vents, skylights and pitch pockets. 
• Waterproofing seams in metal or flat roofing systems. 
• Repairing or resealing flashing materials or inside pitch pockets. 
• Creating watertight barriers around HVAC units and ducts. 

Why professionals prefer it 

Many contractors and roofing professionals prefer FG-400 Series Flashing Grade Silicone over traditional sealants like asphalt or acrylic because of its superior performance in extreme conditions. Its elasticity, combined with its thick, viscous composition makes it the ultimate utility coating for any roofing job. 

Conclusion 

Flashing grade silicone is a critical material for ensuring watertight, long-lasting protection in vulnerable building joints and roof penetrations. With its excellent adhesion, UV resistance and elasticity, it offers solid performance for both new construction and repair projects. If you’re looking for a sealant that stands up to time and the elements, our FG-400 Series Flashing Grade Silicone is the smart, reliable choice. 

Reach out to your PM Local Regional Manager with any questions.

Original article and images source: Progressive Materials