Key Takeaways
- Silicone Sealants: A neutral or acetic cure sealant with permanent elasticity and flexibility. The ideal choice for long-lasting, waterproof seals in wet areas and high-movement joints.
- Polyurethane Sealants: A high-strength, moisture-curing sealant with exceptional adhesion and high-tensile strength for heavy-duty, structural bonding.
- Hybrid Sealants: A versatile sealant that combines the best properties of both silicone and polyurethane chemistry. Expect superior adhesion, flexibility, and UV stability.
With new materials constantly popping up on construction sites, choosing the right sealant is more challenging than ever. It forces every tradie to ask the big question: Silicone vs Polyurethane vs Hybrid Sealants, which one is up to the task?
The wrong choice can lead to failed bonds and costly callbacks, especially when dealing with modern substrates. That’s why the Soudal team has created this clear, side-by-side comparison to help you find a reliable solution and get the job done.
What Are Silicone Sealants?
Silicone sealants are high-performance, one-component sealants known for their permanently elastic and flexible properties.
- Uses: Professional applications include sealing joints in wet, high-flexibility areas like bathrooms, kitchens, roofs, gutters, and windows.
- Products: Soudal Bathroom & Kitchen Silicone Sealant is ideal for moisture-prone interior areas. Soudal Roofing & Gutter Silicone Sealant is engineered specifically for long-term outdoor exposure on metal roofs and flashings.
- Benefits: Excellent moisture resistance, permanently elastic, and high UV stability. Specific formulations include anti-mould and anti-fungal properties for sanitary applications.
- Limitations: The primary limitations of silicone sealants are that they’re generally not paintable and have limited adhesion to certain non-porous materials like stone.
What Are Polyurethane Sealants?
Polyurethane sealants are high-strength, moisture-curing sealants known for their powerful adhesion and durability in construction applications.
- Uses: The pro’s choice for heavy-duty jobs. When it comes to polyurethane sealants, roofing, concrete repairs, and structural bonding are all common professional uses.
- Products: Soudaflex 45FC Pro is a high-modulus, fast-curing option perfect for versatile sealing, structural bonding, and floor joints, featuring reliable bubble-free curing. For high-movement or expansion joints in concrete, Soudaflex 20LM remains the ideal, low-modulus choice.
- Benefits: Excellent adhesion to a wide variety of substrates and highly resistant to UV and weathering. Once cured, they’re paintable and can handle a wide range of temperatures.
- Limitations: Polyurethane sealants have a longer curing time than silicone, and while they are durable, they are not suitable for continuous water immersion. They also have limited adhesion to certain plastic substrates without a primer.
What Are Hybrid Sealants?
Hybrid sealants are advanced polymer-based sealants that combine the best properties of both silicone and polyurethane to deliver superior performance.
- Uses: Ideal for a wide range of professional applications where both flexibility and high adhesion are critical, including structural bonding, sealing joints, and weatherproofing.
- Products: The Multibond Range provides general versatility. Specific high-performance options include T-Rex Power for a super-strong initial grip, T-Rex Crystal for a clear, invisible finish, and T-Rex Turbo for rapid curing when speed is critical.
- Benefits: They offer high adhesion on many substrates, excellent flexibility, and UV stability. Unlike silicone, they are paintable and can even bond to damp or slightly moist surfaces.
- Limitations: Hybrid sealants are typically more expensive than other types, and their curing time can vary depending on the product and environmental conditions. They are also not suitable for continuous water immersion.
Silicone vs Polyurethane vs Hybrid Sealants: A Side-by-Side Comparison
Some tradies think that any old product will do. But the truth is, a construction sealant’s performance is directly tied to its chemistry. This side-by-side comparison of silicone vs polyurethane vs hybrid sealants outlines the key differences to help you select the best sealant for your construction project.
| Feature | Silicone Sealants | Polyurethane Sealants | Hybrid Sealants |
| Flexibility | Superior flexibility, ideal for high-movement and expansion joints. | Flexible, but generally less so than silicones. | Strikes a balance, providing good flexibility with enhanced strength. |
| Adhesion | Adheres well to non-porous surfaces like glass and metal, but may need a primer on porous materials. | Forms strong bonds with a wide array of substrates. | Provides similar or better adhesion than polyurethane, often without primers. |
| Durability | Extremely UV resistant but may have limited mechanical durability. | Excellent resistance to UV, weathering, and chemicals for long-term outdoor use. | Combines high UV and weather resistance with improved mechanical toughness. |
| Paintability | Generally not paintable. Paint will not adhere to cured silicone. | Paintable with most compatible water-based paints. | Can be painted with most compatible water-based paints. |
| Curing Time | Cures quickly by moisture absorption, with skin formation in minutes. | Longer curing time, often 24-48 hours. Soudaflex 45FC Pro is fast-curing. | Cures faster than traditional polyurethanes, allowing for quicker project turnaround, especially T-Rex Turbo. |
When to Use Silicone Sealants
When you’re finishing off a new bathroom or kitchen, the last thing you want is a callback for a leak or mouldy joint. That’s where Soudal silicone sealants are your best tool. Their permanent elasticity allows them to handle a building’s natural movement without cracking, while their inert chemistry creates a robust, waterproof barrier. Specific formulations with anti-fungal properties provide a clean, long-lasting finish in wet areas. For a job that lasts, Soudal Bathroom & Kitchen Silicone Sealant delivers the professional-grade performance you can trust.
When to Use Polyurethane Sealants
Sealing concrete joints on a high-traffic driveway or floor? A polyurethane sealant is the only tool for the job. Its excellent adhesion and high-tensile strength create a powerful, permanent bond to porous materials like concrete, while its resistance to UV and weathering ensures the joint remains protected for years.
For versatile, heavy-duty structural work, Soudaflex 45FC Pro is the professional choice, delivering high-performance adhesion for general construction and structural bonding. For joints requiring high movement accommodation, Soudaflex 20LM delivers the solid, low-modulus performance required to get the job done right.
When to Use Hybrid Sealants
When facing projects with multiple substrates like concrete and aluminium, hybrid sealants are essential. They seamlessly combine the adhesion of polyurethane with the flexibility and UV stability of silicone, offering a paintable, high-performance solution.
For heavy-duty structural bonding where speed is critical, T-Rex Power delivers a powerful initial grab. When aesthetics are paramount, such as in sanitary sealing or glass, choose T-Rex Crystal for its clear, anti-fungal finish. For general all-round versatility, the Multibond Range is a reliable choice.
Why Aussie Tradies Trust Soudal Sealants
At the end of the day, choosing the right construction sealant isn’t a matter of opinion: it’s a matter of chemistry. While silicone is your go-to for flexibility and waterproofing, and polyurethane excels at heavy-duty structural bonds, hybrid sealants are the ideal solution for modern, versatile jobs. They combine the best of both worlds, making them the ultimate all-rounder for a professional finish.
Explore the full range of Soudal sealants for construction and find the ideal solution, every time.
FAQs
What is the best type of sealant?
There is no one-size-fits-all solution. The “best” sealant is one whose chemistry, whether that’s silicone, polyurethane, or hybrid, matches the application and the level of adhesion, flexibility, and durability your project needs.
How do you choose a sealant?
Consider the substrate you’re bonding to, the amount of joint movement, environmental exposure, and if you need the final result to be paintable.
What is silicone sealant used for?
Silicone sealants are often used to create flexible, waterproof seals in wet areas and on non-porous surfaces. They’re the pro choice for kitchens, bathrooms, and glazing, as their permanent elasticity and resistance to mould ensure a long-lasting, watertight finish.