EPDM Bonded Sealing Washers: Are They Really a Game Changer for Roofing and Fastening? Let's Dive In.

After 30 years in the industry, I've seen countless innovations come and go, each promising to revolutionize our work. When I first encountered EPDM bonded sealing washers, I was intrigued but also skeptical. Could something as simple as a washer truly make a significant difference? Now, having worked with them extensively and seen their impact firsthand, I can confidently say – yes, they absolutely can.

But what exactly are EPDM bonded sealing washers, and why should you care? Let's break it down, drawing on my experience and the knowledge I've gathered over the years.

What Makes EPDM Bonded Washers Different? It's All About That Seal.

In essence, an EPDM bonded washer is a two-part component: a robust steel washer combined with a gasket made of EPDM rubber. EPDM stands for Ethylene Propylene Diene Monomer, and it's a type of synthetic rubber known for its incredible resilience to weather and wear. Think about it – roofing and outdoor applications are constantly battling the elements. That's where EPDM shines.

Traditional rubber gaskets? They often fall short. They can flatten, deform, and lose their sealing properties over time, especially under pressure and temperature fluctuations. This can lead to leaks, corrosion, and ultimately, structural issues. Nobody wants that, especially not after investing in a project.

EPDM, on the other hand, is in a different league. Let me tell you why, based on years of dealing with sealing challenges:

Unmatched Flexibility and Pressure Resistance: Unlike standard rubber, EPDM is incredibly flexible. It doesn't just squish and flatten under pressure. Instead, it maintains its shape and sealing ability, even under considerable force. This is crucial for maintaining a watertight seal in demanding applications.
Long-Term Shape Retention and Tightness: This is where EPDM truly excels. It resists deformation over time, ensuring a consistent, tight seal for years. Think about the longevity of a roof or any outdoor structure – you need components that can stand the test of time, and EPDM delivers.
Superior Conformity, Even at Angles: Ever tried to install roofing screws at a slight angle? It’s not ideal, but sometimes necessary. Standard washers can struggle to seal properly in these situations. EPDM gaskets, however, conform much better, maintaining a seal even when things aren't perfectly aligned. This gives you more flexibility and reduces the risk of leaks.
UV and Weather Resistance – A Must for Outdoor Use: EPDM is naturally resistant to ultraviolet (UV) radiation and ozone, which are major culprits in the degradation of many materials exposed to the sun and weather. This inherent resistance means EPDM gaskets last longer and maintain their performance in harsh outdoor environments. Sulfur-free composition also means it won't degrade from UV exposure, unlike some cheaper rubber alternatives.
Environmentally Conscious Runoff: In today's world, environmental considerations are paramount. EPDM is a cleaner material. It doesn't leach pollutants into rainwater runoff, which is a significant advantage for sustainable building practices. This is something that's become increasingly important in my projects over the years.
Extreme Temperature Performance: From freezing winters to scorching summers, outdoor applications endure extreme temperature swings. EPDM performs reliably across a wide temperature range, typically from -40°C to +90°C. This minimal temperature deformation ensures consistent sealing, whether it’s the dead of winter or the peak of summer heat. Even if it freezes or overheats, it bounces back, unlike conventional rubber that can become brittle or lose its shape.

The secret to the EPDM bonded washer's effectiveness lies in how the gasket is attached. It's vulcanized – essentially, chemically bonded – to the steel washer. This creates a single, integrated unit where the steel provides strength and the EPDM provides the seal. The steel washer itself often has a slightly concave or annular shape. This clever design helps distribute pressure evenly, ensuring a secure and stable connection without damaging the underlying surface.

Where Do EPDM Bonded Washers Really Shine? Applications in the Real World.

So, we know what they are and why they're good, but where are EPDM bonded washers actually used? Based on my experience, their primary application is in roofing and external cladding. Think about metal roofing, corrugated sheets, and similar materials. These are all prime candidates for EPDM bonded washers.

Specifically, they are a cost-effective and highly reliable solution for:

Roofing Screw Connections: This is arguably their most common application. When you're fastening roofing sheets, you need a watertight seal at every screw point. EPDM bonded washers provide that, preventing leaks and protecting the structure from water damage. I’ve seen firsthand the difference they make in preventing costly roof repairs down the line.
Attachment of Roll and Sheet Materials: Beyond roofing, any application involving the attachment of sheet or roll materials, especially in external environments, can benefit from EPDM washers. This could include cladding, siding, and various industrial enclosures.
General Fastening in Weather-Exposed Areas: Anywhere you need a reliable, weather-resistant seal around a fastener, EPDM bonded washers are a strong contender. From agricultural buildings to industrial sheds, their versatility is undeniable.

Seeing is Believing: Visual Guide to EPDM Bonded Washers

Let's get visual. Here are some images that showcase the construction and different types of EPDM bonded washers.

This image shows a standard EPDM bonded sealing washer. Notice the clear separation between the steel washer and the black EPDM gasket. The steel provides the structural integrity, while the EPDM does the sealing. This particular washer uses 14-10# steel, indicating its material and gauge.

Here's another example, this time using 16-12# steel. You can see the same basic construction – steel washer and EPDM gasket – but with slightly different dimensions. The gauge of steel used will vary depending on the application and the required strength.

And one more, this one made with 16-14# steel. Again, the core design principle remains consistent: a robust steel washer bonded with a durable EPDM gasket. The variations in steel gauge and dimensions allow for customization based on specific project needs.

Conductive vs. Non-Conductive EPDM: Understanding the Options

One important distinction to be aware of is the difference between conductive and non-conductive EPDM gaskets. For most standard roofing and fastening applications, non-conductive EPDM is perfectly adequate. However, in certain situations, particularly with metal roofing systems, conductive EPDM gaskets offer an added advantage.

Conductive EPDM is designed to provide an electrical path between the fastener and the roofing material. This is important in some metal roofing systems to prevent galvanic corrosion. Galvanic corrosion occurs when dissimilar metals are in contact in the presence of an electrolyte (like rainwater), creating a corrosion-inducing electrical current. Conductive EPDM helps equalize the electrical potential, minimizing this risk.

Non-conductive EPDM, on the other hand, acts as an electrical insulator. While it provides excellent sealing and weather resistance, it doesn't offer the electrical conductivity of its conductive counterpart.

The choice between conductive and non-conductive EPDM depends on the specific application and the materials being used. For most general roofing applications, non-conductive EPDM is sufficient. However, if you're working with metal roofing systems and are concerned about galvanic corrosion, conductive EPDM is worth considering.

Let's look at the specifications for both types:

Conductive EPDM Bonded Washer Dimensions

Name	Metal Outer Diameter A±0.2 mm	Metal Inner Diameter B±0.25 mm	EPDM Inner Diameter C mm	Metal Thickness Tm±0.1 mm	EPDM Thickness Tr±0.2 mm
14-10# steel	14	5.4	3.65-4.20	0.8	2.5
16-12# steel	16	6.1	4.30-4.80	0.8	2.5
16-14# steel	16	7	5.10-5.60	0.8	2.5

EPDM Hardness: 75±5 degrees
Gasket Material: Conductive Ethylene Propylene Diene Monomer Rubber EPDM

Non-Conductive EPDM Bonded Sealing Washer Dimensions

Name	Metal Outer Diameter A±0.2 mm	Metal Inner Diameter B±0.25 mm	EPDM Inner Diameter C mm	Metal Thickness Tm±0.1 mm	EPDM Thickness Tr±0.2 mm
14-10# steel	14	5.4	3.65-4.20	0.8	2.5
16-12# steel	16	6.1	4.30-4.80	0.8	2.5
16-14# steel	16	7	5.10-5.60	0.8	2.5

EPDM Hardness: 75±5 degrees

As you can see, the dimensions are identical for both conductive and non-conductive versions. The key difference lies in the electrical properties of the EPDM gasket material itself.

Installation is Key: Getting it Right with EPDM Bonded Washers

Even the best materials are only as good as their installation. With EPDM bonded washers, proper installation is crucial to achieving a reliable, long-lasting seal. Over the years, I've seen projects fail not because of the materials, but because of installation errors. Let's look at some common pitfalls and best practices.

INSUFFICIENT TIGHTENING: The Leak's Best Friend

Under-tightening is a common mistake. If the fastener isn't tightened enough, the EPDM gasket won't compress properly to create a seal. This leaves gaps, allowing water to seep in under the washer and around the fastener. The result? Leaks, corrosion, and potential structural damage. It's a recipe for disaster that's easily avoided with proper torque.

CORRECT INSTALLATION: The Gold Standard

Properly tightened, the EPDM gasket compresses just enough to fill any minor imperfections on the surface and around the fastener. The seal flows inwards, creating a watertight barrier. This is what you want – a tight, reliable seal that protects against leaks and corrosion. "Tight against surface, Seal flows inward to seal minor fastener diameter and surface." This is the key to long-term performance.

EXCESSIVE TORQUE: Too Much of a Good Thing

Over-tightening might seem like it would create a better seal, but it can actually backfire. Excessive torque can cause the washer to deform, a phenomenon sometimes called "reverse dishing." This deformation can compromise the seal and even damage the surrounding material. "Causes reverse dishing. Leakage under the seal is possible." It’s counterintuitive, but over-tightening can be as bad as under-tightening.

The Takeaway? Torque Matters.

The key to successful EPDM bonded washer installation is proper torque. You need to tighten the fasteners enough to compress the gasket and create a seal, but not so much that you damage the washer or the surrounding materials. Always refer to the manufacturer's recommendations for torque specifications. Using a torque wrench is highly recommended, especially for larger projects, to ensure consistent and correct tightening.

Beyond EPDM: Exploring Similar Sealing Solutions

While EPDM bonded washers are a fantastic solution for many applications, it's important to know that they're not the only option out there. The world of sealing technology is constantly evolving, and there are several similar approaches worth considering, depending on your specific needs and project requirements.

Integrated Sealing Fasteners: These are fasteners that have a sealing element built directly into their design. This can include:

O-ring seals: Fasteners with integrated O-rings provide a compression seal, often used in hydraulic and pneumatic systems. While not directly comparable to EPDM washers in roofing, they illustrate the concept of integrated sealing.
Pre-assembled washer fasteners: Some fasteners come pre-assembled with various types of washers, including nylon, neoprene, or other rubber-based washers. These offer convenience and ensure the correct washer is used.
Self-sealing screws: These screws have a thread design that creates a seal as they are tightened. They are often used in metal construction where a quick and easy seal is needed.

Alternative Washer Materials: While EPDM is excellent, other materials are used for sealing washers:

Neoprene: Another synthetic rubber, neoprene offers good weather resistance and is a common alternative to EPDM in some applications. It may be slightly less UV resistant than EPDM in the long run.
Silicone: Silicone rubber offers exceptional temperature resistance and flexibility, often used in high-temperature or food-grade applications. It can be more expensive than EPDM.
Nylon: Nylon washers provide electrical insulation and vibration dampening. They are not primarily designed for weather sealing but can offer some level of moisture resistance.
Fiber washers: Fiber washers, often made of cellulose fiber, swell when wet, creating a seal. They are commonly used in plumbing applications but are less suitable for exposed outdoor environments compared to EPDM.

Liquid Sealants and Tapes: In some situations, liquid sealants or sealing tapes might be used instead of or in conjunction with washers. These can be useful for sealing gaps or irregular surfaces. However, they generally don't offer the same level of mechanical fastening and long-term reliability as bonded washers for structural applications.

Choosing the Right Solution:

The best sealing solution depends heavily on the specific application, materials being joined, environmental conditions, and budget. EPDM bonded washers are a strong all-around choice for roofing and general outdoor fastening due to their excellent weather resistance, durability, and cost-effectiveness. However, exploring alternative integrated fasteners or washer materials might be beneficial for specialized needs.

My Verdict? EPDM Bonded Washers are a Smart Choice.

After decades in this industry, I've learned to appreciate solutions that are both effective and practical. EPDM bonded sealing washers tick both boxes. They offer a simple yet highly effective way to create reliable, long-lasting seals in roofing and outdoor fastening applications. Their superior weather resistance, durability, and ease of installation make them a smart choice for anyone looking to prevent leaks, reduce corrosion, and ensure the longevity of their projects.

Are they a game-changer? In the sense that they significantly improve the reliability and lifespan of roofing and outdoor structures – absolutely, yes. They might not be the most glamorous component, but they are undeniably essential for quality and peace of mind. And in my book, that makes them a winner.

EPDM Bonded Sealing Washers: Are They Really a Game Changer for Roofing and Fastening? Let’s Dive In.