When it comes to flat roofs or commercial roofing materials, you might have heard about EPDM roofs. EDPM is a common material that is often the first choice of both roofing contractors and property managers.
EPDM, short for ethylene propylene diene monomer, offers several advantages, one of them being its versatility and flexibility in installation. EPDM can be installed in different ways, one of which is our topic for today: ballasted EPDM roofs.
As a professional roofing company, we’ve worked with a range of roofing types, and we know ballasted EPDM is often misunderstood or overlooked. In this guide, we’ll go over everything to know about this less common roof type and why you should consider it for your building.
What Is an EPDM Roof?
First, let’s start with the basics. EPDM is a synthetic rubber roofing membrane that’s been around for decades. This single-ply membrane roofing system is primarily used on flat or low-slope roofs, like those on commercial buildings or modern-style homes. People love EPDM for its durability, flexibility, and long lifespan.
EPDM is a specially engineered synthetic rubber that offers exceptional performance in roofing applications. Its unique molecular structure allows it to withstand a wide range of environmental challenges, making it a go-to choice for architects and building managers seeking reliable roof protection.
Key features of EPDM roofing include:
- Weather resistance: Handles everything from blazing sun to freezing snow.
- Cost-effectiveness: A more affordable option compared to some other materials.
- Ease of repair: Small punctures or tears can be patched up fairly easily.
What Does “Ballasted” Mean in Roofing?
In flat roofing, the term “ballasted” refers to a system where the roof covering is kept in place by weight, rather than being glued or mechanically fastened to the structure. The weight—referred to as the ballast—can be made up of materials like smooth river stones, gravel, or even concrete pavers.
Coming to the topic at hand, a ballasted EPDM roof is a specific type of ballasted roof that uses EPDM as the base. In a ballasted EPDM system, the membrane is not adhered to the building but is instead loosely laid out across the roof deck and held in place by the ballast.
Think of it this way: the EPDM acts as a protective waterproof layer, while the ballast (typically smooth stones or concrete pavers) keeps it secure. Here are some features:
- Ballasted roofs can last for 25 to 430 years
- Ballasted EPDM generally costs around $1.50 to $5.50 per square foot
- EPDM membranes are available in multiple thicknesses, for example, 45-mil and 60-mil
Why Choose a Ballasted EPDM Roof?
Ballasted EPDM roofing isn’t the right fit for every building, but for the right kind of project, it’s a game-changer. Here are some reasons why this system might be worth considering:
Ballasted EPDM Roofs Are Affordable
Commercial roofs are generally bigger in area, so it’s even more important to keep overall costs in check. A ballasted EPDM roofing system can help with this. Because there’s no need for adhesives or complicated fasteners, installing a ballasted roof can be quicker and often less expensive than other EPDM systems. The savings in labor costs can be significant. EPDM, itself being less costly than other single-ply membranes like TPO and PVC, further keeps installation costs affordable.
Long-Lasting Performance
The weight of the ballast protects the membrane from wind uplift, which is particularly useful in areas prone to strong winds. Moreover, ballasted roofing systems have been proven to withstand wind speeds up to 90 miles per hour, providing exceptional stability in hurricane-prone regions. Plus, the ballast layer adds another protective barrier against UV rays and physical damage, helping your EPDM flat roof last even longer. Overall, you can expect a ballast EPDM roof to last for about 25 to 40 years.
Eco-Friendly Option
The stones or pavers used as ballast are natural materials, making this system more environmentally friendly. These materials can often be locally sourced, reducing the carbon footprint associated with transportation. Additionally, ballasted EPDM roofs often have excellent thermal performance, helping regulate the temperature in your building and potentially lowering your energy bills.
Simplicity in Repairs
If there’s ever a leak or damage to the membrane, repairs are straightforward. Professional roofers can typically complete most repair jobs within a few hours, minimizing disruption to the building’s occupants. The damaged area can be accessed by simply moving the ballast aside, without needing to tear up the whole roof.
What Are the Potential Limitations Of A Ballasted EPDM Roof?
Of course, no roofing system is perfect. It’s important to weigh the potential challenges of a ballasted EPDM roof before deciding.
Weight Considerations
The ballast adds significant weight to the roof structure. Commercial buildings must carefully evaluate their existing structural capacity to support the additional load. Engineers will need to conduct a comprehensive structural assessment to ensure the building can safely accommodate the ballasted roofing system without compromising its integrity.
Maintenance Challenges
While ballasted roofs are durable, the ballast itself can sometimes shift over time. This movement can create uneven distribution across the roof surface, potentially impacting drainage patterns and creating areas of potential membrane stress. Facility managers will need to implement regular inspections to monitor ballast placement and address any emerging issues promptly.
Not Ideal for Steep Slopes
Ballasted EPDM roofing systems are primarily for flat or very low-sloped roofs. Roofs with a pitch greater than 2:12 can experience significant ballast migration, making these systems impractical and potentially dangerous. If your home has a more traditional steep-pitched roof, this isn’t the right option for you.
Ballasted EPDM Roofing vs. Other Methods Of Installation
When exploring EPDM roofing options, it’s helpful to understand the main alternatives to ballasted systems: fully adhered and mechanically fastened EPDM roofs. These methods differ in how the membrane is secured.
Fully Adhered EPDM Roofs
In a fully adhered system, the EPDM membrane is glued directly to the roof deck using a strong adhesive. This creates a seamless, tight bond that provides excellent protection against wind uplift and water infiltration. Fully adhered systems are versatile and can be used on various roof types, including slightly more sloped ones. However, the installation process is more time-intensive and typically more expensive due to the cost of adhesives and labor.
Mechanically Fastened EPDM Roofs
Mechanically fastened EPDM systems use fasteners, like screws or plates, to anchor the membrane to the roof deck. This approach is quicker and more affordable than fully adhered systems and is particularly popular in areas with high wind exposure. While not as seamless as a fully adhered roof, a mechanically fastened system still provides reliable performance for flat and low-slope roofs. However, the fasteners may create more potential weak points compared to the other methods.
| Feature | Ballasted EPDM | Fully-Adhered EPDM | Mechanically Fastened EPDM |
| Installation | Quick, no adhesives or fasteners | Time-intensive, adhesives required | Moderate, uses fasteners |
| Cost | Lower upfront cost | Higher cost due to labor and materials | Moderate cost |
| Durability | Protected by ballast layer | Exposed membrane, vulnerable to UV rays | Similar to fully-adhered |
| Weight | Heavy | Lightweight | Lightweight |
| Ideal Use | Flat/low-slope roofs | Versatile for various roof types | Best for windy areas |
How Much Does A Ballasted EPDM Roof Cost?
The cost of a ballasted EPDM roof can vary depending on factors like the size of your roof, the type of ballast used (river stones, gravel, or pavers), and local labor rates.
On average, you can expect to pay between $1.50 to $5.50 per square foot, which makes it a relatively cost-effective option compared to other roofing systems. The lack of adhesives and fasteners helps keep installation costs lower, but keep in mind that structural assessments and potential reinforcements to handle the added weight may increase the overall expense. For an accurate estimate, a professional evaluation is essential.
Final Thoughts
Ballasted EPDM roofs are an often overlooked but highly effective roofing solution for flat or low-sloped roofs. They offer durability, cost-efficiency, and eco-friendliness, making them a smart choice for many property owners.
Installation: Leave It to The Professionals
One thing we want to stress: ballasted EPDM roofs are not a DIY project. Installing them requires expertise and experience to ensure the ballast is evenly distributed, the membrane is properly laid, and your roof is fully secure.
Our team of roofing experts at A. Fricker Roofing and Waterproofing has installed dozens of ballasted EPDM systems, and we can help determine whether this option is the best fit for your building. We’ll take the time to assess your roof, explain the process, and ensure you’re confident in your decision. Contact us today at (918) 402-7167.
