EPDM Roof Membrane Installation Types Compared: Best Application Methods

When it comes to protecting flat roofs from the elements, EPDM rubber roofing membranes stand out for their durability, versatility, and cost-effectiveness when compared to other flat roof materials like TPO.

However…

The long-term effectiveness of your EPDM roofing installation depends on choosing the best installation method for your building’s needs and the region where you live.

There are three main types:

  1. Ballasted
  2. Mechanically-Fastened
  3. Fully-Adhered

In most cases, Roof Hub recommends the fully-adhered application method because it provides the strongest bond between the membrane and roof deck for maximum weatherproofing.

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There are very few cases where we recommend any other application style, but one case is when the roof deck is concrete or has a lot of irregularities. In this case the mechanically fastened method may provide more versatility to securely fasten the membrane. Our recommendation on ballasted application is simply to avoid it, however, we will cover all three methods in detail below.

Choosing the Best EPDM Roof Installation Method for Your Flat Roof

Several factors should guide the selection of the best EPDM roofing installation method:

Climate

Climate is a major consideration. In cold northern regions with heavy snow loads or high winds, a mechanically fastened system may be preferable for the added uplift resistance it provides. In hot southern climates, adhered options excel since heat can loosen mechanical fasteners over time.

Roof slope and geometry

Roof slope and geometry also impacts the decision. On low-slope commercial roofs under 2:12 pitch, ballasted and adhered EPDM can conform well. However, steeper sloped or curved roofs benefit more from mechanical fastening.

Building use

Building use is important – hospitals and data centers demand incredibly resilient assemblies to prevent leaks, making fully adhered the prime choice. Schools, warehouses, churches, and hotels may value faster installation from mechanical fastening to minimize disruption.

Cost

And cost differences can steer the decision. Fully adhered EPDM has higher material and labor expenses compared to the other techniques. Building owners only prioritizing a cheap install may lean toward ballasted or mechanically fastened designs instead.

Consulting a qualified EPDM roofing contractor is wise to determine the best method for a building’s specific demands. Expertise is the only way to identify the most suitable long-term solution on a case-by-case basis.

Ballasted EPDM Roof Installation

Chapter 15 of the Massachusetts State Building Code for Roof Replacement, which covers Roof Assemblies and Rooftop Structures, defines ballast as:

“…large stones or paver systems or light-weight interlocking paver systems and is used to provide uplift resistance for roofing systems that are not adhered or mechanically attached to the roof deck.”

Ballasted EPDM roofing installation is a cost-effective method that uses stones to secure the membrane, providing UV protection and flexibility for thermal changes. However, it may require more maintenance and additional support for the roof deck, on top of being a less secure choice than other options.

Process of Ballasted Installation

The ballasted installation method secures the EPDM membrane using weights, typically smooth round stones or pavers.

First, the roof deck is prepared by installing any necessary insulation or cover boards and by making sure the surface is clean and dry.

Next, the EPDM membrane is loosely laid over the roof deck without any attachment.

Then, round stones ranging from 1.5-3 inches in diameter are loaded on top of the membrane at the rate of 10-15 pounds per square foot.

The stones can be installed in a single layer or in multiple layers with filter fabric separating each layer. The ballast holds the EPDM sheet in place and provides protection from wind uplift and ultraviolet radiation. Proper spacing between the roof edges and ballast is critical for wind resistance. Any rounded protrusions on the roof, like vents or skylights, also need increased ballast around the perimeter to prevent the membrane from blowing loose.

Advantages of Ballasted Installation

The primary advantage of ballasted EPDM roofs is cost-effectiveness.

By eliminating mechanical fasteners, adhesives, or specialized equipment, both material and labor expenses are reduced.

Ballasted systems also inherently provide excellent UV protection for the membrane since the stones block close to 100% of sunlight exposure. The loose-laid design and flexibility of the EPDM allow for thermal expansion and contraction without stressing the material. And if you love rocks, the round stones can serve an aesthetic purpose, too, creating a decorative roofing surface.

Disadvantages of Ballasted Installation

While inexpensive initially, ballasted roofs require more frequent maintenance over time, the membrane can become damaged from wind-blown debris around the ballast or from workers walking on the stones during inspections and repairs. The constant weight also causes faster weathering compared to other EPDM installation methods, such as fully adhered, which we will discuss below.

Ballast displacement from storms or building sway must be routinely checked. And if re-roofing is ever required, the heavy stones make removal more challenging and expensive. Imagine lugging thousands of rocks up to the top of the roof. You do this by hand or you rent a crane.

Either option is time-consuming or expensive, adding to the project cost and getting you closer to what a longer-lasting fully adhered membrane would cost…

There are also building code requirements on maximum ballast loading per square foot to avoid over-stressing the roof deck structure. You’ll need to be mindful of these, and codes by locality can vary in Boston. So additional deck reinforcement may be needed in some retrofit applications, eliminating cost savings.

Ballasted Low-Slope Roofing Codes in Boston, MA

In Massachusetts, low-slope roofs are those with a slope of 2:12 or less. For low-slope roofs installed in the Bay State, according to Section 1504.4 (Ballasted Low-Slope Roof Systems) of the Massachusetts Building Code, these “single-ply roof system coverings must be installed in accordance with Sections 1507.12 and 1507.13 shall be designed in accordance with Section 1504.8 and ANSI/SRPI RP-4.”

Sections 1507.12 and 1507.13 of the International Building Code cover Thermoset Single-Ply Roofing and Slope, respectively.

ANSI is the Approved American National Standard, and SRPI is the Single-Ply Roofing Industry Association. We won’t dig into the details here on all the codes here because we don’t recommend Ballasted systems for flat roof replacement in Boston or Connecticut, so if you want to learn more, check out their Wind Design Standard for Ballasted Single-ply Roofing Systems PDF.

Mechanically Fastened EPDM Installation

The mechanically fastened method involves securing the EPDM membrane and underlying insulation to the roof deck using plates and fasteners.

Compared to ballasted systems, the mechanically fastened approach provides added strength, versatility, and easier wind uplift compliance because of the membrane is fastened down and not loose laid.

Process of Mechanically Fastened Installation

The process begins by installing insulation boards over the roof deck, which can involve adhering or mechanically fastening them.

Next, the EPDM membrane sheets are unrolled over the insulation, with adjoining sheets overlapped and spliced together using seam tape.

Fastener Use and Spacing

The membrane is then secured to the roof deck using fasteners and seam plates that penetrate the membrane and insulation into the deck.

Typically, fasteners are spaced 12-18 inches apart throughout the entire area of the roof to provide wind resistance. The spacing of fasteners in mechanically fastened roof installs can vary by region. Finally, the perimeter edges and penetrations are flashed to complete a watertight seal.

Advantages of Mechanically Fastened

There are a few benefits to mechanically fastened EPDM roofs when compared to ballasted installs:

  • Better wind uplift resistance due to the direct fastening of membranes. This makes it easier to achieve FM wind speed ratings.
  • Faster to install than fully adhered options since less adhesive work is required.
  • Avoid potential odor issues associated with adhesives during application.
  • Accommodates lightweight insulation options like polyiso boards.

Note that the mechanically fastened method can be used with any single-ply membrane type beyond just EPDM, such as TPO.

Disadvantages of Mechanically Fastened

While quite robust compared to using ballast, some limitations to this application method exist:

  • More prone to fastener backout and potential membrane punctures over time. Proper fastener spacing, torque, and maintenance help mitigate this, but it is still not as strong as a fully-adhered installation.
  • Lacks the ability to conform to complex roof shapes and details as well as adhered options.

Overall, the mechanically fastened methodology is a fast and versatile EPDM installation technique able to provide adequate weather protection. Proper design and maintenance help maximize its structural reliability, and we rate it as the second-best installation method for single-ply EPDM membranes.

Codes for Mechanically Fasted Roofing in Massachusetts

Section 1504.3 (Wind Resistance of Nonballasted Roofs) of the Massachusetts CRM 780 states;

“Roof coverings installed on roofs in accordance with 780 CMR 1507 that are mechanically attached or adhered to the roof deck shall be designed to resist the design wind load pressures for cladding in 780 CMR 16.00.”

Chapter 16 of 780 CMR outlines Structural Design and is beyond the scope of an article about EPDM Roof Installation Types. However, it’s important to note that in Massachusetts and many other regions of the Northeast and USA, Structural Engineering codes vary significantly by state, county, and town. For example, Page 383 in Chapter 16 of the Massachusetts Building Code has a table outlining the different load requirements for snow, wind, and earthquakes for most towns in Massachusetts for building three stories or less. Here are a few examples:

  • Boston, MA roofing: Basic Wind Speed 105 MPH
  • Dedham, MA roofing: Basic Wind Speed 100 MPH
  • Hull, MA roofing: Basic Wind Speed 110 MPH
  • Milton, MA roofing: Basic Wind Speed 105 MPH
  • Milford, MA roofing: Basic Wind Speed 100 MPH
  • Natick, MA roofing: Basic Wind Speed 100 MPH

They’re not all the same. And not all roofs are the same…

If you’re looking for an EPDM roof installation in Massachusetts, you can start your Online Roof Replacement Estimate right now and have a free quote delivered within 24 hours. If you have a complex or especially large project like replacing a Hotel roof, then we will schedule a time to walk the roof with you and discuss your project options.

Fully Adhered EPDM Installation

The fully adhered application is an extremely secure EPDM rubber roofing installation method. The technique bonds the rubber membrane and insulation boards to the roof deck using water-based bonding adhesive, providing unparalleled wind resistance and stability.

While more labor-intensive than mechanical fastening, fully adhered EPDM offers the strongest and most durable assembly. This application method gives you the highest possibility of long rubber roofing lifespan.

Roof Hub exclusively installs full-adhered EPDM in Greater Boston because the fully-adhered method it provides the best long-term protection for Massachusetts homes and businesses. All roofs are installed in accordance with manufacturer specifications, such as Carlisle Syntec or GenFlex.

Process of Fully Adhered Installation

Top EPDM membrane manufacturer Carlisle SynTec explains the process for fully-adhered installations.

Installing a fully adhered EPDM roof begins with preparing the roof deck to a smooth, clean, and dry condition. Having a clean surface is important because the bonding adhesive will not adhere properly to dirty or uneven substrates.

Next, insulation boards are set into ribbons of bonding adhesive applied to the deck. The boards are rolled and pressed down to ensure full contact and adhesion. All insulation joints are then sealed with tape, a critical step because any gaps can lead to moisture intrusion, quickly compromising the system and the building’s ceilings.

The EPDM membrane sheets are then unrolled over the insulation layer and positioned. After folding back half the sheet, bonding adhesive is roller-applied to both the underside of the membrane and insulation below. Once tacky, the sheet is rolled back down and broomed into place for total contact.

Adjoining sheets are overlapped by 6 inches or more, compared to 3 inches or more for other application types. After overlapping, the sheets are then spliced, sealed with seam tape, and adhesive applied at the splice edge. This process is repeated to provide a protective, seamless single-ply membrane and to finish the project, all flashing and detailing is completed once the field membrane is installed.

Advantages of Fully Adhered Installation

Fully adhered membranes stand out for many reasons, most importantly:

  • Provides the strongest uplift resistance and highest wind speed ratings to meet building codes.
  • Eliminates membrane billowing, flutter, and pull-out risk (compared to loose-laid systems).
  • Accommodates greater slope and irregular roof shape applications vs. mechanical fastening, which is important for older roofing systems or tar and gravel overlays.
  • Delivers exceptional durability and weathering performance for long-term flat roofing solutions.

Disadvantages of Fully Adhered Installation

Potential downsides to consider include:

  • Higher material and labor costs than single-ply alternatives result in a project cost of approximately 25% higher.
  • Adhesive odors, VOCs, and overspray require extra precautions, although new products are being released to mitigate this.
  • Strict weather condition requirements for adhesive application can be overcome by hiring a flat roof replacement contractor who has years of experience with project planning.

With proper planning and installation, fully adhered EPDM roofs provide maximum structural stability and protection. Their adhesive strength helps them excel in any rooftop construction environment.

Why Fully Adhered EPDM Is the Best Option

The fully adhered method stands above other options because of its long-term durability and performance. By bonding the membrane and insulation to the roof deck, fully adhered EPDM provides unmatched uplift resistance and weather protection over time.

Long-Term Performance and Benefits

These roofs can last 50 years in some cases. The full-contact bond eliminates membrane flutter, prevents moisture ingress, and accommodates greater slope/irregularity versatility. Wind uplift ratings can sometimes exceed 200 mph with high adhesion. Compared to mechanical fastening and ballast methods, fully adhered EPDM simply outperforms over decades of use, and it all starts with how the rubber membrane is installed on day one.

Addressing Installation Challenges

Fully adhered application brings added install complexity with weather-sensitive adhesives and increased needs for skilled laborers. But reputable contractors across New England, like Roof Hub specialize in these projects, having the skills, equipment, and experience to facilitate smooth installations with a crew trained on the best way to perfectly install an EPDM membrane.

The long-term benefits make the extra planning and coordination well worth it.

EPDM Installation Best Practices

Proper planning, preparation, and material selection are critical for successful EPDM installs. The only way to ensure that your roofing assembly meets code requirements, manufacturer warranties, and provides long-lasting weather protection, is to follow manufacturer specifications for every step of the installation.

Here are a few important points out of the many that flat roofing contractors consider when planning and completing a project:

Preparing for Installation

Before installing EPDM, the roof deck must be thoroughly inspected and repaired as needed. All surfaces should be clean, dry, and smooth. For adhered systems, decks must have the proper vapor retarder and be primed prior to adhesive application.

Environmental conditions also need to be considered. Temperatures should remain above 40°F for adhesives to properly cure. However, there are techniques for warming materials that can be used to allow rubber roofs to be installed in Winter when conditions are below 45 degrees.

Selecting the Right Materials and Accessories

Choosing EPDM membranes with a thickness of at least 60 mil will provide your roof better durability and performance under any type of weather. Matching insulation boards, fasteners, adhesives and seam tapes to the installation method (adhered, fastened, or ballasted) ensures system compatibility, boosting the integrity of the system as a whole.

Using membranes and components made by reputable EPDM manufacturers like Carlisle or GenFlex prevents issues related to manufacturer defects. And hiring certified EPDM contractors like Roof Hub can simplify material selection for you, as any roofer will have their go-to materials to be used for your specific type of install.

Following proper protocols and standards relevant to the installation method makes achieving EPDM roofing success much more straightforward.

Installation Safety Protocols

Roof safety should be a consideration for any Commercial Roofing project. Some safety considerations include:

  • Carefully following all product instructions and safety warnings, especially when using adhesives, primers, sealants, etc, as many contain flammable materials and health hazards.
  • Wearing protective equipment like safety goggles, chemical-resistant gloves, grip shoes, where appropriate. This prevents injury from slips, falls, and skin exposure to chemicals.
  • Allowing proper membrane relaxation time before adhering, as cold temperatures can cause bonding issues. Regardless of the roof type you’re installing, rushing the process can lead to immediate failure or long-term deterioration of the materials.
  • Storing adhesives and sealants within the temperature range required by the manufacturer’s specifications leading up to their use is critical. This range is normally from 59-77°F. Temperatures below 41°F are where you enter the danger zone because temperatures this cold can and will prevent proper curing and adhesion.

Whichever flat roofer you hire, make a commitment to only hiring a roofing contractor experienced with the installation requirements seen in your region. EPDM requires specialized materials and techniques to get maximum benefits, especially in challenging markets like Boston, MA.

Having a reliable roofer who follows a strict roof replacement process helps prevent mistakes, maximizing the value you get from your installation. Roof Hub prides itself on having the best value in New England, and we invite you to start your quote now to learn why.

Start Your EPDM Roof Installation Estimate Online

Start your project today by requesting a free estimate from Roof Hub:

https://myroofhub.com/start/

As a manufacturer-certified EPDM contractor, Roof Hub will evaluate your flat roof before recommending the best solution. Every roof project is different, even if the materials are similar! 

Our roofing team has installed hundreds of flat roofs in Massachusetts and Connecticut while maintaining 5-star customer, which we owe to our our seamless step-by-step replacement process. 

Let’s replace your flat roof. Contact us to get started: 857-237-7648.

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