Choosing the Best EPDM Membrane Thickness for Your Flat Roof

Selecting the right thickness for the EPDM membrane on your commercial building’s roof is undeniably the the most important decision you’ll make during your flat roofing project…

EPDM membrane thicknesses vary in cost and protection, so it’s important to pick the size that’s best for your specific situation. To learn which is best for your building:

  • Start by getting an visual understanding of how thick each membrane option really is
  • Continue on to learn which thickness is best for your specific situation
  • Call Roof Hub for an EPDM roof replacement estimate: 857-237-7648 

What do Different EPDM Thicknesses Look Like?

Use Roof Hub’s EPDM thickness visualization tool to see what the most common rubber membrane sizes look like compared to a credit card for reference. A 60 mil membrane is recommended for most flat roof installations.

45 mil
Credit card is approx. 85 mil tall (represents 85 mil thick EPDM)

The Significance of EPDM Membrane Thickness in Roofing

EPDM membrane thicknesses matter more than the manufacturer or any of the other materials, and if you choose the wrong one, then you may be headed towards more headaches down the road than are necessary. But what thickness is best for you roof?

Best EPDM Rubber Roof Thickness for Most Commercial Buildings

The best EPDM thickness for most flat roofs is 0.60 mil, with some exceptions if: 

  • You’re selling your property soon.
  • The rooftop will see high foot traffic
  • The building has heavy industrial use
  • You’re roofing in a moderate climate (unlike roof replacement in Boston)

But whatever you choose, remember that the choice you’re making impacts the flat roofing system’s most important component. But don’t stress! When it comes to choosing how thick your rubber roof membrane will be, we got you covered even more than a .90 mil membrane ever could. How fun.

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Selecting the Right Membrane Thickness: Options and Applications

The gauge of your EPDM roof membrane plays determines your roof’s:

  • Durability
  • Longevity
  • Options for future use of the roof space
  • Protection against environmental factors

Rubber membranes come in a range of thicknesses, from too skinny, to just right, to unnecessarily hefty: 

  • 45 mil (too thin for most)
  • 60 mil (perfect for most)
  • 90 mil (too thick for most)

Let’s figure out more about your roof, then decide what’s best for your property. 

Alternatively (if you’re in Boston), you can stop reading now and call us. We answer 24/7, and you’ll quickly learn why building owners and property managers all over Massachsuetts frequently recommended Roof Hub for flat roof replacement: 857-237-7648

45 mil (1.14 mm) EPDM Thickness

45 mill thick EPDM membrane section summary image

45 mil rubber membranes are not the recommended choice for most flat roofing installations, but there are a few situations where this membrane thickness can be sufficient:

  • Residential roofs in areas with mild climates.
  • Small commercial buildings in mild climates with no foot traffic.
  • Low-slope roofs with minimal exposure to harsh weather conditions.
  • Low slope porch roofs and flat roofs over a three season porch or door entryway

This thickness is a standard choice for quick and simple roofing projects, so if your roof replacement doesn’t feel like it should be quick or simple, then this isn’t the size for you…

EPDM membranes that are 1.14mm thick offer cost efficiency and rarely much else. They’re mostly suitable for buildings in regions with moderate weather conditions like the Mid-Atlantic United States as it can withstand moderate wind speeds and rainfall but doesn’t perform well with intense pounding from the elements.

Installation techniques for 45 mil EPDM membranes

The 45-mil composition can be fully adhered, mechanically attached, or ballasted. It is commonly used in fully adhered and mechanically attached systems for low-slope roofs in moderate climate zones and should be avoided in the Northeast, unless you plan to sell the property soon.

Replace your flat roof when flipping the property

A common use of this thickness in the Northeast is when the owner is selling the property soon and looking to do the complete the project as cheaply as possible. If you have an original tar and gravel roof under the membrane, then this can sometimes be sufficient in protecting the roof for up to but not more than 10 years.

Many Real Estate Agents would recommend upping the thickness choice to 60 mil and advertising the long-term performance of the roof to potential Buyers. Knowing that they won’t need to upgrade the flat roof for at least 15-20 years adds significant perceived value for most Real Estate transactions in the Commercial Sector.

60 mil (1.52 mm) EPDM Thickness

60 mil thick EPDM membrane section summary image

Here we are, the most popular thickness you’ll find; 60 mil.

Designed to withstand much harsher conditions than 45 mil, 60 mil EPDM rubber membranes offer the perfect balance between cost and long-term protection from the elements. They’re ideal for areas with severe storms and in the off chance that your property is located in an area with frequent debris flying through the air, then you can depend on it to protect you there too. 

60 mil’s increased resistance to damage makes it the smart choice for properties like:

  • Flat roofs in Massachusetts and Connecticut.
  • Industrial facilities that do not have heavy foot traffic on the roof
  • Roofs in coastal areas that are exposed to corrosive elements like saltwater.
  • Commercial buildings located in regions prone to strong winds or heavy rainfall.

Installation techniques for 60 mil EPDM membranes

The 60-mil EPDM membrane is commonly used in fully adhered and mechanically attached systems for commercial buildings located in locations prone to strong winds, heavy rainfall, and possibility of debris impact.

GenFlex 60 Mil EPDM Membranes

GenFlex is a notable rubber membrane manufacturer offering 60 mil membranes. This data sheet details their GenFlex II EPDM Membrane product. It’s made of Type I vulcanized rubber and complies with ASTM D 4637-04 standards, a test providing property limits to characterize the EPDM sheeting.

The GenFlex II membrane demonstrates impressive tensile strength, with a minimum of 1305 psi, and can elongate up to 450%, showing its flexibility and durability under stress. Its reflectivity is notably low at 6%, while the emissivity is high at 0.87, indicating the rubber’s ability to absorb most sunlight, helping buildings with thermal management, an ever-increasing factor in Commercial Roof Replacement.

Roof Hub is an Official “Certified GenFlex Licensed Applicator”, offering GenFlex-approved EPDM installations from our regional offices in Boston, MA and East Hartford, CT. Our service area includes all of Massachusetts and Connecticut. If you need a flat roof replacement estimate, call us: 857-237-7648.

90 mil (2.29 mm) EPDM Thickness

summary image for 90 mil epdm thickness roofing section content

For the most demanding roofing scenarios, the 90-mil (2.29 mm thick) EPDM membrane stands as the toughest choice, but not one that’s right for everyone…

90 mil is only necessary for commercial settings that push their roofing materials to the limit, justifying the additional and oftentimes unnecessary cost. Roofs that we recommend the 90 mil thickness for include:

  • Large commercial buildings in areas with extreme seasonal weather conditions, like the heavy winter-long snowfalls in Northern New England cities like Burlington, Vermont or frequent hailstorms in the Midwest.
  • Commercial buildings where an additional level of protection is required like for Airport roofing and Hotel roof replacement.
  • Industrial facilities with high foot traffic and heavy equipment, regardless of climate.
  • Roofs that require ballasted systems, where the membrane is loose-laid and secured with a layer of rock (typically river stone, pavers).
  • Building owners who don’t care about installation cost and simply want the thickest material on the market.

How much do 90 mil membranes cost?

Why wouldn’t everyone just choose this thickness, if its the most durable?

With durability comes cost, with 2.29mm thick membranes being the most expensive out of all the options. They normally cost 40% more than 60 mil options, which are sufficient for most flat roofing systems.

Installation techniques for 60 mil EPDM membranes

If you have a ballasted system, then you’ll want an 90 mil thick membrane. A ballasted system is one that’s loose-laid and secured with a layer of stone or pavers. It is suitable for large commercial buildings in areas with extreme weather conditions and heavy foot traffic.

GenFlex 90 Mil AFR EPDM Membrane

GenFlex’s 90 mil AFR EPDM Membrane is designed to increase the durability and effectiveness of fully adhered roof systems. This specialized membrane gives commercial roofs a substantial 90 mils of unobstructed waterproofing, a feature that separates it from other rubber membranes that normally only include reinforcing fabric, which may compromise waterproofing efficiency under high-stress industrial roof settings. The AFR membrane is formulated as a Low Slope Fire Retardant (LSFR) compound, adding to its suitability for a wide range of flat roofing applications. For technical specs, check out the product sheet here.

All options listed above are available in both reinforced and non-reinforced membranes.

Benefits of Thicker Membranes

The thicker the rubber, the more protection your roof will have, and the more additional benefits begin to add up. In fact, the only benefit of a thinner membrane is cost savings. 

Rubber roofing  that’s thicker gives you:

  • Better waterproofing
  • Less impact of foot traffic
  • Longer EPDM rubber roof life expectations
  • Improved resistance to corrosive elements
  • Increased compression resistance and energy absorption
  • Increased resistance to roof punctures and membrane tears
  • Better roof insulating properties, lowering heating and cooling costs

The Scientific Benefits of Thicker Rubber Roof Membranes

Are thicker membranes always better?

While there are no specific studies about EPDM thickness, adjacent real-world case studies about EPDM in general suggest that a thicker membranes do offer greater resistance to physical damage, which logically translates to a longer lifespan for your rubber roof.

According to M. Sadighi, S. Salami with the Central European Journal of Engineering, thicker EPDM membranes are superior across many factors including energy absorption, compression, and impact resistance.

Energy Absorption

One of the key properties tested in Sadighi and Salami’s study was how much energy foam materials could absorb. This is similar to how a thick gym mat can absorb more impact than a thin one, making it safer to land on. 

Thicker EPDM membranes like 60 or 90 mil can absorb more energy upon impact compared to thinner ones like 45 mil, meaning that if something hits or presses against the rubber like the step of a foot, a dropped tool, or more severely a fallen tree, the thicker membrane will do a better job soaking up that impact energy, reducing the force that might otherwise be transmitted through the material.

Compression Resistance

When the Journal’s study discussed how the foams behave under compression (while being squished), it’s like testing how much a foam mattress squishes when you sit on it. A thicker EPDM membrane will likely resist compression better than a thinner one. This means it can handle more pressure or weight without being crushed or losing its shape too much.

Impact Resistance

The study also looked at how these materials behave under a slow impact, like being hit by a slow-moving object. Thicker EPDM membranes will generally provide better protection against such impacts. It’s like wearing a thicker helmet – it provides more cushion and protection with can be important if your rooftop sees consistent activity or has industrial machines or HVAC units that necessite frequent repair or replacement.

Making an Informed Decision on EPDM Thickness

Choosing the optimal EPDM membrane thickness for your commercial roof is not a decision to take lightly. It’s about matching your building’s uniqueness with the right balance of cost, durability, and protection. 

The most effective roofing strategy is one that takes into account all relevant factors—from material properties and installation methods to how your local climate influences what your roof will feel from month to month and year to year. 

Are you prepared to choose the EPDM membrane that will best protect your investment for years to come?

Thick Membranes Installed Across New England

How thick? 

However thick you want it 🤷 

Roof Hub has completed hundreds of flat roof replacements with 45, 60, and 90 mil EPDM membranes using the fully-adhered application method across New England. We can help you choose the membrane that’ll protect your building for the next 20+ years and beyond.

From Boston neighborhoods like Dorchester Boston and Roxbury Boston, to Downtown Boston areas like the North End and Financial District, to close by towns like Milton and North Quincy, we’re the preferred flat roof replacement contractor in Greater Boston. 

Our service area includes all of Massachusetts and from our new location in East Hartford, CT we can service all of Connecticut.

Call 857-237-7648 to get started, or click here to submit your EPDM estimate online.

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