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Low Slope Roofing & Flat Roofing Options

Reliable American installs and maintains flat roofing of various types. Traditional flat roofing systems include modified bitumen and single ply. Another option gaining market share for their economic benefits are roof coatings.

Low slope roofing is rated anywhere from 10-30 years by the various product manufacturers. The determination of this longevity is how the new roof is installed. One thing is for sure, though, a low slope roofing system is all about the details. Neglect one detail and it'll leak for sure!

Let Reliable American install your low slope roof. We can guarantee your flat roof against leaks for up to 20 years! Ask us how.


Learn more about the Commercial Roofing process
Is your low slope roof failing?
"Warm Deck" vs. "Cold Deck" low slope roof designs.
Frequently asked flat roof questions
Hire the right Roofer

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versico tpo roof

Single Ply - PVC

PVC is short for Poly Vinyl Chloride and is quickly becoming the standard for low slope roofing applications in the Chicago and Northern Illinois area. PVC is a highly reflective and durable single ply membrane. What makes PVC great is its' ease of installation and it's heat welded seams, and most importantly PVC's proven logevity to last and last as a roofing membrane.

Hot air, forced from electric heaters, is used to fuse flashings and seams. In addition PVC is available in rolls larger than more traditional roofing systems meaning less seams. Less seams means less chance for failure. PVC is and excellent choice where minor ponding water may exist due to it's excellent lack of water permeability.

While PVC is available in multiple colors, it's most common is white. A White PVC roof is a highly reflective and is a cool roof, exceeding current energy efficiency standards and is an US Department of Energy, Energy Star rated roofing system. PVC may qualify for tax credits and LEED points. PVC is truly a "green roof".

PVC is commonly installed mechanically fastened or fully adhered. Due to its' lightweight nature it can often times be installed over existing roofing systems (when code allows). PVC is available in thickness ranging from 50 mils up to 80 mills. As you can imagine the thicker PVC will be more durable, last longer, is able to be warranted for longer terms, but also does require more up front investment.

If you want the very best thermoplastic roofing system installed, with the peace of mind that comes with heat welded seams, choose a PVC roofing system.

Single Ply - TPO


TPO is short for Thermo-Plastic Olephine, a TPO roof is similiar in looks to PVC however PVC has been on the market longer than TPO. The methods and manner in which a TPO membrane is installed is very similar to that of the PVC roof described above.

A TPO roofing system requires a slightly lower upfront investment when compared to PVC membrane. However the roof installation is almost exactly the same. If you are looking for a 10 year rated single ply roofing system, TPO may be the choice for you.

Did you know that white TPO & PVC membrane may qualify for consumer tax credits up to $1,500? Consult your tax professional or

versico pvc roofing

versico epdm ballasted roofing

Single Ply - EPDM

EPDM is similar to PVC in the fact that it is a single ply membrane, however EPDM is a rubber compound instead of plastic, like PVC. EPDM has a strong reputation for durability. With properly taped seams and detailed flashings, an EPDM roof can easily last up to 30 years. However, unlike TPO or PVC, the seams on an EPDM roof are treated with adhesive making the seams vulnerable over the long term and will eventually require maintenance.

EPDM is commonly installed mechanically fastened, fully adhered, or ballasted. Ballasted EPDM roofs are very economical on large projects, when the structure can support the weight of the rock ballast.

EPDM is available both reinforced with polyester scrim and non-reinforced in thick nesses ranging from 45 to 90 mills. 90 mill EPDM is the only EPDM membrane eligible for a 30 year system rating.

Definitions of Single Ply installation methods:

Fully adhered - a roofing system or a component of that system that is glued in place or otherwise secured with adhesives. Fully Adhered roofs carry system ratings of 15-20 years (30 years on EPDM with proper construction of the roofing assembly).
Mechanically fastened - a roofing system or a component of that system that is secured in place using fasteners of some kind. Often these fasteners are button head nails or screws with plates. Regular shingle style roofing nails are not acceptable. Mechanically fastened roofs carry system ratings of 10-15 years.
Ballasted - a roofing system that is not fastened nor glued in place. Instead the roof is weighted in place by the application of washed river rock, manufactured concrete pavers or other media of substantial weight. Ballasted single ply roofs carry system ratings of 10 years.
 Mill Thickness can be translated into inches for better understanding. Since 1 mil = 0.001" (or 1/1000 of an inch; hence it being called a "mil"), 45 mils = .045". In fractions a 45 mill membrane would equal approximately 1/22".

Modified Bitumen

Modified bitumen is perhaps the most common of residential low slope roofing systems. Modified bitumen is installed in 3' rolls, either torch applied using flame heat to weld the cap sheet to the base sheet(s) or self adhering using factory applied adhesives on the various components. The duration of your warranty term on modified bitumen is determined by the number of layers.


firestone modified bitumen rolls

Quick specs for a typical modified bitumen roof assembly is as follows:

1 layer of base and 1 layer of smooth black modified bitumen - 10 year system rating.
1 or 2 layers of base with 1 layer of smooth modified bitumen and an application of an approved reflective coating - 12 year system rating. (Please note that this reflective coating may require periodic maintenance or re-application to achieve a 12 year life cycle)
2 layers of base with 1 layer of granulated modified bitumen - 15 year system rating.
1 or 2 layers of base with a smooth modified bitumen mid-ply and a granulated modified bitumen cap sheet - 20 year system rating.

People often wonder why their modified bitumen roofs last only 10 or 12 years and do not understand that is usually what most other roofers may be offering.

A note about modified bitumen in regards to city of Chicago energy and reflectivity codes; a smooth black modified and most normal granulated modified bitumen membranes will not meet current city of Chicago reflectivity requirements.


Choosing a roofing system for your property may be overwhelming if you don't know the pro's and con's of each membrane. There are no one size fits all solutions. Each low slope roofing membrane may be superior for some conditions, while inferior for others. The determination of this longevity is how the new roof is installed. For example a mechanically attached 45 mil single ply roofing system may be rated to last 15 years, while a fully adhered 60 mil roofing system with insulation may be rated to last 20 or 30 years.

Liquid Applied Roofing Systems (Coatings)

To learn more about liquid applied roofing systems please read about roof coatings. Liquid applied roofing systems are a wonderful alternative when a tear-off isn't necessary or won't fit in the budget. Liquid applied roofing systems can be expected to last 5-15 years.

With certifications from various manufacturers such as Genflex and CertainTeed, Reliable American can get the job done right and offer long term No Dollar Limit warranties! Contact us for your free inspection and estimate. We can guarantee your flat roof against leaks for up to 20 years! Ask us how.

Quality Work Ahead!(tm)

Learn more about the Commercial Roofing process and allow us to
determine which roof is the right roof for your property. Contact us today!

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Glenview, IL
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