In our overview of Flat Roofing Technologies: Part I – BUR, Tar & Gravel and Modified Bitumen, we discussed the older and in many ways inefficient types of flat roofs, that are not only outdated by today’s standards, but also have a short life cycle expectancy. Moreover, they pose numerous obstacles when it comes to repairing those flat roofs, as discussed in our Flat Roof Repair guide. See our comparison of two seemingly similar, yet very different in their nature flat roofing types – PVC and TPO roofs below.

In Part II we will take a look at the newer, more advanced roofing technologies, and explore the advantages and disadvantages of each single-ply roofing technology commonly used today.

What is single-ply flat roofing?

There is a lot of confusion about single ply membrane roofing. Many people think that any ‘single ply’ is the answer to their flat roofing problems. This however is far from being the truth. In reality, single-ply roofing membranes have only one thing in common – that is they are single ply or just one layer of membrane that is a water proofing barrier. The similarity stops there.

Single ply membrane formulation, or the components a membrane is made of, is what makes the difference between different types of single-ply flat roofing membranes. Single ply roofing membranes come in various widths, ranging from 6 to over 18 feet. In theory, the wider the membrane is, the less overlapping seam you have, thus reducing the possibility of leaks. The reality is different however, and most commonly used membranes do not exceed 10 feet in width.

The most crucial aspect to the reliability and longevity of single ply roofs is the method of attaching overlapping seams together. That is where 99% of flat roof leaks occur. Therefore, having permanently attached seams is the most important factor in the longevity of a flat roof installation. We will discuss it in more detail as we review different single ply roofing technologies.

IB Flat Roof installation in Weston, MA

Single-ply membrane installation methods:

Single ply membranes are installed either as fully adhered or mechanically attached systems depending on each roof’s condition, and other factors, as well as an installer’s preferences in some cases. Underneath the membrane there s usually a separation barrier and/or some sort of insulation board. Most common insulation is ISO or EPS foam board. Both types have an R-value ranging from 4-R to 6-R per 1 inch of insulation thickness.

Mechanically attached installation uses heavy duty screws and barbed plates to hold the membrane down tightly, and is not affected by possible ISO de-lamination. The membrane is attached using 12″ O.C. pattern with perimeter sheets attached 6″ O.C. This ensures that even the hurricane-type wind will not tear off your roof. Mechanically attached installation method does not require the use of heavy and expensive ballast, and is a preferred choice if your building is located in the high-wind area, such as along the coast line or on a high hill.

Fully adhered single ply membranes are glued to the fiberglass sheet laminated to both sides of the ISO insulation, which is in turn attached to the roof deck. While quick and simple, the fully adhered method has one serious disadvantage. If condensation forms underneath a roofing membrane, which often happens and may be caused by improper ventilation of the roof deck, it will ‘de-laminate’ the ISO board and/or adhesive that is holding membrane in place. If the membrane becomes loose, it is prone to wind blow-off, which will leave your roof unprotected. Results of such blow-off will be catastrophic not only to your roof, but to the entire building. While this is rarely the case, it is still a possibility – a gamble you might not want to take.

More common problems with fully-adhered single-ply flat roofing systems (Mostly EPDM rubber) are defects in glue/adhesive application that cause bubbles, badly glued seams and as a result, a very unpleasant view and more often then not, roof leaks. The image bellow demonstrates a defective Epdm rubber application.

Find out more information on why you should avoid installing EPDM rubber roofing on you home and how residential roofing contractors are trained to install rubber roofs.

Three most common single-ply roofing types:

Today, single ply roofing has become the prime choice when it comes to flat roof replacement. More and more roofing contractors are switching from old roofing types like BUR, Asphalt, and Tar & Gravel roofs to single-ply membrane installation, which is easier, safer and faster. Single ply roofing installation does not use the torching used in Modified Bitumen roofs installation, and therefore there is no fire hazard/possibility to bur down your home / business.

There are 3 most-used single ply membrane types present on the market today: PVC/CPA, EPDM rubber and TPO. While these abbreviations probably won’t tell you much, about these roof types, bellow we provide a brief summary of each of these technologies.

PVC (CPA) Roofing:

• PVC – Polyvinyl Chloride – a thermoplastic membrane utilizing a reinforcement scrim between the two plies of equal thickness (IB roof only). Top ply contains Cool Roof pigments, UV stabilizers, and other components to extend the life of the membrane. Bottom ply contains PVC ingredients to provide consistent weld of top and bottom plies and fillers. Material Warranty Period: Up to 25 years Commercial / Lifetime Residential. PVC roof system life expectancy: 30+ years.
• Special Notes: For a complete overview of IB flat roofing products for residential, commercial and restaurant use, as well as installation method and roofing accessories refer to our IB Roof products page.

TPO Roofing

• TPO – Thermo Plastic Olefin – a thermoplastic membrane utilizing a reinforcement scrim between the two plies. 35/65 % thickness for top & bottom ply respectively. Top ply contains Cool Roof pigments, UV stabilizers, and other components to extend the life of the membrane. Bottom ply contains TPO ingredients to provide consistent weld of top and bottom plies and fillers. Note that the top ply is about half the thickness of the bottom ply. Yet the top ply is the one that makes the roof long-lasting. IB PVC has a 50/50 or equal thickness of top/bottom ply.
• Material Warranty Period: Up to 20 years Commercial / NO Residential. TPO roof system life expectancy – 7 to 20* years. You should know that there is not a single TPO installation in existence in the USA, that was produced in North America and is older than about 15 years. Therefore it is unknown how long a TPO system will perform without any leaks*.
• Special Notes: * TPO roof systems are under continuous development by numerous manufacturers, who constantly change the TPO formulation to achieve the lowest cost with acceptable performance. While it is understandable that businesses always look to save money and to reduce costs, these constant TPO development process is being conducted, often at the expense of the roof owner. A TPO roof from the same manufacturer will most likely NOT be the same as the one produced few years before or after. Also the quality of different batches of TPO membranes may be questionable, as some TPO producers release the product to the end user without getting the UL and similar approvals/certification, as the formulation changes too often. Refer to our comparison article of PVC vs. TPO to find out more about the TPO problems / short-comings.

EPDM Rubber

• EPDM Rubber – Ethylene Propylene Diene Monomer – a rubber-like black membrane, usually non-reinforced. Most common application method is a fully adhered (glued down) membrane with glued seams / flashings.
• Material Warranty Period: Up to 40 years Commercial / NO Residential. EPDM roof system life expectancy – 10 to 15 years. Although the material warranty goes up to 40 years for a 90-mil Epdm from some manufacturers, it does not cover the seams. Failing seams are the main cause of EPDM roof leaks followed by ponding water, for which EPDM has no warranty either.
• Special Notes: EPDM is the least expensive single ply roofing type and requires no special equipment to install it (unlike PVC and TPO which require hot-air welding equipment) and thus is the first choice for roofing contractors entering the flat roofing market and asphalt shingle roofers, who ‘install rubber here and there’. Although many commercial roofing companies also use EPDM, they usually do not perform Residential installations so many times a home owner deals with a Part-Time flat roofing company.

Badly installed Rubber Roof:

Please note that there are many manufacturers of all three types of roofing, and each has their own formulation / manufacturing process / warranty conditions and periods, etc. Therefore we only provide a general summary for each of those roof types. Also, since our specialty is installation of IB roofs, when we use the term PVC or CPA we refer to IB PVC Roof (CPA or Co-Polymer Alloy is the way IB Roof Systems refers to its PVC product. IB membranes are 100% ‘compatible’ with other PVC products).

Common single-ply flat roofing choices: CPA/PVC membrane – IB Roof

CPA/PVC single play flat roofing membrane made by IB Roof Systems is by far, the best choice for any type of flat roof. The main advantage of IB’s CPA/PVC membrane is that the seams are Hot Air welded creating a physical bond between the sheets, which is stronger than the membrane itself. Such seam is a permanent seal, ensuring that there will be no leaks even if you have puddles of ponding water on your roof (which by the way is covered under IB’s warranty, unlike other types of flat roofing membranes that only cover the defects in material). IB’s CPA/PVC white membrane is the true energy efficient Cool Roof, this will not only give you years of worry-free performance, but will actually save you money in reduced energy costs. IB also offers a variety of colors, many of which will also qualify to carry a Cool Roof label. But the main factor speaking in favor of IB’s CPA/PVC membranes, is that they have historically proven to last over 25 years without a single leak!

Learn more about IB’s outstanding single ply flat roofing membrane, its advantages, and many choices for Residential, Commercial and Restaurant use.