Problems With TPO Roofing

Typical Price Range To Install new Flat Roof Average: $6,980 - $9,720
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While the popularity of TPO single ply membranes is continuing to grow among homeowners and commercial builders, there are a number of problems with this material you should be aware of.

Initially, TPO roofing was created to compete with PVC. Its original intent was to be a cheap welded seams reinforced membrane, to dominate the commercial roofing market based on price, while offering all the benefits of PVC (a high-end, long-lasting single ply membrane).

In this opinion piece, I compare Genflex TPO (not the most expensive product) to PVC made by IB Roof Systems (one of the most expensive PVCs).

 Cost to Install TPO Roofing
SQ. FT.
Prices
Low End
Mid Range
High End
Materials
$3327
$3914
$4971
Labor
$5292
$6226
$7907
Total Cost
$8619
$10140
$12878

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I will discuss how TPO has evolved from a fully welded system into a glued/welded product, and how it has failed to live up to its goal of being a less expensive, yet equally good alternative to PVC.

Failed Promise of TPO Roofing

25 or so years ago, large EPDM manufacturers decided to compete with the likes of Sarnafil, DuroLast and FiberTite, and take away their market share of high-end flat roofing. They began experimenting with TPO, which to this day is about 10% more expensive than EPDM and 10-30% less expensive than PVC (cost of membrane only).

TPO material install

They marketed the new material as providing: PVC roofing quality at the price of rubber.

Since these companies already had a large pool of commercial contractors and distribution in place, getting TPO to market wasn’t difficult. Roofers readily bought into the idea of a cheap PVC roofing membrane alternative. After a few years and millions of square feet purchased, TPO became the number 1 commercial roofing material installed (by volume).

Because PVC was seemingly a lot more expensive, many architects, specifiers and building owners chose TPO membranes (especially with the modern craze about Cool Roofs). Seeing the success of this product, many other manufacturers jumped on the band wagon.

TPO Roofing vs EPDM rubber vs PVC Membranes

EPDM rubber roof – On the lower end of the price spectrum there is EPDM rubber roofing – a time-tested black single ply membrane.

An EPDM membrane is pretty much the lowest priced flat roof.

Its main disadvantages are: lack of reinforcement (major shrinking after 15+ years), glued seams, and block color which is not a “Cool Roof”.

Sure, there is White EPDM, but it’s expensive, and very few suppliers carry it. Comparatively, white EPDM is at least as expensive as very good PVC.

Once EPDM seam adhesive starts to break down, repairs become very expensive, and it’s only a matter of time until that happens. Also, manufacturers strongly advise against installing EPDM in the winter, because glue freezes, and the roof may leak.

IB PVC Flat Roof Installation

IB PVC Flat Roof Installation

PVC – On the upper end of the price spectrum there is PVC roofing. It is a white, reinforced membrane with welded seams and flashings.

PVC can last well over 30 years. It is very easy to repair by welding a patch or re-welding seam voids. The membrane is reinforced, which ensures dimensional stability, and prevents shrinking or cracking (with the exception of the Trocal fiasco, which was an un-reinforced product, and could easily shatter in very cold weather, upon impact).

Most PVC roofs are white, with exceptional solar reflectivity. They also come in variety of colors for job specific requirements. And of course welded seams – once they are (properly) welded or fused together by heat, they should never come apart.

Even if there is a seam void, it’s easy to take care of it. Even all the flashing and edge metal is heat welded, so there is virtually no glue used for waterproofing.

This roof is fairly expensive compared to EPDM, but long-term (considering life span, maintenance, repairs and energy savings) it is more cost efficient than rubber.

 Cost to Install PVC Roofing
SQ. FT.
Prices
Low End
Mid Range
High End
Materials
$3827
$4502
$5718
Labor
$6086
$7160
$9093
Total Cost
$9913
$11662
$14811

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TPO Roofing Problems That Nobody Wants To Talk About

Remember welded seams? They are the MAIN benefit of PVC vs. EPDM Rubber – this was the primary selling point of TPO roofs.

Well, TPO membranes have problems. If the material was perfect – manufacturers would not change the formulation every few years. The main issues were (and still are) with the seams, among many other things. They simply did not hold as well as they were supposed to.

Want proof? About 15 years ago most TPO makers started offering PEEL & STICK tapes, flashing, as well as primer (fancy word for glue). Wait a second – that is how EPDM is installed??!!! You clean and then prime seams, add 3″ seam tape and roll the sandwich together, to make sure everything is glued properly.

TPO - glued peel & stick flashing

TPO Roof – glued peel & stick flashing

So since TPO is a welded system – why on earth would manufacturers offer Peel & Stick products for it??? The answer (in my opinion) is because welded seams failed!

Now, how come nobody wants to talk about this? Because manufacturers invested millions of dollars in building new manufacturing plants, marketing, incentives, and it would be very costly to admit that TPO did not live up to its promise.

TPO vs. PVC flashing details – glued – heat welded

Here we show how PVC and TPO manufacturers want contractors to install their product. Since for price comparison (below) we use GenFlex and IB Roofs, we also use their respective training videos. In the examples below, TPO is seamed with glue, whereas PVC is fully welded.

1) Edge metal flashing:

TPO material is glued to the roof with peel and stick primer & cover tape.

PVC drip edge is heat welded to the roof.

2) Pipe flashing:

TPO – peel & stick (glued) pipe boot.

PVC – welded pipe boot

3) Field seams:

TPO glued field seam (TPO seams also can be heat welded).

PVC welded field seams.

We can provide many more examples. However, the above is enough to see that TPO is not a true heat-welded system.

If it was, manufacturers would not come up with peel & stick / glued accessories. Because any non-factory glued seam will come apart (it’s just a matter of time), TPO in my opinion is not much better than EPDM rubber roofs, and is definitely not as good as PVC.

TPO Roofing Is Not Cheaper Than PVC!

If you examine the cost of TPO material, which without insulation, is about $1.66 per square foot (includes all necessary accessories) – it is not really cheaper than a PVC roof ($1.47 per square foot.), which it’s supposed to replace as the “less expensive alternative”.

NOTE: the section below will get very technical, because materials must conform to the installation instructions set forth by each manufacturer, and accessories should be used accordingly.

Let’s compare GenFlex TPO to the cost of an IB PVC roof – both 60 mil mechanically attached assembly. We quoted a 1575 sq.ft. roof using materials at the local Harvey Building Products, and got the following cost, after a 10% discount off list price.

We compare this to IB’s contractor price list from Feb 2017. Since the roof in question is 1575 s.f. we will need 2 rolls of 10×100′ of TPO and 3 full rolls of IB (6×90′) and 2 half rolls of IB (3×90′). Half rolls are used for perimeter sheet.

GenFlex installation instructions are unclear about the use of perimeter sheet. However, one 10×100′ roll can be cut into 3.3’x100′ rolls and used around perimeter.

NOTE: In 2006, GenFlex was acquired by Firestone BP. This means that GenFlex TPO roomembrane is the same as Firestone TPO, since it’s made in same factories. However, Firestone TPO is more expensive (I don’t know why).

Cost Of Genflex TPO – 60 mil white

Material Quantity Unit Price Cost / s.f. Amount
GenFlex 60 mil TPO (10′ x 100′) 2 rolls $562.50 $0.5625 $1125
GenFlex Peel & Stick Flashing (12″ x 25′) 1 roll $178.87 n/a $178.87
GenFlex Peel & Stick Cover Tape (6″ x 100′) 2 rolls $257.75 n/a $515.50
GenFlex Peel & Stick TPO Pipe Boot (1″-6″) 2 pcs. $33.44 n/a $66.88
TPO Peel & Stick Outside Corners 4 pcs. $29.70 n/a $118.80
TPO Primer (Glue for Peel & Stick) 5 ga. $31.27 n/a $156.37
Coated Roofing Screws – 4.5″ (1000 pcs) 4 ct $116.73 n/a $466.92
Barbed Plates (1000 pcs) 4 pails $117.45 n/a $469.80
Edge Metal – .032″ White Aluminum 17 pcs. $11.47 n/a $195.07
Total $1.66 / s.f. $3329.22

NOTE: GenFlex requires membrane fasteners to be spaced 6″ apart, due to larger sheet size. IB fastener requirement is 12″ apart. Because of this, we will double the amount of screws and plates to the GenFlex “order”.

Cost Of IB PVC – 60 mil White

Material Quantity Unit Price Cost / s.f. Amount
60 Mil White Full Roll (6′ x 90′) 3 rolls $588 $1.09 $1764
60 Mil White Half Roll (3′ x 90′) 2 rolls $294 $1.09 $588
IB Pipe Flashing (4” – 8”) 2 pcs $20 n/a $40
IB Outside Corners 4 pcs. $6 n/a $24
IB N/R Patches 5″ x 8″ (50 / bundle) 1 pack $29 n/a $29
3″ steel 45 Mil White Drip Edge (10′) 17 pcs $19 n/a $323
Coated Roofing Screws – 4.5″ (1000 pcs) 2 ct $116.73 n/a $233.46
2” Barbed Steel Seam Plate (1000 pcs) 2 pails $85 n/a $170
Total $1.47 / s.f. $3171.46

What we have is TPO installation using mechanically attached assembly, coming in at $1.66 per sq.ft.. and PVC at $1.47 per sq.ft. These figures are based on 2,000 sq.ft. of TPO and 2,160 sq.ft. of PVC.

If we consider that we need to install only 1,575 sq.ft. (45’x35′ roof used for above material quotes), our cost per square foot is nearly identical, but there will be a lot more left-over materials on the PVC side, that can be used on future jobs.

Things to keep in mind: IB is very expensive compared to other brands like Carlisle, Versico, Weatherbond, Flex, DuroLast, etc. It is on par with Sarnafil in price. Basically if you compare generic TPO price to generic PVC price, TPO is even more expensive!

The reason why TPO roofs cost more is you MUST use Peel & Stick flashing and primer (glue) for all penetration flashings, and for drip edge cover tape. With PVC, all flashings and cover tape are heat welded.

Now here is the “subjective” part: IB PVC is by far a much better product than GenFlex TPO. You can argue with it, but here is what roofers have to say about it!

Bottom line – TPO failed to be a cheaper alternative to PVC!

At $1.66 per square foot generic TPO is 13% more expensive than high quality brand name PVC, so the price war is lost.

TPO also lost its competitive advantage by using Peel & Stick flashing. It’s no longer a truly heat welded system, but is a hybrid of welded plus glued roof. Now, TPO is more like EPDM rubber with heat welded field seams.

Commercial size roofs – massive discounts

In the price example above we used a small size roof. Now what happens if the project is 10,000 or even 50,000 square feet? Sure contractors will get bigger discounts, but GenFlex TPO is already at $0.56 per square foot. How much lower can it go? Let’s say $0.50 or even $0.45 (highly unlikely). You still have massive amounts of expensive peel and stick accessories, primer, cleaner, and extra labor involved.

And be sure that IB Roof Systems and other PVC manufacturers also provide volume discounts. Once again – IB is one of the most expensive PVCs out there, and yet it’s cheaper than TPO. At the end of the day, the extra discounts on volume will be offset by extra labor, and the final material price will be nearly the same.

Why PVC Roofing Costs More To Install?

Honestly, I believe that higher quotes on PVC roofs are all superficial. Basically, since PVC has historically been a “premium” product and TPO/EPDM have always been “commodity” or cheaper alternative – contractors just charge more, because everyone does. As you can see from my analysis, both materials cost about the same, and installation is fairly similar.

It just like buying a BMW over Hyundai – the common perception is that BMW is a better car. The same goes for roofing – the common perception is that PVC is better than TPO, hence contractors charge more for it.


Average Flat Roof Cost:

Low End
$6815
Mid Range
$8769
High End
$11211

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This roofing guide is presented by Leo B.

I've been a roofer for 15 years, and specialize in Metal Roofing and Flat Roofing.

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18 comments on “Problems With TPO Roofing

  1. Leo,

    I personally enjoy PVC over TPO but this seems a bit misleading in today’s day in age to say that TPO’s have to have peel and stick installed accessories. I estimated and installed multiple 20 year TPO systems by primary manufacturers (GAF, JM, etc..) using no peel and stick products. 20 year NDL.

    Also- 4 pails of barbed plates for a 16 sq roof is just not possible. That’s a huge overestimation. Even though the screw pattern goes from 12″ O.C. to 6″ O.C. They would be spaced further out (every 10 feet versus every 6 feet).

    In general- the peel and stick products for TPO are aimed at newer contractors who don’t know how to heat weld yet or have generators/robots yet. They’re commonly part of 10 and 15 year systems and are NOT eligible for a 20 year system warranty.

    So overall I definitely agree with the conclusion you came to- but the reasons for leading the consumer there seem questionable at best.

    1. Bill,

      What do you use for edge metal on those TPO roofs, and how did you terminate field membrant to edge metal?

      Did you have parapets? Any drip edge (where water runs off into gutters)?

      This is where TPO was using peel & stick … on parapets you use caps anyway, so drip edge is not important in those applications. But if you still have to use glued cover tape, than TPO is no better than black/white rubber 🙂

      Honestly, I stopped following TPO advancements a couple of years ago, as I was never happy with its “current state” back in the day … maybe things have changed, but I doubt it.

      Leo

  2. None of these roofing materials will last half as long as a coal tar pitch roof. They also won’t last as long as a hot mopped or cold applied built up roof. Even modified bitumen is better than this stuff. All you have here are examples of temporary roofs that will have to be replaced in less than 20 years.

  3. i’m a roofing installer of Tpo for almost 15 years. never had any problems, fully adhered and mechanically fastened system. however, i did install “Duro Last” Pvc for a short time and had problems with cracking. i have gone back and repaired 10-15 year pvc roofs that dried out and cracked…., as a roofer, i noticed you are one sided, possible a Durolast sales rep. people get educated from a real source. pvc is horrible product!

  4. Does anyone know about GE Silicone 3500 Roofing system? I was going to do a TPO or PVC on an Apt Building but my Roofer says he highly recommends this 100% Silicone product over TPO or PVC.

  5. Hi. Do you have any information concerning damages that can occur to a tpo roof as a result of billowing of the membrane since only the seams are mechanically fastened in place with the membrane being loose laid?
    What is your name and your experience and qualifications, as I would like to reference your material if you approve. I am a professional engineer and want to use your information to give building clients the options and disadvantages/advantages of the roofing type. Thank you. Rick

    1. Rick,

      Manufacturers conduct wind uplift (blowout) tests for their mechanically fastened and fully adhered membrane installations, and typically, by increasing the number of fasteners (reducing spacing) wind uplift rating goes up. Typically these test are conducted by independent labs. Then manufacturers post different fastening patterns required to achieve different uplift ratings.

      I live in Boston area, so typically we don’t deal with high winds, and thus I did not have much personal experience with damages dealt to the material from high winds.

      If real wind exceeds what roof is rated for, there may be damage – in some cases membrane may get torn out, have tears, etc.

      Obviously, wider materials will have lower wind uplift (compare 6′ wide roll vs 10′ wide roll).

      One solution that is relatively inexpensive, is to do BOTH: mechanically fastening all seams AND fully adhering membrane to the insulation.

      We don’t have “our” material – RoofCalc.org is independent informational resource, unaffiliated with any manufacturer. When I make recommendations, those are my own personal opinions based on my experience, and as you may see in comments – many roofing contractors and other industry folks don’t always agree with me. But as long as they respectfully state their opinions, we always publish such comments without censorship.

      Basically there is nothing to “reference” to your clients, besides my personal opinion.

      Cheers, Leo

  6. Leo,
    I have a covered deck I want to waterproof and place a floating deck over. It is 10′ off the ground with a finished ceiling below covering a stamped concrete patio. Since the material will be covered and not exposed to direct sunlight what would you recommend? I’m considering the peel and stick TPO do to its installation ease. Any Thoughts?

    1. Bill,

      TPO does not compare with galvanized large metal sheets.

      TPO is made for low slope / flat roofs. Metal is for steep(er) slope roofs. While TPO can be used on steep slope, I wouldn’t do it for multitude of reasons (mostly cosmetics / aesthetics / installation difficulties), metal SHOULD NOT be used on low slope & flat roofs. That is unless you want leaks and/or constant maintenance.

      And while structural metal panels ARE used on low slope steel buildings (warehouses, etc), the whole building is designed to work with those panels (from ridge to eave), and those panels are seamless. That is they run from roof edge to the ridge, without seams / splices. And in cases where there are seams, these roofs always leak!

      Here is an example:
      Structural metal panels roof leaks

      If you look at those staggered white spots – they are seams that were leaking, and I came to repair them.

      So, use proper material for the job.

      If you are concerned with TPO quality – go with PVC roof.

      Good luck.

  7. Mobile home in Florida had a large section ( 12 X 12 ) sink gathering water
    Going to repair truss sections and now consider a new roof. The old metal roof ( 1 foot sections clipped together ) is in bad shape. Many roofs in the park have TPO and the owners rave about the new roof but in most cases under 5 years old . Any suggestions as it is just a winter home and do not want to sink allot into it but want it to last 10+ years

  8. I have a commercial building with a flat roof in FL. We have gotten 2 different quotes and are unsure of which product to go with. Which product is the better choice? 60mil TPO or 60mil Duro Last.

    1. Nichole, I’d definitely go with Duro Last. I’ve worked on their 15-20 y.o. roofs, fixing holes made by snow/ice removal crew. Even after this mach time, the roof was very easy to repair, which speaks to the quality of their PVC.
      Also the Dura Last we worked on was 50 mil (or maybe even thinner), so 60 mil is definitely good.

      Good luck

  9. i have a new TPO residential roof. should a TPO roof be thoroughly washed and cleaned after installation? since day one i have had black streaks on my aluminum gutters and down the sides of the house. it won’t come off. is there a chemical residue left after installation: thanks for any info

    1. Marcia,

      TPO doesn’t need to be washed after installation.

      Black streaks on gutters are probably residue from tar/asphalt that was removed from the roof (my guess, that you had old tar roof) …

      Did these streaks appear BEFORE first rain (after install) or after? If after, then I’m confused …

      Please upload pictures to Imgur.com and post here.

      Leo