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TPO or PVC flat roofing ?? Which is best?

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kenl314

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Discussion starter · #1 ·
Hello- I am in some RE investment groups and one of our members had this question-
**************
TPO (Thermoplastic Membrane Roofing) COOL ROOF SYSTEM or Polyvinyl Chloride---
Does anyone within our REI group have any first hand knowledge of this material being used on their multifamily property?
If so, please give me your honest assesment on its merits. Is it worth it for a flat roof?
I have considered a couple of properties but with flat roofs, my underwrites are a bit sceptical.
Thank you in advance to whomever can provide me with some feedback on either this material or something similar that is beyond the traditional tar covering.
Sincerely,
John Gallion
****************

If anyone has any expertise in this, please PM me or post on this thread. I'll forward that right to this guy. Thanks,
Ken
 
#2 ·
I put pvc (durolast) on my apt complex flat roof and I regret it.
Its overpriced and proprietary. I'd go with epdm if I could do
it over again. Better yet ctp bur but thats another subject.

Who installed it is much more important.
 
#3 ·
I install all types of roofing but think PVC membrane is the best single ply on the market. TPO is still unproven, EPDM is good for a low budget but the seams and flashing reley on glues and tapes that can break down over time.
Some PVC like IB have colors available and offer a 25 year warrany on commercial and lifetime on residential. Dura Last , Sarnafil,Fibertite are all also very good but as with any roof its only as good as the crew that installs it. You may want to check out. http://www.youtube.com/watch?v=OcNuHrgujPQ or http://www.youtube.com/watch?v=qa0ezELeX64


RooferJim
www.jbennetteroofing.com
 
#4 ·
TPO is the Yugo of roofing materials. (it's cheap and you get what you pay for)
PVC is a proven membrane
Durolast has a less than stellar reputation in that market
Consider IB or Fibertite for a few
All roofs are only as good as the installer
 
#5 ·
I consider the PVC sheet made by Sarnafil to be one of the best available single ply membranes on the market. I base that opinion on the fact that they have been making their own sheet for a long time without changing the chemical formulation and that they have not had the membrane failure issues that have troubled so many in the industry.

TPO (and some early PVC's) has had some issues with membrane degradation/deterioration, especially out here in CA. The TPO mfg's say it was only in ponding areas, or where the sun reflected off a unit or a south facing wall and cooked the sheet or where the welder toasted the sheet along the walk pads or this or that. Bottom line is that they have had issues which caused their membrane to fall apart. If you can get them to talk about it they will tell you its all fixed now. Yep. Right. Uh-huh. :whistling

(FWIW, when TPO first started coming into the market it was touted as having the sheet stability of EPDM [ EPDM's + and PVC -] with the security of welded/fused seams of PVC systems [PVC+ and EPDM-])

However, in 2 weeks my firm is going to start installing a 2,000 square TPO roof because its the cheapest thing out there. I would rather install Sarnafil but the owner wants the cheapest roof with a 15-year warranty and Sarnafil cant come close on the price. However, the TPO will be lucky to last 15 years with the mfg. probably nursing it along the last couple of warranty years whereas the Sarnafil roof would be good for at least 20-25 years.

I dont think Sarnafil really likes residential work as their warranties are very limited for residences. Depending on the type of dwelling IB or Duro Last may provide better warranties.

As has been mentioned already, any roof is only as good as the installer. We recently replaced a 1 year old single ply roof originally installed by someone else due to continuing leaks caused by extremely poor workmanship. No membrane problems, just workmanship issues. You need to make sure that the roofer knows his stuff with the system that he is installing.
 
#6 ·
great info luv2roof - direct from the trenches.

was wondering if you could share some more details about the poor workmanship causing a leak after just a year on that single ply.
was it improper welds, fishmouthing, substrate issues etc.
 
#7 ·
The 1 yr. old mechanically attached single ply roof that we just replaced was supposedly done by a roofer doing his 1st single ply job. I didnt get the details as when we were on the job the owner, architect, GC, and lawyers and experts were all there watching so I wasnt in a question asking mood. (I took a bunch of pics with a new camera but lost them due to operator error:sad:)

The biggest problem contributing to the leaks were cold welds. You usually get cold welds when you use the wrong settings on a robotic welder. With a cold weld, the membrane seam will weld together and will visually look good but the seam will come apart when you test a sample of the seam. That is why you ALWAYS have to take destructive seam samples when using a robot welder. I didnt really see and voids or fishmouths but then I wasnt looking for them. By evidence of the mold and stains on the underlying insulation, there were quite a number of leaks.

Although probably not contributing to the leaks, one thing I had never seen before while removing the old roof was that we could rip the membrane along the seam. I have never really been able to "tear" a single ply membrane due to the reinforcing scrim. But in this case we could start at the end of a sheet and make a small cut (and many times didnt even make a cut) in the sheet right along the edge of the overlying sheet and then just rip the sheet up. The sheet would rip right along the edge over the entire length. It made me wonder about the overall intergity of the sheet. This may have been caused by the the robot welder cooking the sheet or something but I never did really figure it out.

There was a layer of Dens Deck and 2 layers of iso under the membrane. There were some larger gaps of about 3/4" in the top layer of Dens Deck and there were huge gaps (up to 12" in the bottom layer) in the iso. In fact, in one area they had used small chunks of iso as pedestals to support the 2nd layer of iso. They also installed the insulation plates in the literal corners of the Dens deck so that the plate would cover the corners of the 2 or 3 adjacent boards. It was a new fastening pattern that I had never seen ! These things didnt really contribute to the leaks but were indicative of a really crappy install job overall. It supposedly took the original roofer "weeks and weeks and weeks" to install the original roof while we got the thing done in 6 days with 8 guys. There was a heavy rain 2 days after we finished and there were no leaks in the system!:clap:

The original roofer has supposedly gone out of business (surprise!) leaving the GC holding the bag on this. I dont know why the roof system manufacturer didnt step up to the plate but its one I am not approved with and I dont know any details on that end. So I guess the lesson of the day, among others, is to use a reputable roofer installing a system that he is familiar with from a reputable manufacturer. It doesnt really matter if its a PVC or TPO sheet if the installer cant put it down right.
 
#8 ·
In my opion TPO is better then PVC, with that being said most pvc's around here are duralast roofs and they are real POS's, 5 years max. We have put on TPO and EPDM roofing for a very long time. We have had very good luck with EPDM and TPO. I am not talking about ballasted mechanically attached glued seam 45 mil EPDM either. Fully adherd EPDM with positive drainage (as with any roof). I have heard about the problems with TPO and sun reflecting off windows and such. My first choice would be BUR, you cant go wrong well unless you hire someone who doesnt know how to roof. Thats the big thing find a good contractor and stick with them, most of the time low bid will only get you sub par work and headaches down the road. With TPO and PVC you can sell them on the "green roof" idea. You can also get up to a 20 yr warranty with either system with most manufactures that we deal with. You can get a 30 with a 90 mil EPDM but you most people will not like the cost. Bur 20 or so years, but as long as you dont have people up their poking holes (think HVAC) you can get well over 20 with a properly installed system. Good luck just find a good experianced flat roofer and you should be fine.
 
#10 ·
1985GT - What specifically were the problems with the Duro Last membrane? Were they installation issues or membrane performance issues? Their membrane seems to be pretty good as I have not personally seen or heard of any problems. I dont care for their polymer term bars and fascia pieces and I dont really like how everything is a bit loose and baggy from prefabbing, but there membrane seems to hold up pretty well.

Debbie0 - No you cannot install a PVC membrane over EPDM without some type of separator. PVC is not suppose to touch EPDM as the EPDM is corrosive to the PVC.
 
#11 ·
Debbie0 said:
Can I still put PCV on EPDM after EPDM is no longer working? OR I should first remove EPDM and only then install a PCV roof coating..
Click to expand...
Depends, here you can have only a total of 2 roofs. So if the EPDM was a recover over a BUR then no. If there is nothing under the EPDM aside from insulation, then yes. You will have to seperate the layers IE cover board or more ISO/insulation. In our experiance we have noticed that TPO and PVC will condinsate with the big temp swings. So a cover board may not be a great thing to use as fiber board will be come a big pile of mush. Maybe use a dens deck.
 
#13 ·
Luv2Roof said:
1985GT - What specifically were the problems with the Duro Last membrane? Were they installation issues or membrane performance issues? Their membrane seems to be pretty good as I have not personally seen or heard of any problems. I dont care for their polymer term bars and fascia pieces and I dont really like how everything is a bit loose and baggy from prefabbing, but there membrane seems to hold up pretty well.

Debbie0 - No you cannot install a PVC membrane over EPDM without some type of separator. PVC is not suppose to touch EPDM as the EPDM is corrosive to the PVC.
Click to expand...
Installation issues with duralast are almost a given in our area as only a few companies will install them. We have also seen the PVC shatter with hail and cold temps. I belive this is more because of the thickness of the PVC and age. I think duralast atleast the ones we have seen are 32 mill. I do not know if they offer a thicker sheet or not. I would venture that PCV that thicker would hold up better. Plus I think think they look very poor. Using field sheet to wrap a soil stack and just bunching up corners on a wall look piss poor IMHO. Show a real lack of pride in one's work and it goes to show that cheap is not good.

Now I only have seen duralast roofs here in nebraska/iowa area, I have no idea if in other areas they are installed better and or hold up better. Just wanted to say that before someone takes it the wrong way.
 
#19 ·
1985gt said:
Installation issues with duralast are almost a given in our area as only a few companies will install them. We have also seen the PVC shatter with hail and cold temps. I belive this is more because of the thickness of the PVC and age. I think duralast atleast the ones we have seen are 32 mill. I do not know if they offer a thicker sheet or not. I would venture that PCV that thicker would hold up better. Plus I think think they look very poor. Using field sheet to wrap a soil stack and just bunching up corners on a wall look piss poor IMHO. Show a real lack of pride in one's work and it goes to show that cheap is not good.

Now I only have seen duralast roofs here in nebraska/iowa area, I have no idea if in other areas they are installed better and or hold up better. Just wanted to say that before someone takes it the wrong way.
Click to expand...
I have only seen the duralast roof here in Pa and I agree with you:rolleyes:
 
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#20 ·
Thermoplastic polyolefin, or TPO, is the fastest-growing segment of the commercial and industrial roofing industries. Fueling this growth is the increased use of TPO in southern climates, where reflective, energy-efficient and cool roof products are becoming the norm.

Polyvinyl Chloride (PVC) is a trusted membrane that has been performing admirably for decades in the European market and in North America. PVC also offers excellent resistance to rooftop chemicals, including acids, oils and greases.

Typically PVC would be installed at restaurants, industrial applications, etc. There really doesn't seem to be a reason for you to incur the additional cost with the application you have described. Therefore, we would recommend a TPO membrane.

There are many different manufacturers of TPO and each one has different quality control procedures and requirements for contractors to become "authorized applicators". We would recommend Carlisle. They offer warranties ranging from 15-30 yrs. Many of which are NDL (no dollar limit), total system warranties.

Whitco Roofing, Inc.
 
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