Installation Tips and Guidelines for roofers from TPO manufacturers

If you are roofing contractor already installing TPO membranes or considering starting to work with TPO there are some important installation intricacies that you need to be aware of to get your job done well. TPO roofing membranes are becoming increasingly popular both in residential and commercial single ply roofing markets across the US, offering an economical price as compared to its rival PVC roofing membranes.

TPO roofing membrane offers many benefits similar to PVC roofing, in the last couple of years, the membranes have been noted to age and deteriorate prematurely under conditions of high solar and heat loading. This issue has been particularly prominent in the Southern states, that get both a lot of sun and heat year round.


Estimated 1500 s.f. Flat Roof Costs in US Average Flat Roof Costs in US
Rubber Roof
Rubber
$7065
TPO Roof
TPO
$7455
PVC Roof
PVC
$8055

See costs in your area Start Here - Enter Your Zip Code



While manufacturers are working on improving the membrane’s formulation to address this issue and revised ASTM standards for TPO are also in the works, manufacturers also believe that proper installation is key for a TPO membrane’s longevity and durability under these extreme conditions. During MRCA’s 61st Annual Conference, held in October 2010, a panel of representatives from various TPO manufacturers discussed TPO’s Long-term performance and offered important guidelines to roofing contractors on proper TPO installation techniques.

The TPO panel included representatives from GAF Materials Corp, Carlisle SynTec and other commercial roofing manufacturers. The panelists made it a point that improper installation practices can go unnoticed during installation itself but can lead to major problems as severe as roof failures years down the line. Hot-air welding of the seams was identified as the practice where most significant mistakes were being made by contractors. They provided the following tips and guidelines for properly installing TPO membranes.



1. Test welds should be done at least twice daily — at the start of the day and after lunch. Also, it is really important to do test welds whenever the machine is restarted. This is a necessary step that can prevent excessive heat during welding. Excessive heat has been identified as a major problem that needs to be safeguarded against because it can consume polymer stabilizers that will lead to the membrane’s deterioration. Excess heat can result from the air temperature being too high as well as the welder speed being too low. Ideal welding temperature should be the lowest temperature that provides good seams at production speeds.

2. For proper installation, there should be no welder drag. A contractor needs to align the inside edge of the nozzle with the edge of the roller. If this is not done correctly, improper alignment of the hot-air nozzle can create gouges in the membrane outside of the seam.

3. It is important to be careful when probing seams, because incorrect probing or lack of care can also lead to problems down the line. When probing, it is best to use a blunt probe. Probes tend to sharpen with use and as a result must be occasionally dulled.



4. To avoid future problems, it is also critical not to crease the membrane when it is folded during installation. Folding over the membrane can result in a hard crease and surface cracking. To avoid this, it is best to fold back the membrane for applying adhesives or fasteners. However, it is important not to place any weight on the fold to hold it in place.

Recommended TPO reading:

Pros and Cons of TPO Roofing material

TPO Roof Heat Welding Video


Estimated 1500 s.f. Flat Roof Costs in US Average Flat Roof Costs in US
Rubber Roof
Rubber
$7065
TPO Roof
TPO
$7455
PVC Roof
PVC
$8055

See costs in your area Start Here - Enter Your Zip Code




Published date: August 21, 2012

37 thoughts on “Installation Tips and Guidelines for roofers from TPO manufacturers

  1. Flo Baldwin

    Good morning TPO experts! Is it possible to use a steel drip edge over the TPO? The termination bars dont have a nice look to a residential installation. The drip edge would have to be affixed to the roof by puncturing through the TPO. Can a strip of TPO be welded or adhesive bonded on top of the screws holding the drip edge down to seal the top surface of the roof? This is the only issue holding me back from a TPO installation. Thanks very much for your help.

    Reply
    1. TPO Roofer Post author

      Flo,

      Most common is to use Aluminum drip edge in exactly the manner you describe, but steel can also be used.

      Most commercial projects don’t use termination bar. Same with residential, where aesthetics matter.

      With TPO the only way is to GLUE a strip of TPO to cover screw holes. With PVC, there is steel drip edge with PVC cladding, so you can actually weld to it. There is no TPO clad edge metal that I know of. Welding is better, but gluing also works.

      I hope this helps.

      Reply
      1. Flo Baldwin

        Thank you very much for the useful information. Just one more question … To my understanding, the TPO layer hangs over the side of the facia board and then the drip edge goes over the TPO layer. How much overhang should the TPO layer have over the side of the facia board? And how is the TPO layer attached to the side of the facia board? I know that screws will be used on the top of the roof to hold the drip edge on the top of the TPO layer, but I would also like to know how the TPO is attached to the side of the facia boards. Thanks again. Flo?

        Reply
    1. TPO Roofer Post author

      Hi Lisa,

      I have data for only one company that does TPO in NM – they are in Las Cruses.

      They charge roughly $5.75 per sq. ft. with one layer rear-off, and basic insulation. A 1500 s.f. roof with them would be roughly $8700

      Hope this helps

      Reply
    1. TPO Roofer Post author

      Yes definitely. In fact, my 2005 RV has a factory TPO roof 🙂 some no-name company

      It would actually be fairly simple to do – the only issues would be antennas / AC roof-top units. Other protrusions can be removed completely.

      You plan to do it yourself, or hire someone?

      Regardless of who will do it – use SolarSeal 900 sealant… not that garbage that’s sold in all RV/Camper stores/websites.

      Reply
  2. Kathryn Hoch

    Hi I live in VA and have a flat residential roof of TPO installed in 2013. After our wind storm – tree falling on the house, we need to repair or replace the roof, mostly due to 10-12 puncture from the brances. These holes are 2 inches across or less. My roofer says that they will repair as many as four punctures but after that the integrity of the roof is at stake and we should replace the entire roof.
    Also, if we replace are there any weather/temprature guidelines our roofer should be following regarding the installation (too hot, too cold)? Thanks

    Reply
    1. TPO Roofer Post author

      Kathryn,

      Your roofer is trying to get an easy job out of you – this integrity thing is a bunch of “bull”. You can repair as many holes as you need / want, and it should not affect your roof performance or integrity… (assuming patches are welded in correctly, surface properly cleaned before patching, etc). Now one caveat – i don’t know what TPO you have, so 5 years on the roof, may have affected “weldability” … meaning patches may not weld well.

      Now if your insurance would cover replacement (which I highly doubt, because it’s just punctures and they are easily repairable) … i would just take the money and still only do repair… it would really be a waste to trash a fairly new roof over few holes…

      I would never work with this contractor though … because they are not honest with you. I don’t suppose your roof is still under labor warranty – so it doesn’t make a difference whether this or another roofer does the repair – as long as repair work is done well!

      Good luck

      Reply
  3. Mike Waller

    Hi there. We have a newly framed flat roof deck over a garage (about 266ft and the slope runs 1/4 in every foot) and was considering TPO membrane to waterproof it. However, we want to put interlocking composite decking on top but underneath the decking we’re looking at appears to be hard plastic and not rubber. Wouldn’t that rip or cause tearing in the TPO membrane? And if doing so, would that void the warranty on the membrane? Also, what about water drainage under the decking? Is that recommended?

    Reply
    1. TPO Roofer Post author

      Mike,

      To prevent tears, use a strips of material under decking. Since you have roof slope, I assume decking will run perpendicular to slope. Run membrane strips 12-16″ on center down the slope (perpendicular to decking). Something like this:
      TPO flat roof deck

      This will create separation between deck and roof, and provide space for water runoff. You may want to have at least 1/8″ thick strips – can double up your material.

      As far as warranty, you need to clear this with manufacturer that you will use.

      Good luck

      Reply
  4. Neil Button

    I just got my independent contractors liscense and have been installing tpo and PVC rubber roofs and was searching the net for more information on these products as it seems not a lot of people are too familiar with them or know much about it,so any info is truly appreciated thankyou

    Reply
  5. Alex Casas

    I recently had my roof done and I went from standard roof to a to type The contractor who installed it did not replace the rotted plywood nor did he use any type of insulation. When I asked them they stated that the manufacture did not require on this type of too installation. Is there any too roof that does not require on a flat roof. May I add that they laid it over existing 3/4plywood only

    Reply
    1. TPO Roofer Post author

      Alex,

      You have to look at your particular product installation specs, but generally, TPO should not be laid directly over substrate. Some sort of separation is needed. Mainly because fasteners that hold down plywood, can back out and make wholes in the roof.

      Now not changing rotted plywood is direct violation of ANY manufacturers’ installation specs, because substrate must always be solid and in good condition. I belive this also violates local building codes (consult with your building inspector).

      Is your contractor licensed by manufacturer? If so, I believe, they should be canned from approved contractors list AND manufacturer should take care of your roof.

      Who is the manufacture of your TPO membrane?

      Good luck

      Reply
      1. Alex casas

        Restore masters. Its goin on almost a year im having to deal with these guys. I wish they would. I have a good case againts them for not doing a proper installation and causing more damage to my home from all the roof leaks. also for not pulling permits. Then tried giving me a fake one. Not calling in an inspector saying that ot wasnt required. Then they sub out two more contractors to only fix the leaks. Yhat backfired on them when both contractors told them what a shitty job they had done and al the violations. Both contractors denied doing the work for restore masters. Then they gave me different installation guide lines from various tpo products which wasnt even the brand they used. I also got ahome inspector to submit a report , which stated all violations. It even got to the ceo of their company and he lied about making things right. I threatened them with a lawsuit. So they recently decided to refund my first payment and dont want to redo my roof or pay for all of the damages from their roof installation. I got all the proof in emails and the contractors and inspector willing to testify. Please help .

        Reply
      2. Alex casas

        I really dont know who the manufacturer is. As i stated in my last response, they tried giving me three different installation guides from three different manufactures. They thought they could pull a fast one on me after I caught them in all their lies and unethical working practices. They should pay for their lack of good judgement.

        Reply
  6. Richard

    I am Richard, I am doing a flat roof,I want to use a bitchathain under payment over OSB then put the TPO over that, thinking about the best installation I could provide, the customer counting costs does not want to use the butilain, I don’t agree do too integrity reasons, what do you as contractors?

    Reply
    1. TPO Roofer Post author

      Dan L,

      No you cannot walk on it every day.

      1st – you will void your warranty.
      2nd – its very slippery when wet.
      3rd – you will damage it very fast.

      There are special walk threads made for TPO / PVC that weld / glue to the roof, and you can walk on them all the time.

      Good luck

      Reply
  7. Mark

    I have a very shallow pitch tar and gravel roof. One contractor is proposing to install 1″ to 1 1/2″ insulation on top of existing roof screwing it down with plates and then lay TPO membrane on top. Can TPO be installed this way?

    Reply
    1. TPO Roofer Post author

      Hi Mark,

      Yes TPO can be installed that way. That insulation is referred to as ‘1/8″ tapered’ … I recommend 1/4″ tapered that would ab a 1.5″ to 1/2″ four by four feet board. I also don’t recommend installing it OVER existing roof, unless you know there are no leaks and substrate is dry.

      Depending on roof size, your highest point (insulation thickness) can be few inches, because the 1″ to 1/2″ is just one section of 4×4′.

      Good luck

      Reply
  8. Brad

    Hi there, just wondering if you can tell me if it is common practice to place a second layer of TPO over the first, covering about 1000 square feet. Will this cause moisture or condensation between the layers with no where to go under it.

    Reply
    1. Leo - Roofer

      Brad, this is totally not standard, and should not be done. You are trapping moisture and creating tons of issues doing this.

      Removing TPO is super easy (and thus INEXPENSIVE), and you can even reuse the insulation …. even the plates / seams can be left in place, to reduce removal labor… but main sheets need to be cut.

      Good luck, Leo

      Reply
    1. TPO Roofer Post author

      John,

      Yes, we’ve done it once, per request of the building owner – but I recommend dedicated slip sheet … it’s actually not any more expensive, and house wrap can act as a moisture barrier, and affect condensation under PVC membrane.

      Reply
  9. Paul Eytcheson advanced guttering plus

    checking a roof for customer and ive been doing a few pvc roofs for a couple years now and i thought it was pvc but ended up being tpo the customer said antways i tried to weld a sample piece and would not adhere? are they not compatable products to weld together? iv e never used tpo and thats why im asking any help would be greatly appreciated

    Reply
    1. TPO Roofer Post author

      Hey Paul,

      Quick answer – TPO and PVC are NOT compatible and will not weld together. It is strange because the welding process is the same, and you would think that since you melt two thermoplastics, when they are squeezed together they would bond. But no … they will not.

      So my recommendation – either buy some scrap roll of TPO from a roofing supplier so you could weld patches, or find a local roofer that installs TPO and buy as scrap piece from them. I don’t think that you will need more than 50 square feet of membrane for patches and repairs. Might also buy some unreinforced patch material for corners, pipes, ets. Don’t uses field membrane for patching penetrations.

      But … i should not teach you this – you’ve installed PVC before and know the process.

      Best of luck – let me know how you made out.

      Cheers, Leo.

      Reply
  10. ART MILLER

    I WOUD LIKE TO APPLY A FULLY ADHERED TPO OVER AN EPDM EXISTING ROOF.
    THE INSULATION UNDER THE EPDM IS EXCELLENT AND I SEE NO REASON TO APPLY A 1/2″ ISO BOARD FOR THIS PROJECT.
    IS IT POSSIBLE TO INSTALL IN THIS MANNER?

    Reply
    1. TPO Roofer Post author

      Art, you can do it, but ONLY if you remove epdm rubber roof first. You can then glue new TPO to the existing insulation.

      You cannot glue TPO to EPDM.

      Note – when you remove rubber, it may tear the parts of top fiberglass (or fiber) insulation, and there will be a lot of dust – so you should clean surface thoroughly before adhering the TPO membrane.

      Optionally, you can slice the rubber (make many cuts to allow moisture to pass through) and then screw in 1/2″ OF FIBER INSULATION, and glue TPO on top. I know this is what you want to avoid – but it’s either removing EPDM completely or screwing in 1/2″ fiber.

      3rd option is to slice rubber, install separation sheet, and Mechanically Attach TPO.

      Best of luck – let me know how you did.

      Leo

      Reply
  11. matt

    Do you have to use the adhesive to stick the new tpo to the insulation boards? I just looked at one that was not glued down. Looks a little waivy..

    Reply
    1. TPO Roofer Post author

      Matt,

      You can use either adhesive or a mechanically attached assembly. Both are approved methods of installation. If you never see the roof, it does not matter much, which one you chose, unless there is some technical requirement for either method.

      If you do see the roof a lot, then a fully adhered (glued) method is prefered as you most avoid imperfections.

      A little wavy is normal in mechanically attached roof, as it’s virtually impossible to have a 1000 sq. ft. sheet to lay flat after you put 100s of screws and plates in it 🙂

      I hope this answers your question

      Reply
  12. Brandon Brock

    Hello I have a roofing business in bowling green ky. Do you have any kind of literature to make giving estimates or proposals for installing a tpo roof system easier or coming up with square foot prices for material and labor . Perhaps you have guides for measuring, what to look for to figure out what tpo membrane is recommended and the flashing and accessories needed. Last thing and I apologize for all the request but can you send or email price lists for tpo membrane and accessories

    Reply
    1. TPO Roofer Post author

      Brandon,

      You need to partner with a manufacturer and they will provide most if not all the information you are looking for.

      Contact a salesman for the MFG of your choice and see if you can become approved contractor

      Reply
  13. Ruth

    Nice blog post! I am a roofer (it may sound strange) and I like the fact that people are giving so useful advises.

    Reply

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