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

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

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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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