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  1. #1
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    Default What Kind of Roof Covering is This?

    Saw this on a rowhome in South Philly today and it's new to me. The roof covering looked alomost like a canvas/tarp membrane. It have quite a few loose and buckled sections that were wrinkled and not laying flat on the roof.

    1 - What type of roof covering is this?
    2 - What is the proper method of installation? I can't believe that the wrinkles and loose areas are OK.

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  2. #2
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    Default Re: What Kind of Roof Covering is This?

    Nick, that looks like PVC membrane that has been used around here for several years. What I have seen is smooth plastic and bright white that is loose fit.
    I understand it has to be separated from standard tar roofing products because it is not compatible.
    Typically the ballast rock is removed and insulation board is screwed into place and the membrane is placed with vents similar to your picture.
    Your picture shows some definite problems with poor installation at exterior walls, flashing details, and all that hot mopped tar on the edge.
    I think the main selling point is the white reflective surface conserves energy in the A/C climates and long warranty.

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  3. #3
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    Default Re: What Kind of Roof Covering is This?

    BTW, some of the PVC materials are rated by the manufacturer for prolonged exposure to ponded water like that shown in the third picture. I don't like to see it, but a commercial roofer I trust (this stuff has been around longer in commercial than residential use) tells me that in his experience it's OK as long as the ponding is not a weight issue.


  4. #4
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    Default Re: What Kind of Roof Covering is This?

    To my knowledge, PVC is not rated or allowed to have ponding water.

    Some ('some') EPDM roofs are rated for that.

    I inspected a house (4 houses before he finally bought one) for the man who worked with (I think it was Carlyle) which made EPDM sheets for rice paddy farms and the like. The workers would unfold, then unroll (kind of like rolling carpet up where you roll it up then fold it), the super large sheets of EPDM sheets on the ground within a shallow earthen dike area, lift it and let the wind straighten it out, laying it back down fairly straight and smooth, then laying it up and over the earthen dike they had built.

    Fill it partially with some dirt and flood it - instant rice paddy.

    When the Dallas-Fort Worth Airport was being designed, he suggested using that material, it had proven to be water tight for years in those instant rice paddies and other farms like that, over the large skeleton roof system. They made one minor change, though, instead of making the material thin like they did for the rice paddies, they made the material think, somewhere about 1/2" thick.

    Worked well for that use. That was the first EPDM roof.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
    Tim Moreira's Avatar
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    Default Re: What Kind of Roof Covering is This?

    Nick,

    At the hospital I work at at night, we have this kind of roof on about 25% of our roofs. They have held up better than I thought.

    When I first saw then, I thought "what is this stuff" but after 4 years of (me) being there, they are the only roofs that really have yet to have leaks.

    No idea how long they have been there or how long they are supposed to last. Works great unless it gets a rip or puncture. Of course, so does most stuff.


  6. #6
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    Default Re: What Kind of Roof Covering is This?

    It looks just like a Duro-Last roof. You should have found a "iron on" with care instructions somewhere on the roof. See photo 4 below.

    Commercial Roofing System Single-ply membrane roofing system - Duro-Last Roofing, Inc.

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  7. #7
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    Default Re: What Kind of Roof Covering is This?

    Interesting. Thanks for the responses guys. I did find one small pucture hole in the roof membrane. Aside from that, it sounds like the other conditions I saw were normal for this type of roof. The buyers told me the roof is 5 years into its 10 year warranty so they should be able to get the puncture repaired without a problem.


  8. #8
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    Default Re: What Kind of Roof Covering is This?

    The problem with those roofs though, is that during hurricanes and other high wind events, the fact that there is no total adhesion of the membrane but point anchorage (and usually not enough of them), and the fact that PVC stretches, those roofs will be lifted like big balloons and be stretched out of shape (should they not be sucked right off the roof).

    After some of the hurricanes down in South Florida, you would see many of those laying over the edge of the roof parapet wall and hanging down the side of the building. The had been lifted up and off their fasteners (too few and not properly inserted) and then the wind just flopped them over like a big sheet, hanging them out to dry down the side of the building. Of course, the apartments and condos inside were destroyed by the wind and rain too.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  9. #9
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    Default Re: What Kind of Roof Covering is This?

    Jerry,

    The Sarnafil PVC membrane is the one I'm aware of where ponding is not an exclusion.

    "Sika Sarnafil’s specially formulated thermoplastic membrane is also designed to withstand the everyday occurrences of ponding water and other natural elements such as birds, biological organisms, pollution, wind, hail and snow."

    PVC Roofing - Thermoplastic Advantage -Sika Sarnafil


  10. #10
    Join Date
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    Default Re: What Kind of Roof Covering is This?

    Michael,

    "Vinyl roof membranes also stand up exceptionally well to ponded rainwater, which often remains despite efforts for positive drainage, and to a variety of typical rooftop contaminants, such as air pollution, bird droppings, acid rain., etc."

    From the link on their site.

    That means, 'from the typical ponding of water which accumulates as a result of poor drainage', not from 'the almost intentional inches-deep and stays-there-all-the-time ponding water shown in that photo.

    At least that what several of the manufacturers told me years ago "Yeah, our roof can deal with ponding water from poor drainage which dries out after a day or two, but don't try to make a pool liner out of it on the roof'.


    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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