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Long term durability of gasket + sealant solar PV mount flashing

Patrick OSullivan | Posted in General Questions on

I am hoping to initiate a PV project soon and am working through quotes with a couple reputable installers.

One wants to use UniRac FlashLoc (https://unirac.com/wp-content/uploads/pdf/Flashloc_Brochure_20190904_Web.pdf) mounts. It’s certainly a very installer friendly product. A single lag holds it against a shingle. The lag compresses an EPDM gasket onto the shingle, and then the whole thing is filled with a sealant until it overflows.

But I do worry about the long term durability vs a more traditional metal flashing integrated mount.

My roof is brand new asphalt shingles, underlayment, and fully taped Zip sheathing. I am installing closed cell spray foam to the underside of the roof deck as this was the most practical retrofit for this 100+ year old house, hence why I want to be very sure that I minimize the chance of leaks.

Does the FlashLoc product seem reasonable to trust or would you run the other way? Part of me seems skeptical and the other part of me likens this to through fastened metal roofing where you are relying on a gasket to prevent a leak. I know Martin has commented favorably on modern through fastened roofs and the  gaskets used.

Replies

  1. Expert Member
    Akos | | #1

    The reason to use this is to save on installation costs. The question comes down to how much difference that is for the overall solar panel install, I would guess it is not that much.

    I would rather go with something that doesn't need quality install to keep water out and something that can be re-used if the roof needs to be re-shingled down the road.

  2. Expert Member
    Zephyr7 | | #2

    The top filled part sounds like a pitch pot, which has been used forever. The gasket though sounds like a failure point to me. I would be more comfortable with conventionally flashed structural supports. Sealants can fail, especially when they’re between two things that will expand and contract at different rates in the sun. Flashing relies on gravity to work, and gravity is generally pretty reliable over the long term :-)

    Bill

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