EMT through the eve

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Green Building Solutions
Green Building Solutions Registered Users Posts: 24 ✭
in Advanced Solar Electric Technical Forum #1
When you poke EMT down through the eve of a roof how do you seal it so no water leaks in?

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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
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    Re: EMT through the eve

    conventional plumbing type roof flashing of the proper size,,, either all rubber/plastic or metal/lead with rubber insert stretched over the pipe,, just as if you were doing an overhead service entrance through the roof,, or a pluming vent. http://www.grainger.com/Grainger/items/1VNH5

    Available in many sizes and materials, for shingles, shakes,, torch down or standing seam roofing material.

    Tony
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  • lorelec
    lorelec Solar Expert Posts: 200 ✭✭
    #3
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    Re: EMT through the eve

    Check this site out if you need the flexible silicone flashings. They have a huge selection and really low prices. I've used them before and the quality of the products is excellent. www.bestmaterials.com

    Marc
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #4
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    Re: EMT through the eve
    Green Building Solutions wrote: »
    When you poke EMT down through the eve of a roof how do you seal it so no water leaks in?

    Thanks

    For asphalt shingled roofs, I normally just use a standard pipe flashing and the dreaded black goop.

    http://www.bestmaterials.com/galvanized-roof-pipe-flashing-638.html

    Buy a flashing with a smaller hole than you need, then use snips to open it up to the right size so it's a tight fit. Also keep in mind that on a sloped roof, the hole in the flashing will NOT be circular - it will need to be elongated to properly fit the pipe when the flashing is at an angle.

    Slip the top edge of the flashing up under the upstream shingles, secure with a couple of screws that are long enough to hit the wood under the shingles, then slop on the goop.

    http://www.roofingcontractor.com/Articles/Products/15b74d91eb98a010VgnVCM100000f932a8c0____
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #5
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    Re: EMT through the eve

    One should never rely on black goop to weather seal in the long run,, it will only lead to heartache eventually. Proper flashing, properly installed should require no tar,, and should last the life of the roof. Some of the EPDM and lead flashings can be cut tight to fit any pipe diameter.


    Tony
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
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    Re: EMT through the eve

    i agree with you on the black goop tony as that tends to shrink and crack from what i've seen in my past experiences.
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #7
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    Re: EMT through the eve

    I disagree (obviously).

    I've seen those flashings with the rubber center crack and leak more often than the goop. And once they leak - they'll get gooped anyway. A lead flashing, where it meets the pipe, is not going to magically stop water - you still have to seal the joint.

    As for the goop shrinking and cracking...I've never seen that with Henry's. Straight tar - yes it does dry and crack, but the plasticized stuff doesn't have that problem. I've seen jobs that I did 10 or 15 years before that were still nice and waterproof - and the goop was still not completely "hardened".


    Also; to say, "a properly flashed roof will not leak" - well, that's nice in theory, and is certainly true when talking about ridges and valleys and edges (though even they are often gooped)...but the reality is that anywhere a roof is penetrated it will need to be sealed with *something* - and the proper sealant IS the dreaded black goop.

    Even if you use a flashing with a rubber center, or a lead flashing, you still have to attach it - either nail or screw it down - and you *have* to goop over the nail or screw heads and around the edge of the flashing just to be sure you won't get a leak at that point.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #8
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    Re: EMT through the eve
    dwh wrote: »
    I disagree (obviously).

    I've seen those flashings with the rubber center crack and leak more often than the goop. And once they leak - they'll get gooped anyway.

    Just did the goop thing on my vent, as the rubble dry rotted and was leaking.

    The most important thing I see is, the EMT must move with the roof decking as is moves due to temperature/wind/snow loads. If it is rigid, no matter what is used, it will leak.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #9
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    Re: EMT through the eve

    If I ever had to put a hole in a roof I would use what marine installers and really good roofers use. Sikaflex is even sold by Solar Depot the western US's largest warehouse of equipment. Walking thru their warehouse is just plain eyecandy!

    I wish I could give a good report for the plasticized Henry. It is good in a wet emergency but out west it cracks in one or two years even with fiberglass tape.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • solartek
    solartek Solar Expert Posts: 69 ✭✭✭✭
    #10
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    Re: EMT through the eve
    Dave Sparks wrote: »
    If I ever had to put a hole in a roof I would use what marine installers and really good roofers use. Sikaflex is even sold by Solar Depot the western US's largest warehouse of equipment. Walking thru their warehouse is just plain eyecandy!

    I wish I could give a good report for the plasticized Henry. It is good in a wet emergency but out west it cracks in one or two years even with fiberglass tape.

    Since I don't use Solar Depot as a distributor I'm curious which version of Sikaflex they are selling. It was very popular to use Sikaflex-1a for sealing roof penetrations or caulking around flashing but most people ignored the manufacturer's known exclusion for use with asphalt shingles. See the last limitation in the data sheet for Sikaflex-1a found here.. A better choice for roof penetration on an asphalt shingle roof is a tri-polymer sealant like Geocell 2300 (which is what I use.)
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #11
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    Re: EMT through the eve
    Dave Sparks wrote: »
    II wish I could give a good report for the plasticized Henry. It is good in a wet emergency but out west it cracks in one or two years even with fiberglass tape.

    Well, I'm "out west" (Los Angeles) and I've never seen that happen.

    I've personally done about 70 service upgrades - at least half of which were overhead drops with risers through the roof and asphalt shingles. I've been back on quite a few of those roofs years later and have not even *once* seen them dried out, cracked or leaking. Nor have I ever had to use fiberglass tape.

    I have seen plenty of dried out, cracked and leaking joints, including joints with fiberglass tape on them - but those were done with hot tar, not plastic cement (and not done by me).


    I wondered why you mentioned "wet" and then I noticed that in my OP I linked to Henry's #208, when I normally use #204. Perhaps that's the source of a misunderstanding?

    Though I will say that I have also used #208 when I couldn't get #204, and never had a problem with it either.

    I will note that both comply with ATSM D4586-07 (asphalt roof cement), except 208 will run easier under high temperature.

    Sikaflex-1a complies with a different standard, ATSM C920-08 (general purpose elastometric sealant).

    I've never used Sikaflex, but it looks like a pretty good goop for a lot of things.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #12
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    Re: EMT through the eve

    If you use the good epdm ones they will out last the life of the roof in most cases, I would never trust tar for the long term unless I was prepared to re-tar it every year or two.

    Tony
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