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which sealant for roof flashing...

Post in 'DIY and General non-hearth advice' started by Dogbyte, Dec 12, 2013.

  1. Dogbyte

    Dogbyte New Member

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    ive read a lot of opinions. i know i could probably go with a 100% silicone sealant for the storm collar , but im not sure about under the flashing, and also the shingles where i will need to pop the tar strip apart and reseal. they do make 100% silicone black, which has a high heat resistance, but i didnt know if there was one type of sealant that i could use for it all that would be clear.

    i know for sure i want to use a clear sealant, and if i could use something more permanent under the flashing in stead of the 3-4 year range of 100% silicone, that'd be want i want. is there something between 100% silicone and tar i guess is what im asking.

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  2. Highbeam

    Highbeam Minister of Fire

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    You shouldn't need any sealant on the roof jack. No exposed nails and no sealant. If you feel like you defeated the standard issue tar strip that comes on the shingles that keeps them from blowing up then you can either wait until the heat of next summer for them to reseal naturally or you could dab some Henrys roof sealant from a caulking tube in just those spots. Think nickel sized dabs under the shingles.
  3. MDFisherman

    MDFisherman Member

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    Check into ice and water shield. It is thicker than tar paper and has a sticky side to it. It comes and a roll and you can stick it over plywood or sheetmetal. My experience with caulk and roofing cement is that they all fail over time.
  4. webby3650

    webby3650 Master of Fire

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    We aren't talking about an entire tear-off and re-roof here!
    Use Silicone on the storm collar, I prefer silver personally. I will seal under the tabs after I lift them with a very small dab of roofing cement, and then I fill the small gap between the shingles and flashing boot with the same cement in a caulking tube. The only reason is to prevent debris from being trapped in this area.
    Hogwildz likes this.
  5. MDFisherman

    MDFisherman Member

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    I'm not talking about a full blown roof tear off. You use it in the critical areas where ice can dam up and where shingles will blow up and let wind driven rain in. It also seals the nail holes.

    You can use all the silicone you want. If I am making a new roof penetration I put ice and water shield down.




    http://www.na.graceconstruction.com/underlayments/download/GIWS-060V-GIWS.pdf
  6. webby3650

    webby3650 Master of Fire

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    I'm very familiar with the product, thanks for sharing.
  7. Dogbyte

    Dogbyte New Member

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    ok, well, i guess ive sat in on a few DIY'ers that did it a little different.

    no sealant on the roof? not even where the flashing sits over top of the downhill shingles? and no sealant for the fasteners on the downward side of the flashing? I'd be nervous not making it where water cant blow up under the shingles you gotta lift up especially around the edges of the flashing, also that little gap between each layer of shingles, where it steps down, the flashing sits on top of that and you have a gap underneath that i'd be afraid water could eventually work its way in. i have architect shingles too, so those little gaps will be more often i would think.

    if no exposed fasteners, then i assume you only fasten on the left/right/upward sides only?
  8. webby3650

    webby3650 Master of Fire

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    If the flashing doesn't sit down tight against the shingles I will use a few on the tail of the flashing. Then put some of the Silver Silicone over the heads. The Silicone we use has a 50 year warranty. You mentioned 3-4 year life? I see 20 year old Silicone all the time that has to be cut off of the flashing.
  9. Dogbyte

    Dogbyte New Member

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    well i didnt necessarily mean its gotta be replaced in 3-4 years, but thats how long i check all my insulated windows, and exterior doors around the trim... its 100% silicone. I may not be the best at caulking, but ive never had any that lasted 20 years here. i just try to keep them checked very 3 or 4 years in case they start to crack and fail.
  10. webby3650

    webby3650 Master of Fire

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    Just make sure to tool the caulking. The biggest reason sealant fails is because many people just pump it on and never touch it.
  11. Dogbyte

    Dogbyte New Member

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    Are you calling the tail of the flashing, the downward side?
  12. Highbeam

    Highbeam Minister of Fire

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    Correct, no sealant/cement on the roof. The last thing you want to do is seal up the tail of the flashing, that's where water needs to get out. You only nail the flashing on the top corners and the sides. If you didn't buy a smashed roof flashing then it will lay flat on the tail and one nail near each corner is plenty. No exposed nails that you have to depend on goop to seal.

    I have another pet peave, its the joint between the shingles and the cone. I insist on a 3/4" to 1" gap all around for water to travel and for debris to flow away from the cone. That cone/shingle interface is the most common leak point since some roofers like to try and make this gap zero by shoving the cone into the shingles.

    Get good at installing roof flashings. The same priniciples apply to every plumbing boot, and other device up there. Good roofers only use the goop at the last shingle on a roofing job and the storm collar.
    MDFisherman likes this.
  13. Dogbyte

    Dogbyte New Member

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    Ok i believe i understand now. about the shingle/cone area of the install...do you trim back the shingles from the hole you previously cut, so you keep your center bearing for the pipe to go through? Can you explain to me what is happening when a leak begins at this place when debris builds up? is it freezing or clogging up to the point where its reaching the hidden fasteners on the top side of the flashing?
  14. Highbeam

    Highbeam Minister of Fire

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    The cone flashing system depends on water running down into the cone and then around it and then off the tail. If anything obstructs that flowpath then the water will go sideways and behind the shingles into your home. You need provide that easy, low resistance, path for water to travel around the cone.

    I like to set the cone in place on the roof directly over the drill bit hole from below. Reach inside the cone with your yellow crayon and trace the inside of the cone onto the roofing. Cut the hole out. That will give you your 2" clearance. Then trim back another inch of roofing only. Then try and slide your flashing under the shingles and when you hit nails you will need to remove those nails. You will only slide the flashing up far enough to align with the hole in the roof.

    The base of the flashing is pretty big and your four nails are way at the edge. You'll never know if the nail was the leak point or if it went over the edge of the flashing, same result.

    Of course, you should be able to see the bottom of the tail. I get a kick out of the roofers that try and stick a shingle under the cone on top of the tail so that the only thing visible is the cone. That's a bad idea.
  15. shoot-straight

    shoot-straight Burning Hunk

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    when reflashing the crappy job my original installer did, they used "though the roof" its pretty cool stuff, will stick to things that are wet, AND fully cure even when its cold. remains a little flexible too, not as much as silicone, put ok. good stuff. i use it now on all kinds of stuff.
  16. Dogbyte

    Dogbyte New Member

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    ok cool, thanks guys i believe im on track now. would you say an inch from the edge of the flashing is good enough for the nails? and maybe 6 inches apart? how far up from the lowest shingle would you put your first nail on the sides, does it really matter as long as its not near the edge of being exposed?
  17. Dogbyte

    Dogbyte New Member

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    someone in my family, recommended this stuff to me, but i couldnt remember the name til you just mentioned it... he said it was also clear.
  18. Fifelaker

    Fifelaker Feeling the Heat

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    My goto product for anything that needs "Goo" is Solarseal 900. It beats silicone by a mile, it's pliable after 15 years , stick to most anything, comes in 200 colors (clear is one of them) $4 a tube.
  19. Dogbyte

    Dogbyte New Member

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    Well I checked two Home Depot stores and a Lowes, couldn't find the Through the Roof stuff. Had to settle with 100% silicone for the collar and Dap elastomeric clear roof sealant for any roof/shingle issues that may happen. Kit gets here today, I'm nursing a 3yr old that stayed home with the flu, who wants to take bets if it gets done today? =P I'm actually getting a lot of prep done that I wouldn't be other wise, I'd be at work if it wasn't for the little squirt.

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