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Discussion Forum

Where to seal window flanges

workdog2 | Posted in Construction Techniques on September 9, 2007 06:14am

Some say (Grace Products & Others) to seal window flanges with Vycor all purpose flashing membrane tape,all 4 flanges directly to the SHEATHING not to the felt or housewrap, incase of a Tear or puncher in the felt or wrap.Then applying the felt to the wall surface. FINE HOMEBUILDING Articles states install window flanges on top of felt by tucking the top under the felt leaving the bottom & sides on the top. Then applying the flashing tape to first the bottom flange then the sides to the felt,over lapping the bottom.Then apply the flashing tape under the felt & over the upper flange directly to the sheathing over lapping the side flashing. The bottom can be left unflashed if using a drain pan.

neither states silicone under flanges,but the window manufacture says silicone first,then flashing but doesn’t say what surface to seal to with the flashing tape.

Do we really need felt or wrap under the flange with the silicone than the flanging tape??

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  1. dovetail97128 | Sep 09, 2007 07:08pm | #1

    workdog,

    I keep it real simple.

    Think about the window as if it were a roof shingle, you want the water to come down onto it from above and to leave it over the felt/water barrier below.

    Done carefully I don't think one needs the caulk, vycor or anything else for water protection.

    But I use them anyway as for air infiltration.

    "Poor is not the person who has too little, but the person who craves more."...Seneca

    1. rez | Sep 11, 2007 07:21pm | #2

      A Breaktime Appreciation Award goes to dovetail for his continued support of the forum.

      Saaalute! View Image

      sobriety is the root cause of dementia.   

      1. dovetail97128 | Sep 12, 2007 04:37pm | #4

        rez, Shoot man I am a rookie here. got to be others who have stuck around and contributed more. Appreciate the thoughts though. "Poor is not the person who has too little, but the person who craves more."...Seneca

        1. rez | Sep 12, 2007 07:53pm | #5

          Shoot man I am a rookie here. got to be others who have stuck around and contributed more.

          Ya, but actually there's just a handfull of folk that field the questions on a regular basis and they all deserve an award too.

          be keeping the home fires burning

          Edited 9/12/2007 12:54 pm ET by rez

  2. Piffin | Sep 12, 2007 12:12am | #3

    just keep all your lapps facing downhill

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
    Excellence is its own reward!

  3. SBerruezo | Sep 13, 2007 07:31am | #6

    I was taught more or less a combo of the last two...Felt/paper/wrap/whatever, then vycor bottom and sides, set window in caulking that's around the perimeter of opening, then run the top strip of vycor.

    Whether or not that's best practice, I don't know. I'm always curious when I hear and see so many ways of doing things.

     

    1. workdog2 | Sep 14, 2007 09:49pm | #7

      SBerruezo Thanks for the reply. I hear you loud & clear ! Seems there's to many ways to do things now days. I guess to fill everyone needs. I'v been think along that way also,but I'v never been taught on the subject so,with so many ways it gets confusing at times. Here's another, how to install the alum. "J" channel around the windows? Now Andersen says to install siding & trim 1/4" from window unit for sealing (Backer-Rod than caulk) Also they now want a drip cap. The cap makes the J stick out from the window unit leaving a gap for a leak. But I GUESS if you leave the 1/4" for sealant it won't matter. Wondering doe's this mean all siding (alum,vinyl) or just wood or what.

      1. SBerruezo | Sep 14, 2007 11:10pm | #8

        One other thing I thought of is that if you have any questions on best practice, it's probably a good thing to follow the manufacturer's instructions to the T.I've heard that if you deviate from the manufacturer's instructions, even to improve upon them, it voids any warranty. Don't know if that's true or not, but given the litigious society we live in, it wouldn't surprise me.I've never dealt with aluminum or vinyl siding, so I'm not the one to answer your next question, but a lot of guys here are more than capable of it.Caulk joints have sort of depended on how I've installed the trim, but I generally try to get my siding close to the trim (1/8"ish) and caulk the rest to allow for expansion and contraction. This, I would guess, is the primary reason the manufacturer's are calling for the 1/4" gap, and the amount of gap will likely depend mostly on the properties of the siding.
         

        1. workdog2 | Sep 15, 2007 05:21pm | #9

          Your probably right about the warranty thing. I did finally get to talk to someone at Andersen who new something about installing windows. One of their Architects who was very helpful with answers about their products. It was amazing to talk to some one who new something after talking to some numb heads from the same company!!! Incase you ever need some information about Andersen windows & for your post time to me, Here's something you may could use in your future challenges with windows.

          Fred 1-651-264-5593 Andersen Windows (Architect) SORRY didn't get his last name.

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