# Capping windows with aluminum VS flashing with aluminum



## HomeSealed (Jan 3, 2008)

That is not proper and will result in leakage if I understand you correctly. Every opening needs a drip cap (flashing) above it that goes back to the sheathing. Caulking aluminum window trim to the vinyl J-channel is not sufficient because moisture/water WILL get behind vinyl siding(that's why there are weep holes in the bottom of the siding), and therefore into the window opening if it has no drip cap.... Also,yes, the aluminum trim should be caulked to the window as well


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## tpolk (Nov 7, 2009)

I am in the process of replacing windows,drywall, sheathing etc from an install almost exactly like yours


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## scott j (May 4, 2009)

*flashing top*



HomeSealed said:


> That is not proper and will result in leakage if I understand you correctly. Every opening needs a drip cap (flashing) above it that goes back to the sheathing. Caulking aluminum window trim to the vinyl J-channel is not sufficient because moisture/water WILL get behind vinyl siding(that's why there are weep holes in the bottom of the siding), and therefore into the window opening if it has no drip cap.... Also,yes, the aluminum trim should be caulked to the window as well


Just so I understand, does the top need to be flashed OR the top and all sides plus bottom need to be flashed also? 

He might have flashed just the top of the window and then slipped it in under the J-Channel.


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## HomeSealed (Jan 3, 2008)

That is a very common occurrance in replacement window installation. Half the time, guys wrap OVER the existing drip cap, rendering it useless. It is a shame, and is why you should be careful choosing a company. Not to scare you, but if this guy tried pulling this on you, who knows what other corners were cut... OR, even worse, maybe he just doesn't know the right way to do it.


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## scott j (May 4, 2009)

Thanks for the info...I am gonna check all the windows when it gets warmer. Does the caulk need to go on both sides of the aluminum capping, J-channel side and window side? Or just the J-channel side?


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## HomeSealed (Jan 3, 2008)

scott j said:


> Just so I understand, does the top need to be flashed OR the top and all sides plus bottom need to be flashed also?
> 
> He might have flashed just the top of the window and then slipped it in under the J-Channel.


Primarily the top, that is where water would enter behind the siding...You cant really "just slip" a drip cap behind the j-channel. It really needs to be installed prior because it needs to run up the vertical surface of the wall.....does that make sense? It should be like a L with a little lip coming down over the front face of the window. How could he have "slipped" it behind there with the nails of the j-channel in the way? Not only that, it needs to go behind the foam, and the building paper.


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## scott j (May 4, 2009)

*Yes*

Yes. It needs to go up farther than the J-Channel on the top of the window. Got it. Thanks again.


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## HomeSealed (Jan 3, 2008)

Right. See my edit, it also needs to be behind the foam and the building paper


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## scott j (May 4, 2009)

*Hmmmm*

Thanks. I wonder how soon I need this fixed? A week or can it wait until it gets a little warmer?


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## scott j (May 4, 2009)

*One more thing*

The L shaped drip cap...does the windows capping then go over the top of that for a 2 piece system on the top of the window OR is it all one piece for the top of the window. 

I am trying to make sure I have this down correctly. Sorry for all the questions.


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## MJW (Feb 7, 2006)

I imagine he slipped it in for inspection. The inspector should smart enough to know that the top J channel should NOT be sealed. If flashing is done properly an a new window, it should of no concern, but if it's a capped older window you need the flashing to go up the wall.

A flashing can't get water out from behind the siding if it is sealed to the J channel.


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## HomeSealed (Jan 3, 2008)

scott j said:


> The L shaped drip cap...does the windows capping then go over the top of that for a 2 piece system on the top of the window OR is it all one piece for the top of the window.
> 
> I am trying to make sure I have this down correctly. Sorry for all the questions.


 No... and unfortunately that is often what is done. The window wrap (capping) needs to be UNDER the drip cap, also as MJW mentioned, it cant be caulked either, otherwise the water has no where to exit. It is okay to laeve it for a little bit, but I wouldn't wait too long to get it addressed.


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## scott j (May 4, 2009)

*Thanks Home Sealed*

Thanks Home Sealed. I appreciate all of the info. 

Just to be clear, I also had new siding added to an addition on the house that had new Pella aluminum clad windows. For the new windows, the guys taped the window to the housewrap with Pella tape (except on the bottom). 

But like I said earlier, flashing was not done for the old wood windows on the original part of the house. They were just capped with aluminum and caulked.

Do I need to have flashing done on the NEW Pella Windows? Those looked like they had flashing built in that was taped to the housewrap.

Thanks


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## HomeSealed (Jan 3, 2008)

On those Pellas, that nailing flange can act as the flashing, however, the proper procedure is to have it taped to the sheathing and the house wrap over it on both the top and the sides.... The more you explain here makes it seem like these installers really didn't know what they were doing.


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## scott j (May 4, 2009)

*no they didn't*

I had to tell the guys to NOT put tape on the bottom of the window as that is what Pella says. I have seen the tape done both ways.


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## HomeSealed (Jan 3, 2008)

scott j said:


> I had to tell the guys to NOT put tape on the bottom of the window as that is what Pella says. I have seen the tape done both ways.


 The bottom should NEVER be taped. In terms of top and sides, the OLD way was to wrap the tyvek into the hole, then tape the window flange to the tyvek. Then when people started noticing that tyvek can fall apart over the years, it is now official policy of every manufacturer and procedure that the flange be taped to the sheathing and housewrap goes over it. Anybody still taping to the wrap is outdated and uninformed.


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## scott j (May 4, 2009)

*Recommend*

Hi,

do you know of a good company in the Chicago area? thanks


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## MJW (Feb 7, 2006)

HomeSealed said:


> The bottom should NEVER be taped. In terms of top and sides, the OLD way was to wrap the tyvek into the hole, then tape the window flange to the tyvek. Then when people started noticing that tyvek can fall apart over the years, it is now official policy of every manufacturer and procedure that the flange be taped to the sheathing and housewrap goes over it. Anybody still taping to the wrap is outdated and uninformed.


Actually Tyvek falls apart from UV rays when it isn't covered up quick enough. 
The house wrap is our rain shield.


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## scott j (May 4, 2009)

*A possible solution ?*

It is covererd with siding. Just have to flash the windows properly in the spring.

Which brings up a final question for a solution.

Since my carpenter didn't install the windows properly with the building paper over the top of the windows (he went under and then taped it to the top of the window) wouldn't it make sense to leave it and then flash with aluminum over the top of that?

What I mean is that I don't want to make a problem worse by trying to pull off the tape, cutting and damaging the building paper. Rather, slide the aluminum flashing under the building paper higher than the top window flange. So any water that runs down the building paper hits the aluminum first before hitting the taped window flange.

Thanks,
Scott


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## HomeSealed (Jan 3, 2008)

MJW said:


> Actually Tyvek falls apart from UV rays when it isn't covered up quick enough.
> The house wrap is our rain shield.


I realize that it is the rain shield, however that does not change the fact that wrapping the tyvek into the opening on all sides is deemed incorrect . Further, I have personally seen siding jobs (not new construction) where the tyvek is disintegrating years later. I can't say the specific reasoning for this, but unless UV rays pass through vinyl, that isn't why. This isn't an isloated thing either, I'm sure there are a lot of other pros who have seen the same.


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## MJW (Feb 7, 2006)

HomeSealed said:


> I realize that it is the rain shield, however that does not change the fact that wrapping the tyvek into the opening on all sides is deemed incorrect . Further, I have personally seen siding jobs (not new construction) where the tyvek is disintegrating years later. I can't say the specific reasoning for this, but unless UV rays pass through vinyl, that isn't why. This isn't an isloated thing either, I'm sure there are a lot of other pros who have seen the same.


Haven't had much for wall coverings up here older than 10 years or so. The ones I have seen that were deteriorated were homeowner jobs that took months to get covered.

There is one house down the road from me that they put an addition on 3 years ago. They still have not sided it. You can hardly read the name on the wrap.

The Rep at a sales meeting said that the deteriaration is caused by UV rays and not getting covered. I can't say I have seen any other Tyvek on our jobs that was that way without it being exposed for long periods. Usually it was a slow, incompetent contractor or homeowner. Usually that is why we are there......to fix the mistakes.


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## scott j (May 4, 2009)

*Fix and tape Window Flange to Sheathing*



HomeSealed said:


> The bottom should NEVER be taped. In terms of top and sides, the OLD way was to wrap the tyvek into the hole, then tape the window flange to the tyvek. Then when people started noticing that tyvek can fall apart over the years, it is now official policy of every manufacturer and procedure that the flange be taped to the sheathing and housewrap goes over it. Anybody still taping to the wrap is outdated and uninformed.


So, the question is....do I remove the TAPE on the top of the window, cut just the Tyvek on top, then tape the Window flange to the sheathing? Or just cut the tape and the Tyvek so as not to destroy the Tyvek by ripping off the tape? Thanks


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## HomeSealed (Jan 3, 2008)

The proper sequence is : flange caulked to sheathing, tape over flange, tyvek over tape.


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## Tom Struble (Dec 29, 2008)

earlier versions of tyvek did break down under the cladding

that tyvek had a very smooth texture, the newer ''improved'' tyvek has sort of a checker board texture and supposedly does not get brittle


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## Michael Thomas (Jan 27, 2008)




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## Michael Thomas (Jan 27, 2008)

scott j said:


> Hi,
> 
> do you know of a good company in the Chicago area? thanks


At my own properties, I use:

http://www.swistun.com

they perform the highest quality replacement siding jobs I've seen - they are absolutely _meticulous_ in their detailing.

(For the record, my only business relationship with Swistun is writing them large checks.)


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## scott j (May 4, 2009)

Thanks everyone for the comments. Here is the rest of the story:

1) For the new Pella Windows that were not taped properly, they installed a drip cap over the top of the aluminum window cap. I made them tape the drip cap to the sheathing and not the Tyvek. So, if water comes down the wall beneath the siding, it will hit the drip cap first and not the Pella window that is taped to the Tyvek. This was less work than having to remove the Aluminum window capping and filler wood on the top. Luckily, the 2nd floor windows are right under the 2' overhang so I didn't worry about those.

2) For the old windows, those are in the process of being all redone with adding aluminum capping that is flashed on top and caulked on the inside Aluminum capping to inside of window.
I ended up hiring a different siding company to fix the problems.


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## scott j (May 4, 2009)

*What about a Deck Ledger Board?*

I have aluminum flashing behind the J-Channel / Siding and over the top of a ledger board for a deck(bolted to house). Should that also be taped to the Sheathing? I don't think it is taped to the Tyvek or Sheathing.


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