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-   -   Capping windows with aluminum VS flashing with aluminum (http://www.diychatroom.com/f15/capping-windows-aluminum-vs-flashing-aluminum-63535/)

scott j 02-03-2010 03:15 PM

Capping windows with aluminum VS flashing with aluminum
 
Hi,

I recently had old shaker shingles removed from my 1920's American Four Square house and replaced with vinyl siding. The contractor removed the old aluminum capping around the windows as it was caulked to the old siding. He also added Polar foam board over the existing tar paper house wrap.
My question is, on some of the windows he flashed the old wooden window trim with aluminum, then sided the house, but then came back and finished the rest of the windows by sliding the aluminum capping over the wood window frames (not-flashed because J-channel was now in the way). He said either way it doesn't really matter because he caulks the J-Channel to the outside of the aluminum on all sides except the bottom.

Does this sound logical? Also, should he caulk on the inside of the window and the aluminum as well?

Thanks

HomeSealed 02-03-2010 04:15 PM

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

tpolk 02-03-2010 04:38 PM

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

scott j 02-03-2010 04:44 PM

flashing top
 
Quote:

Originally Posted by HomeSealed (Post 394217)
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.

HomeSealed 02-03-2010 04:46 PM

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.

scott j 02-03-2010 04:51 PM

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?

HomeSealed 02-03-2010 04:52 PM

Quote:

Originally Posted by scott j (Post 394227)
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.

scott j 02-03-2010 04:56 PM

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

HomeSealed 02-03-2010 05:01 PM

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

scott j 02-03-2010 05:07 PM

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

scott j 02-03-2010 05:13 PM

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.

MJW 02-03-2010 05:15 PM

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.

HomeSealed 02-04-2010 03:15 PM

Quote:

Originally Posted by scott j (Post 394250)
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.

scott j 02-05-2010 10:25 AM

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

HomeSealed 02-05-2010 10:42 AM

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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