# J channel at the wall to roof transition



## joecaption (Nov 30, 2011)

Anyone else confused about where he's talking about?
Got a picture?


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## Dixon12 (May 3, 2016)

joecaption said:


> Anyone else confused about where he's talking about?
> Got a picture?


No actual pic, but here's a sketch. If I nail the j over that headwall flashing, wouldn't water get in through the nail holes?


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## waterman1971 (Apr 19, 2009)

Nail it!!! Nail holes are higher than the front lip...


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## Windows on Wash (Aug 30, 2011)

Roof to wall intersections are certainly going to be your top 3 in terms of leak pathways in roofs. 

Is the roof new? If so, hopefully they sealed that connection by running some Ice/water up the side wall and behind the step flashing. 

If not, you can apply some self healing membrane over sheathing and up the side wall slightly. You need to have the J-channel space appropriately high enough off of the roof surface to make sure it does not warp with heat. 

You would still run your WRB over the step flashing in this case and because most folks don't like the look of the slightly exposed step flashing (when your clearances are right), many times you can put a piece of counter down and over the step flashing and behind the J-channel. 

At that point, you only need to nail through where the self-healing membrane is and you have the proper spacing as well.


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## Dixon12 (May 3, 2016)

Windows on Wash said:


> Is the roof new? If so, hopefully they sealed that connection by running some Ice/water up the side wall and behind the step flashing.
> 
> If not, you can apply some self healing membrane over sheathing and up the side wall slightly. You need to have the J-channel space appropriately high enough off of the roof surface to make sure it does not warp with heat.
> 
> ...


The roof isn't new, about 10 years old and the whole thing wasn't done so well. No leaks AFAIK, but there is no sheathing, just wood siding nailed to studs, a piece of aluminum nailed over the first course of siding and over the shingles. There may be some flashing behind that that would go under the siding. So pretty sure no ice/water barrier there, just nowhere to put it on unless they slapped it over the siding. They, or the previous owners, did like their caulking a lot, had some things that were hanging in places just by caulk, so I'm really not sure what, or how much of it is under there.

I'll be ripping out the old siding, sheathing as close to the roof deck as I can get, and then plan to flash it properly. I don't want to start tearing out the shingles, but may have to remove a course or two if would have to add ice/water barrier. Hopefully they put some up at the top of the roof deck so that I'd be able to just add some over sheathing and over part of the old barrier. I see no reason why that wouldn't work. 

As for the flashing, the roof line if flat, so would I still need to use step flashing? Or just transition flashing going 4" each way?


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## Windows on Wash (Aug 30, 2011)

If there is step flashing already (should be), you don't need to re-do that. You will be creating a counter flash detail with a kick out detail at the eave to work with your new J-channel and siding.


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## carpdad (Oct 11, 2010)

You're in IN so ice damming can happen. Snow dams there, heat from wall and roof melts the snow from inside and dammed water flows uphill between all joints into the interior. When insulating from inside, I'd use combo of 1/2" foam boards against the sheathing and spray foam all joints. Later, caulk the drywall joints and foam the outlet holes, etc. No draft points as best.
Outside remove a foot of shingles, put down ice shield half and half and roof and side. I'd go another course ice shield on the wall. Really need to be careful about flashing around the j channel and windows. Average thought these days is flash under the leaky roofing and siding, and let the rain flow under these structures-and let the tyvek take care of it.
Same idea with that image. Top shingles are on top of the metal flashing. Idea is it looks good and let some of the water go under the shingles.:surprise: Use heavy gauge aluminum sheet, bend with brake (some homedepot rents it), dark side out, and 6" cover. Search (days if necessary) until you see flashing detail that you intuitively see for the protection it gives. I'm saying trust your eyes, only after learning a lot about it.:smile:
I see many posts here who have no idea where the leak is coming from. What I want to say to them is rip it all out and do over.

BTW, you will want to block between the studs for top and bottom edge of the new sheathing. If that roof is outside, may want to put sheathing against the roof space, foam all gaps against draft, then insulate. That roof space may need vents.


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