J Channel

[John Evans]

Inspected a new home yesterday and noted window J channel installation as non standard. Large national builder, supervisor stated the siding install was completed to their standards. Has anyone observed this J channel installation method?

[Peter C. Russell]

Hi John, it's installed that way to help prevent water penetration behind the siding. Cosmetically it doesn't look so good but effective. If you look at a roof where it meets a sidewall the J channel should be installed the same way.

[Brian A. MacNeish]

Originally Posted by jevans

Inspected a new home yesterday and noted window J channel installation as non standard. Large national builder, supervisor stated the siding install was completed to their standards. Has anyone observed this J channel installation method?


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There actually is a flashing technique that can be used at the bottom of the J-trim in behind the siding. Was published in JLC in early 1990's.

[John Evans]

Peter, Thanks for the quick response, learn something new every day! Attaching photos of a roof flashing install at same house.

[Marcel R. Cyr]

http://www.albertsroofing.com/Window...0Pictorial.htm

[Larry D. Kage]

What is pictured in post #1 is better than most slapped up J-channel installations.

At least, like Peter said, it directs the water out and away.

And here's another from the same website Marcel posted from:

http://www.albertsroofing.com/Window%20Flashing.htm

[Jeff Zehnder]

I would check out the siding manufacturer’s guiltiness...you still need the ability for it to move, expand and contract!

[Marcel R. Cyr]

Vinyl siding is not waterproof, despite common misconceptions. Thanks to its overlapping profile, a standard interlocking wall of horizontal vinyl panels will effectively shed most rain and water away, providing superior water resistance.
However, no vinyl siding is completely impervious to outside moisture from dampness rain or snow. For that reason, siding panels are manufactured with "weep holes" located at the bottom of each panel projection edge. These small but important outlets help channel away water that might find its way inside the siding wall through the panel seams and around moldings, windows, door and fixtures.

Weep holes also allow the infiltration of air, which also helps to dry out the inner surface of the siding while promoting evaporation of any remaining moisture.
The application of house wraps properly installed along with the right window and door flashings is of the upmost importance to provide for a secondary defense against outside moisture that might penetrate the siding and come in contact with the original sheathing.

The installation in the photo, might want to explaine the concept of not tucking you raincoat in your pants, but depicts poor asthetics, is not the standard Manufactures installation method.
Water will also find it's way between the J-mold and the window and door casing, which would allow water infiltration behind the siding anyways.

Even more reason to have proper flashing and WRB installed.

I would not allow for that type of installation.

[John Evans]

Thanks to all, Frank Albert was kind enough to email his opinion. Basically does not agree with the J channel install, will eventually leak. I like to refer to the Vinyl siding Institute installation manual. None of their diagrams show a J channel install like the one from yesterday.

[Brian A. MacNeish]

Originally Posted by Brian A. MacNeish

There actually is a flashing technique that can be used at the bottom of the J-trim in behind the siding. Was published in JLC in early 1990's.

http://www.finehomebuilding.com/PDF/Free/021149082.pdf

At the right of Page 5 is a picture of a so-so attempt of' "behind the siding" flashing at the bottom of window side J-trim. With this method, the water from the J drains into the "hook" of the panel and runs horizontally to an open siding joint or corner trim, then to the siding exterior or ground.

I don't like using tar paper for this purpose but something better like aluminum coil stock cut for the purpose.

[Frank Albert]

"Vinyl siding is not waterproof, despite common misconceptions. Thanks to its overlapping profile, a standard interlocking wall of horizontal vinyl panels will effectively shed most rain and water away, providing superior water resistance."

We heard this so many times that some years ago, we nailed several pieces to some posts. This way we could see both sides. Then, we turned a water sprinkler on the faus wall and let it run for two days. Lo an behold, the back side never even got damp. It is water proof.
The siding people at all levels perpetuate this myth so they look blameless when the structure rots out behind the siding.

My brother and I spent months working on solutions that kept the water out, even when the house washers come by with their pressure washers. It's possible to keep all water out by paying attention to detail just as if it was a roof going on.

[Frank Albert]

"What is pictured in post #1 is better than most slapped up J-channel installations.

At least, like Peter said, it directs the water out and away."

Yeah. When it gets to the piece of siding that is pressed againstt he J-channel, it will get directed out and away from the J-channel, and behind the siding. That will work as well as a clogged valley, or stopped up downspout. The 2" J-channel with openings all along it's sides doesn't do anything but dress up the openings.

BTW, I have recently updated my tutorial page to clarify lenghts of flashings, and such things as why I used duct tape in the model... It's easier to pull the model down and reuse it to teach people how to flash a window.