Vinyl Siding J-Channel caulking


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Old 03-17-23, 04:59 PM
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Vinyl Siding J-Channel caulking

During the last hurricane here in central Florida.... I had water come into the upstairs bedroom. The water was coming from around the windows. My first guess was the windows are leaking. I cut the drywall underneath the window and notice the wood was rotted in an area. I tried caulking wherever I saw a potential for leak on the bottom corners of the windows and any screw that might be exposed to the rain. I also replaced the weather stripping that was brittle and hard to make a better seal. Then we had some rain and I had left the drywall opened from before. I had covered the opening with plastic and painters tape to see if the leak stopped. The rain was not very heavy and it was not super windy and I saw drop coming through the rotted plywood. I broke the rotted wood loose and I was surprised there was no weatherproofing membrane behind the siding. I could immediately see the siding and then I looked up with the endoscope and I notice the drip seemed to be coming from the siding vinyl window trim aka J-Channel and not the edge of the window. If I am correct there should be weatherproofing all the way past that black thick tarp that leads to the attached porch. This house was built in 2001 and I can't believe it passed the city inspection without weatherproofing all the way down.

The leak is coming from the J-Channel around the window. I watched a YouTube video on bad siding installs and one thing he mentioned was the lack or no caulking in the inner part of the J-channel. But the lack of water humidity barrier of the last 2 feet at the bottom basically allowed water to wet the plywood and not run all the way down to the porch roof below. So water flowed down to the wood and eventually the floor instead of outside. I have caulked the windows, but never knew siding needed caulking. I assumed everything behind the siding was weatherproofed and that that if water got into the J-Channel it would just flow down and out.

I read here on another post here (Caulking J Channel around window) that caulking the J-Channel is not necessary, but then a YouTube video about bad siding installs says caulking is necessary in the inner part of the J-Channel. Which one is it?








 

Last edited by XSleeper; 03-17-23 at 05:07 PM. Reason: Removed unnecessary YouTube links
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Old 03-17-23, 05:06 PM
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It is not that it is not necessary, it's that it should NEVER be done. Vinyl has to be free to expand and contract. Any leaks are a flashing or housewrap issue and that is how its addressed.

Codes allowed people to install vinyl without housewrap until about 2006. You'd think it would be a no Brainer that you install felt... housewrap... SOMETHING on houses before you side them... thats the way its been done for ages... but when it was not specifically written in the code, builders omitted it and pocketed the money they saved.
 
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Old 03-17-23, 05:15 PM
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But in my case they did put a weather barrier and stopped before reaching the bottom. Basically they stopped where the window ended. Makes no sense not go all the way down. So they decided it needed it, but not the last two feet... lol crazy! The YouTube videos were of the videos I took of the leak situation. Sometimes pictures cannot provide a full picture.
 
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Old 03-17-23, 05:18 PM
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Its ridiculous too, because house wrap cannot be that expensive. How much are they saving on house wrap?
 
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Old 03-17-23, 05:24 PM
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The solution is to remove the bottom section of siding, replace rotted wood, add new wrap where missing and reinstall siding? I would put a new wrap underneath the old one and run it all the way down?
 
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Old 03-17-23, 05:45 PM
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Sounds like you are largely missing WRB behind ALL your siding. So you would need to remove all of it to install a WRB.

Your stop gap measure is described in the other post that you linked to. A metal flashing behind the leaking j channel that lays over the nail fin of the course below. That sheds water out to the weep holes of the siding, directing it away from the sheathing.
 
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Old 03-18-23, 03:11 AM
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And it's more than just the wrap, all windows need sill pans, flashing, and sealing when installed, it's a system to shed and direct the water away from the opening. If your seeing wood sheeting then something is missing.

 
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Old 03-18-23, 03:34 AM
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Hard to believe, but none of what Marq1 mentions was "required" by code in 2001 when your house was built. But current codes make it clear why you are having problems. That's why they say hindsight is 20-20.

At the time, window mfg's were just starting to recommend the use of flashing tapes and such as part of their installation practices... but these same practices were not required in building codes until 2006 IRC. Even so, mfg's instructions typically are supposed to supersede building codes when they require something that code does not.
 
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Old 03-18-23, 11:04 AM
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My mom has a small condo with wood windows. They are not great but every one of them is rotting due to how they were installed, or I should say how they were not installed.

Nothing, not a single piece of flashing, tape, or pan, So far I have replaced several, more needed, and I'm doing all the above to make the new windows, same crappy ones, last much, much longer than the original!
 
 

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