Filling / sealing a gap against siding

[JHZR2]

Originally Posted By: doitmyself
I'm curious how you are going to address the bottom corners?

Aluminum and vinyl siding expand and contract quite a bit. Flashing/trim is supposed to be designed and installed so that it diverts water without caulk.

What are you planning to do with the J Channel at the bottom corners to keep water that is running down the J Channel from leaking behind the siding below....and then who knows where.


Also, I would have that unit tilting down 2% or more so the large top area will drain away from the house naturally.


The unit has about 1/2" slope per the instructions.

The old unit had that grey caulk around it as the only space filler and it was perfect and bone dry back there. If I just knew what that stuff was and how to apply, I'd likely be done.

 

[JHZR2]

Originally Posted By: doitmyself

What are you planning to do with the J Channel at the bottom corners to keep water that is running down the J Channel from leaking behind the siding below....and then who knows where.


Id really love some help or recommendations on this point as it is a good one.

Ive gone through three options - Al J, Al F and Vinyl J.

The Al channels are 1/2" so are too narrow to fit my siding.

The vinyl J is 5/8" so it fits the siding well and will work. The application is high enough off the ground that one will not be able to tell that it is a dissimilar materal.

So I can notionally J-channel out the hole, but what do I do at the bottom of the vertical runs? Just run an upside down J the whole width of the opening plus the width of the vertical ones and then caulk a LOT?

 

[doitmyself]

JHZR, I have no experience with your particular dilemma, but do understand the basics of flashing (roof, siding, etc.).

Your challenge goes beyond leakyseals recommendations because yours is a retrofit (not new siding install)that has very unique problems.

First, if you go to a real builders supply vs. big box, you are likely to find aluminum trim in many sizes to fit your needs.

This first link will show you the flashing concept I am speaking about: http://www.familyhandyman.com/DIY-Projec...siding/View-All Again, in theory, flashing/trim should work without caulking, except where you have "hard" butt joints.

This next link shows an unconventional way to trim out the J channel to divert water to the outside: http://www.nachi.org/forum/f16/j-channel-60633/ CLICK ON THE INTERNAL "ALBERTroofing" LINKS FOR SOME CHALLENGING INFO ABOUT YOUR PROBLEM. In this picture, it would seem better to cut a small notch in the bottom the the siding just above the J channel exit point to better allow water to escape.

Maybe overkill, you might consider an aluminum sheet "roof" with over hanging drip edges that forces the water on top to drip to the ground instead of over and into the unit back (we can explore this more.

Your big challenge is the retrofit nature of your project. As this picture shows, the vertical J channel water could end up behind your siding:

I have some more innovative ideas, but maybe a local expert at a real building supply store might have exact instructions for you.

 

[doitmyself]

While the "roof" I mentioned might be over kill, another idea is to skip the top J channel and install a "cap" of sorts that is inserted under the siding just above the top opening and extends an inch or two over the top of the unit as shown in your own link:

You will have to caulk between the vertical J channel and unit side. Check annually Also remember, just like roof flashing, you never caulk the "bottom" side to prevent trapping water. The concept that water always travels downhill plays into flashing design.

Window/door top drip:

 

[JHZR2]

Thanks. Was thinking about using that drip cap for the top, or flashing with my brake to get the same result.

The 5/8" vinyl j will work perfect and the location of the AC plus the fact that the trim will
be painted should make use of the vinyl ok. If I step down the ladder I already can't tell.

FWIW, the unit has been installed in the hole without the gap flashed or sealed, and everything around the hole and the wood in the hole has stayed bone dry, despite a few long and hard rainstorms. This may actually be far less critical than it seems... Though keeping drafts and cold air out in the winter is a concern.

I've gone through a bunch of those forums but will do a re-read. Thanks!

 

[JHZR2]

This is getting worse. Got the 5/8" j, cut it as one should so the water follows the tabs in the horizontal piece down the vertical.

I just can't get anything straight. Realize that I was stupidly trying and hoping to get this all to fit just by sliding the J under the existing siding. Of course it doesn't sit flat or even, so I can't get my mitre joints to sit properly or the thing to look right.

Maybe when I use sealant it would, but I don't want to take that chance as I doubt that sealant has much holding power, and I'm not going to be able to hold all the parts in place where I want them even if it does. I want to see it right on the dry fit and then be better when I put sealant on it. Not sure I'll have luck with that.

It's looking more and more like the entire side of the house has to be de-sided. Unfortunately no siding guys that I've contacted are willing to do that. Too small a job, even from the guys who say that no job is too small. I guess the economy isn't as bad as they say it is.

Very frustrating. Any other advice?

 

[doitmyself]

If it doesn't sit flat, maybe you need shims behind the J channel to bring things up even?

Are you doing the miters like in leakyseals picture or in my first link. It's kind of a fake miter, since the vertical pieces are cut square and only the top horizontal piece is cut at a 45 to appear like a miter.

The joys of remodeling!

5/8 aluminum J channel might be more rigid: http://www.wimsattdirect.com/products/PU_D_MFLC/PU_D_MFLC_050435.html

 

[JHZR2]

It doesn't sit flat because I can't nail it down without pulling the siding.

I did a real one, but am going to search for the 5/8 aluminum and try the fake miter. I'll probably also buy some snips like shown there.

 

[JHZR2]

Well I tried most every j channel, tried braking my own aluminum, etc. nothing worked. I needed at least 5/8" j and the vinyl didn't install well, the 3/4" aluminum (nobody around carried 5/8 Al at any supply house) was too short on the outer side to adequately cover and hide the gap.

So I used duct seal, PVC "wood" and aluminum flashing that I braked myself, then masked and applied white OSI Quad to the gap.

There was no way to apply backer rod, since it was siding and a hole in the wall, so I had to apply it pretty heavy. I got plenty in, tooled it a bit (though it says self tooling), then when it started to get stiffer, smoothed it real good with mineral spirits.

Not sure if you are supposed to tool self tooling sealants, or if you are supposed to use a solvent to smooth the work, but it came out looking fairly good considering it was a BIG gap, I don't usually caulk stuff and are not very good at it, plus I was working off a ladder.

We will see when it fully cures, and the worst tat can happen is that I pull it all and redo it... But some flexible sealant was how the old unit was in there, and it worked fine and was bone dry in there, so it must work well enough.

I'm planning on painting the AC and sealant (it's urethane and can take latex paint) when I have a chance.

 

[andyd]

You've lost me, but doitmyself's advice is the basic tenet of flashing. Lead the water down and out.

 

[JHZR2]

There was never any water in there. It's really just a gap close up to prevent cold/bugs/sideways rain from coming straight in.

But I just couldn't figure out how to flash it properly without ripping off the 50 yo siding on the house, which is painted, so then would be scratched. And it would all progress from there...

Since sealant worked before, it ought to work again, unless my skill messed it up...

 

[bigmike]

It looks promising to me. As long as it doesn't crack, it should be fine. Might be something you touch up on down the road, if so.