Kickout flashing penetrating siding - should I caulk it?

Good evening, everyone. Now that the roofing is complete, I have started to work on replacing siding I removed. I am using Hardie Siding. The part where kickout flashing is exiting through the channel in siding, should I caulk this channel? Caulk would connect the siding to the kickout flashing, prohibiting any water from ingressing. Not worried much about the bottom part, since it is inside the flashing and water will simply carry out normally, but the very top of the channel where the water can elect to travel behind the flashing and into the wall. Very small space. Of course, I have Tyvek Wrap there that transitions onto Grace that would bring any water out of siding onto painted treated wood trim. But want to eliminate the use of this backup system by preventing any unlikely water ingress.

Looks perfect.
I would round the metal off but that is just cosmetic.

I would caulk the back of the kick out to the top of it.

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Just me, but because of the lap location, no kick out was needed. The first tin shingle would never have allowed water behind the siding and it would have looked better. Once again, just my thought.

There is no problem here but it is more of a stucco detail kickout. Siding doesn’t need that aggressive return and a shorter kickout under siding lap would have accomplished the same thing.

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I’d caulk where the siding is meeting the metal on the front, top and back to prevent any wind blown rain from entering. Do not caulk the bottom edge of the siding to the metal to allow any water to drain if it gets behind the siding.


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Thanks, everyone for the input. I was planning to caulk behind and at the very top of the flashing. The front side of flashing is not as critical, since any rain that gets there will be inside the kickout flashing and will easily carry out, but I reckon it will not hurt to caulk there too to reduce the amount of water that can be blown in - and possibly travel upwards via capillary action behind the siding. I am planning not to caulk the bottom of siding anywhere, so water can escape. Funny thing is that the rest of house has siding caulked on the bottom, but like the shingles, I feel it should remain flush but uncaulked to allow any water that penetrates to escape. The reason by I went overboard with kickout is for function over form - the original builder had none at all, the entire side rotted down to support beams. It was pain replacing all the rot. Once the gutters go up, much of the flashing will be hidden.

So caulking the kickout on both sides and top should not lead to any trapped moisture, right?

I would leave the bottom half of the front(roof side)uncalled, just so water passes cleanly



I read in my roofing textbook that cutting that corner off can make the kickout appear smaller than it is. You suggest simply rounding off the corner? Would you make a semi-circular cut from middle of one plane to middle of other plane or round off just a smidge? I want it to look less bulky without reducing its usefulness. Doubt I will ever have much flow through it as it is covered by an 18 inch overhang from roof plane above, but some water does flow through it during heavy rain.

I’d do something like this:

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