# Hardie Plank Siding - Horizontal/Vertical Flashing



## stubits (Dec 30, 2008)

Hey Folks, need a little bit of guidance here. I am planning to install Hardie Plank siding on an addition to my home and there is one area where vertical L flashing intersects with horizontal Z flashing. I would imagine it is installed such that the L flashing is on top of the Z flashing, right? Do I need to caulk the joint between the two flashings? 

See the picture below from Hardie's install guide and it pretty much shows my situation, it just doesn't show how the two flashings meet. 

Any help would be much appreciated!


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## kwikfishron (Mar 11, 2010)

I caulk all of my flashing laps. I’d also put a bead on the inside of the brick and set the L into it. Make sure the L laps over the top of the Z.

You might have to bend your L slightly out of square so it's a nice tight fit in the corner.


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## stubits (Dec 30, 2008)

Excellent. That was my thinking. 

What caulk do you use?


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## kwikfishron (Mar 11, 2010)

I use Vulkem or Quad. Make sure to "Blind Caulk" you whant just enough to seal without seeing it.


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## stubits (Dec 30, 2008)

In this case, wouldn't the caulk be covered by the siding? I know I need to caulk between the siding and the time, but I want to make sure, I should also caulk the seam where the two pieces of flashing meet, right?


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## kwikfishron (Mar 11, 2010)

stubits said:


> In this case, wouldn't the caulk be covered by the siding? I know I need to caulk between the siding and the time, but I want to make sure, I should also *caulk the seam where the two pieces of flashing meet, right?*





Correct and also caulk the flashing seams were the Z overlaps if you have any.


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## stubits (Dec 30, 2008)

Awesome, thanks.

Hey, a related question...

From what I have read, I need to install Hardie Trim to prevent Hardie Plank from butting up against brick, right? If that is the case, then this is more of an aesthetics question, really.

In the attached image, the yellow represents all the place I think I need Hardie Trim, even though I'd prefer not to use it on the two smaller applications. Is there anything I can do to avoid using it there?

If not, the red lines indicate where I don't have to use hardie trim, but might just for looks. What do you think?


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## kwikfishron (Mar 11, 2010)

Any ware the siding buts into brick there need to be some trim to butt into. Personally I use a 2x2 cedar, it’s something to butt into but not as noticeable as a 2x4 or something. Whatever trim you use against the brick make sure get a lot of caulking in that corner to embed (blind caulk) the trim into. This is one spot were you want to waste some caulking but without making a mess out of it. And make sure your using a polyurethane like Vulkem, not silicone.


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## stubits (Dec 30, 2008)

Hmm, hadn't thought of using cedar, might be nice to have something smaller than the trim. I will think of that.

When applying the caulk, do you apply it before or after you install the siding? I assumed I would

1) Apply bead of caulk
2) Apply flashing over bead of caulk
3) Apply trim
4) Install siding, leaving 1/8" gap between siding and trim
5) Install bead of caulk in gap left between siding and trim


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## kwikfishron (Mar 11, 2010)

stubits said:


> Hmm, hadn't thought of using cedar, might be nice to have something smaller than the trim. I will think of that.
> 
> When applying the caulk, do you apply it before or after you install the siding? I assumed I would
> 
> ...


 
With Hard both, #3.5 sould be another bead of caulk from trim to wall. 

Not everyone does this and might not be necessary in a dry climate but all of my stuff is on the Or. Coast so we take extra steps that you probably wouldn’t in Arizona or the like.


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## stubits (Dec 30, 2008)

Not sure I understand. Where exactly should I caulk when you say from the trim to the wall? Does that mean caulking OVER the L flashing?


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## kwikfishron (Mar 11, 2010)

Once the trim is on and your ready to start siding I run a bead down the inside corner of the trim the siding will butt into so if your final face caulking fails (the caulking that gets exposed to the weather) there is extra protection behind that so water can’t get behind the trim.


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## stubits (Dec 30, 2008)

Awesome idea, thanks!


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## stubits (Dec 30, 2008)

So, you seem to have lots of experience. Are you a fan of the Hardie products? Am I making a good choice here?

Also, obviously the Hardie trim does not come in lengths that will run the full height of my house. Is it better to make the cuts/seams between floors or does it not matter?

Going back to the image I posted earlier, would you use trim where I have drawn the red lines or just leave the siding? What will look best? If I install trim there, would the 7 flashing go above or below the trim?

Any other suggestions for working with this material or pulling off this job?

Thanks!!


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## kwikfishron (Mar 11, 2010)

You had to ask me that.

I think Hardi is a good product as far as it won’t rot. When it first came out it was the new “builders choice” to replace the old choice which was LP Siding. We all know what happened with LP. I was skeptical at first so I broke off a piece of Hardi and stuck it in a bucket of water. 6 months later it looked the same as when I put it in there. 

What more can you ask for, it’s a good durable product to protect the house.

What I don’t like about Hardi is that it will show every imperfection on a wall and magnify it. Looks great from the street but get up close put your face against a big wall and look down that and you’ll see what I mean. Now this doesn’t bother most but that kind of stuff drives me nuts. Also, Hardi’s most common panel that everyone stocks is the 8 ¼” for a 7” exposure. They tell you to blind nail it. Any 7” blind nailed Hardi wall you can easily get your fingers under a lap and rip the piece off if you wanted. If I can do that then tell me water can’t get through there when it’s blowing 80 and raining sideways like it does quite often here. The 6” exposure is much better and the 5” it tight like I’d like to see it. 

I think properly installed cedar shingles are by far the best protection for a house but of course they cost a lot more than Hardi. If your going to use Hardi I’d think about a 5 or 6” exposure.


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## stubits (Dec 30, 2008)

Wow, thanks so much, really good to know your thoughts.

So, my architect is calling for an 8" exposure so that the siding lines up with the brick. How bad is that going to be? Worse than 7" for sure!


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## kwikfishron (Mar 11, 2010)

stubits said:


> Wow, thanks so much, really good to know your thoughts.
> 
> So, my architect is calling for an 8" exposure so that the siding lines up with the brick. How bad is that going to be? Worse than 7" for sure!


If it was siding matching to siding then yes but siding to brick, thats up to you. I have ran siding to brick many times and never even thought about wanting the lines to match.

I'll throw you some more later, to nice out side to hang in here anymore.


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## stubits (Dec 30, 2008)

Hmm, very interesting. It made sense that we'd want the siding and the brick to match up BUT given that we need to use the trim, it won't really matter, will it? A tighter fit is certainly better. Thanks for the heads up!

Also, going back to my original question, as I read through the Hardie Best Practices guide a bit further they don't explicitly say that trim needs to be installed where siding butts into masonry, instead it says, "flashing should be installed to isolate the trim or siding from mortar or masonry." Can I install the siding with the L flashing or is it necessary to also include the trim?

Be sure to enjoy the weather, I am stuck in my office, so this is at least a diversion. I appreciate your help and guidance tremendously!


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## stubits (Dec 30, 2008)

bump.


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