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Flashing James Hardie Artisan butt joints installed on furring strips?

kurtgranroth | Posted in Green Building Techniques on

My question is this: How do I treat/flash the butt joints of James Hardie Artisan planks when installed on furring strips?

My house has continuous foam insulation acting as the WRB and then 3″ x 3/4″ furring strips installed 24″ O.C. to make up a rainscreen and give a solid surface to attach the siding to.

My siding is James Hardie Aspyre Artisan Shiplap planks, their “luxury” line. It’s still fiber cement but different enough that it has its own unique instructions (“Artisan Siding with Lock Joint System”). The instructions do say “James Hardie recommends installing a rainscreen (an air gap) between the Artisan siding and the water-resistive barrier as a best practice” but that’s literally the only reference to it in the doc. All further instructions assume installing it directly on the WRB.

There is a section with details on treating the butt joint with a caulk option (not recommended) and a joint flashing method (recommended with detail drawings). The drawings seem to show it installed directly on the WRB and that particular detail is very commonly shown in any number of random JH install videos.

Perhaps I could just land all butt joints on my furring strips and flash the joints there?

Two more things they dictate.
1. You may not nail within 2 inches of the end of the plank
2. The butt joint must not fall within 4 inches of a stud

Since my furring strips are 3″ wide and the nails will be a minimum of 4″ apart at the ends AND it can’t land on a stud (furring strip in this case) at all, that means that my butt joints will be floating out in space, 3/4″ in front of the WRB/continuous foam.

So that leads me back to my initial question. Since I can’t tape the top of my flashing to the WRB (3/4″ back, again), how would that even work?

Finally, there is a video from James Hardie EU that shows installation of “Hardie Plank” which is super similar… but the installation methods are different enough (they use screws instead of nails, for instance) that I don’t think it’s very applicable. There is also a Technical Bulletin describing installation on furring strips, but it makes zero reference to butt joints and entirely focuses on weight loads for different types of furring material.

Any ideas?

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  1. nynick | | #1

    Call Hardie and ask for the rep in your area, then document his reply.
    I'm looking to do something very similar.

  2. tfullerton | | #2

    I can't wait to hear the answers!

  3. kurtgranroth | | #3

    I got an answer from James Hardie but I'm not liking it. The answer was the following, with the attached image:

    "[C]ut the flashing longer and over-lap the plank below, then tape the top to the weather wrap"

    That doesn't sit well with me. The weather wrap (foil-based foam in my case) is 3/4" behind the siding, so taping the top of the flashing to it would create a ramp for any water coming down the rain screen from directly above to instead redirect to the front of the siding. Why would I want that? Any water in the rain screen is already in the ideal place for water since it's a straight shot down and out over a seamless waterproof barrier. And any residual moisture from wetting the foil would dry quickly with the airflow up that rain screen. Redirecting a random part of the water to jet out the front of the siding seems pointless.

    Thinking about it m0re, I'm not fully convinced that flashing is even necessary if installing over a rain screen with the butt joints landing in space. If water does get through the gap (and it will), then it has a clear path down and out with great drying potential afterwards.

    But... I probably will do something, anyway. I'm thinking now of doing the flashing as described but instead of attaching it to the WRB/foil, I may tape it to the back of the siding itself. That way, when rain does get through the butt joint, it won't get any farther than the thickness of the siding before hitting the flashing and immediately being redirected down and out.

    Thoughts on that?

    1. Patrick_OSullivan | | #4

      > Thinking about it m0re, I'm not fully convinced that flashing is even necessary if installing over a rain screen with the butt joints landing in space.


    2. Expert Member
      Akos | | #5

      I really don't see the issue with what they ask. The flashing strip is small enough that it won't block rain screen cavity to effect drying capacity and if you have enough bulk water coming down to damage the back side of the siding, you are in bigger trouble than a bit of paint peeling. Also, you are now following the manufactures instructions.

      For this flashing strips, what I found works is getting a small house wrap roll (say 3' one) and cutting it to 8" mini roll on a miter saw. Slit along the mini roll with a sharp box cutter and peel off perfect rectangular flashing strips.

    3. Expert Member
      Michael Maines | | #7

      Very little moisture should be making its way to your WRB; I wouldn't worry about their detail for a second.

  4. Expert Member


    It's a close variation on how it's usually done without a rain-screen. While the consequences of water making its way through the siding aren't as serious if there is a cavity, I don't think it's a good idea to ever intentionally detail a wall to rely on draining through the rain-screen. That's also what I have against open-cladding systems.

  5. kurtgranroth | | #8

    Well, it's a unanimous consensus between Akos, Michael, and Malcom that the official JH procedure is the way to go, so I shall!

    Reflecting on this, I realize that I likely have been looking at this backwards. My thought process focused on the arbitrary nature of only some random water in the rain screen being ejected out the front and for that bit, it was less efficient than if that "ramp" hadn't been there. But I believe that that's not the right way to look at it. Who cares if the rain screen water is ejected "efficiently" as long as it is ejected?

    Instead, the relevant questions are "does this prevent water from getting into the rain screen through a butt joint?" and "does this negatively impact the rain screen?" The answer is "yes" and "no" -- it does work as butt joint flashing and it's too small and random to impact the rain screen itself. Works for me.

    And, Akos, using house wrap as flashing strips is brilliant! I was going to use cut up aluminum strips but house wrap would be MUCH easier, especially with the tongue-and-groove nature of the siding!

    1. Expert Member
      Michael Maines | | #9

      One tip, learned the hard way: in case the siding boards shrink, it's good if the flashing strip is either black or a similar color to the siding. I sided a couple of houses using shiny aluminum splines and in the right conditions they reflect light.

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