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Hardie Board Installation Flashing Details

megnchris | Posted in General Questions on

Hello all – we’re nearing completion of Hardie siding installation and have major concerns with whether or not the house wrap and flashings were installed correctly.  Many, MANY stupid mistakes throughout, some aesthetic but many functional.  Concerned our warranty will be voided by the shoddy installation.  Contractor and local Hardie rep (who’s biggest customer is our contractor so biased) both agree that everything is done correctly & no reason to anticipate water intrusion, which is why we wanted Hardie in the first place.  (we’ve posted here before about our stucco woes….. ).

I’m attaching some pics that I’ve taken throughout the project.  I can’t get an unbiased, honest answer about the house wrap and flashings.  I know for a fact they did not put the flashing behind the house wrap, then tape the wrap to the flashing, which is how the Hardie instructions say to do it.  The contractor has offered to remove the plank above each window and confirm the flashing is correct, but as he pointed out, that will result in having to put lots of finishing nails in that plank.  There have been so many mistakes, we feel we can’t trust that the early steps of the process were correct.  Any advice would be greatly appreciated!!

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  1. ohioandy | | #1

    Megnchris, you've been through some painful house and contractor woes. Nobody's addressed this yet, so I'll give it a shot, with the caveat that it's super hard to diagnose and advise based on internet pics.

    A little devil's advocacy. In image 1, you are objecting to flashing that is not tucked behind the housewrap. Is it possible that there is a proper head flashing already in place BELOW this one? Windows with exterior casing can be flashed twice--the window itself is flashed, and then that assembly gets obscured by the casing and ITS flashing. Technically, only the window flashing need be tucked behind the housewrap; the casing acts like a piece of siding and so its flashing is only necessary because it doesn't have an overlap with the actual siding above it. As for the tape, that seems like a redundancy--if the flashing is properly done and sufficiently shingle-lapped, any tape is mostly theater.

    Images 2 and 3 show some truly unworkmanlike features, but aren't fatal.

    You didn't comment specifically about image 4, so I don't know what's going on there.

    Image 5: you must be sick of the staged scaffolding by now.

    1. megnchris | | #3

      Hi Andy, thanks for the reply. I'm definitely not an expert, but there is Hardie trim around the window with a flashing sitting on top of it. I honestly don't know what's under that. But, after all we've been through (and after making it abundantly clear that we want everything and anything done that can prevent water intrusion), we'd have preferred they just put it behind the wrap.

      I found what I think is another house wrap problem - in this pic the wrap is cut at the corner and doesn't wrap around. Does this need fixed? Or another crappy workmanship but not fatal flaw? Thanks!!

      1. ohioandy | | #5

        Megnchris, you say "I honestly don't know what's behind that." As I suggested to you, consider the possibility that's what's behind that is flashing done correctly. It's not necessary to embed ALL flashing details behind the housewrap--in fact, I'd argue that the continuity of housewrap is more sacred. Why make a long horizontal slit if it's not needed? Take Malcolm's advice and have the contractor remove that top piece of window casing (trim) in the presence of you and the product rep. A few nail holes to reinstall it will never be noticed.

        You also asked about the corner detail. Yes, in an ideal world with a conscientious contractor, the housewrap proceeds uninterrupted (or at least lapped) around corners. But you've got a spot repair going on here, and leaving an un-overlapped seam behind the corner trim is another one of those regrettable but not fatal decisions.

        1. megnchris | | #6

          This isn't a spot repair job though - they ripped off all of the stucco on the entire house, put on house wrap, then did full house in siding.

      2. megnchris | | #8

        Andy, I'm trying to make sure I understand the window flashing details - so in looking back at our windows before the casings are added, we do see there is flashing installed, and the Hardie trim sits on top of it. Then another flashing on top of the trim piece. Here's where I don't understand.....say water runs behind the trim flashing (b/c it isn't taped) down the wrap to the window flashing, which as you said is covered by the casing. Assuming THAT flashing is taped (or behind wrap), the water then is pushed over that flashing- but then isn't it trapped within the casing? I would think that would be a problem?? Or am I still misunderstanding?

        1. ohioandy | | #11

          Megnchris, sorry, I didn't pick up that this was the entire house. I thought it was just one wall. Yikes, to have no confidence in the entire house! So sorry for you.

          OK, have to clarify the tape thing. In this type of siding installation, one should NEVER rely on tape to shed water. The mechanical shingle-lapping of housewrap and metal/vinyl flashings should be capable of draining all bulk water to the outside. (Tape has its place--for example, the entire ZIP System--or flanged windows will be taped to the housewrap but ONLY on the sides. The top flange will be overlapped by the housewrap; tape only holds it flat and/or serves as an air barrier.)

          If the head flashing of the window is behind the housewrap, and if it has little end-dams at each side (so that water can't enter at the corners) then you've got proper flashing, tape or no tape. You have the casing nailed directly on top of this, which hopefully is elevated slightly above the flashing to leave a little channel to promote drainage and drying. Yeah, it makes a tight sandwich with the housewrap and flashing, but we're hoping that water will still find its way down and out. But, you've got ANOTHER flashing on top of the casing, preventing bulk water from even getting back there.

          How about hiring an impartial home inspector to evaluate the installation?

          1. megnchris | | #12

            Thanks Andy...yikes is right :(

            Considering the home inspector idea, though our home inspector when we purchased this house missed that none of the windows on the front wall were correctly flashed, and that the dumb-bat builder installed the end of a gutter against the house wall (see pic from 2016 attached), THEN stuccoed around the gutter, AND no kickout flashing at said gutter, so water would just run right down the wall behind the stucco. Didn't find it for 9 years...but when we did, it was just devastating. So......long story short we have trouble putting our faith in a home inspector. I have read that there are "certified master inspectors", though I suspect that the price tag for such an inspection is pretty high. Might still be worth it though?? Anyway thanks for taking a look and offering advice! They definitely did a sloppy job on the Hardie, but If it doesn't leak I'd be happy to live with sloppy. :/

  2. Expert Member


    I agree with Andy. The photos show about what I'd expect from your contractor. Not great, but nothing too worrying. They don't seem capable of stepping up their game beyond that.

    I wish y0u had convinced them to mount the siding on a rain-screen gap. The extra resiliency this adds makes poor workmanship less important.

    Considering your initial problems stemmed from, or at least were related to, window head flashing, I would get them to pull one to see how it was dealt with.

  3. megnchris | | #4

    Thanks Malcolm - yes we are particularly concerned with the windows! I wish I understood the requirements around the windows better....I find it all very confusing!

  4. woobagoobaa | | #7

    Might want to get Hardie's view on all this. I just quoted a clapboard job with several of the local Hardie preferred installers. Hardie seems pretty picky about installation requirements for warranty support. Try to get the local Hardie sales rep to inspect your job?

    1. megnchris | | #9

      Wooba - I've contacted Hardie and requested this, but I haven't heard from him yet. I actually met a Hardie sales rep virtually on FB when we were deciding between Hardie & Smartside, and he came out and looked at everything & said all is fine- BUT, our contractor is their largest customer here, so it seems there could be some bias. We just want it done right so our warranty is valid and our house doesn't leak, and it feels like we can't trust them to be truthful. One more example: Hardie requires 1.25" of overlap in plank installation (For reference the planks are 8.25" wide). In the first picture you can actually see the imprinted writing/arrow showing them where to nail. I measured in a few places where the blind nails are exposed, and they are not down the line is Hardie going to not warranty those planks? Contractor told us they would fill those blind nailhead holes with caulk and paint over them (Hardie says don't caulk any nail holes). I just don't know how picky they might be for warranty claims.

      1. Expert Member
        MALCOLM TAYLOR | | #10


        A couple of thoughts on the siding warranty:

        - I ran the general topic of product warranties by a lawyer, and his take was that for a claim to be denied, the supplier would have to show the failure to comply with installation instructions was materially connected with the product defect. They can't just pick on an unrelated omission in the installation to justify not honoring the warranty. Now keep in mind this advice comes from the much less litigious Canadian environment.

        - It is extremely unlikely that any problems you encounter will be the result of the product, not the installation. Meaning any claim would be against your contractor, not Hardi.

  5. megnchris | | #13

    Crew here today removing planks above windows and other flashed areas....none were taped to the house wrap. Also had them remove corner trim and wrap isn't continuous around the corner. Not only that but there's no wrap at all in the circled section.

    1. Expert Member
      MALCOLM TAYLOR | | #14


      Like you, I would have been working under the misapprehension that a contractor who had messed up and was remediating his poor work would be extra diligent in the repairs. I guess we were both wrong.

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