No underlayment or WRB under Hardiplank

Ok, so I understand a WRB is not required behind concrete or masonry walls with a proper flashing, but does that include Hardiplank siding? The side gables on a house I inspected today had the Hardiplank nailed directly to the framing studs. Is this something new I’ve missed? I believe there should be some form of WRB between the studs and the Hardiplank.

Hardi-Plank.pdf (15.6 MB)

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You sure it is Hardiplank? If your not sure, then it is cement fiber lap siding. :smile:

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Hey Martin, Thanks for the info; I’ll add it to my library

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Hey Brian, good point. I’ll adjust my verbiage.

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In my experience, it is seldom installed correctly. Clearance issues, flashing, fasteners, joint treatment etc. Which is silly, because the quick install guide is printed right on the wrap when it is delivered to the job-site in a few languages.

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That’s no joke. I watch siding crews install various brands almost daily. Slap it up and go… I’ve even seen it installed backwards. LOL…

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Definitely needs a WRB- Building (Felt) Paper / House Wrap. That may not be specified by Siding manufacturers installation instructions since that should already be there before siding installation but it is certainly a code requirement.

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I’ve always heard part of the issue with Hardi has been the changing installation instructions. Nevermind what other fiber cement siding manufacturers call for.

Yes, they do change. I check for updates almost every time I do new construction inspections. Most of the other manufacturers follow Hardi almost to the letter.

In new construction, I look for a few key things and go deeper if they really start screwing up.

  1. Clearance issues.
  2. Horizontal flashing and kick-out flashing
  3. Butt treatment (caulk, flashing or H-clips)
  4. Over driven fasteners.