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RE: Slightly O.T.: Residential Construction - Weather-Resistant Exterior Walls

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A wallpaper that acts as a vapor barrier, especially the vinyl type, can
be a disaster in a humid climate and highly air-conditioned space,
because vapor condensate can form on the cavity side of the wallpaper.
I did an A/E liability case in Florida once, for a hotel.  The hotel was
less than a year old, with EIFS exterior and steel studs.  We could
detect absolutely no rain-water intrusion issues (though we didn't know
as much about EIFS problems back then, so who knows).  The occupants
were running AC willy-nilly, and the condensate that formed on the back
of the wallpaper turned into mildew, and where condensate formed on the
studs, caused some of them to rust through, in less than a year.  Walls
with painted finishes that had a bit of permeability had no problems
whatsoever. 

Ed Tornberg
Tornberg Consulting, LLC
503-551-4165

-----Original Message-----
From: Rand Holtham, P.E. [mailto:rand(--nospam--at)sigmaengineers.com] 
Sent: Monday, January 03, 2005 11:24 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Slightly O.T.: Residential Construction - Weather-Resistant
Exterior Walls

Bill,

Was the attic previously sealed off or did it have eave vents (or
other)? I 
don't think you'll find that Hardie recommends the omission of the
secondary 
waterproofing but if there is only moisture vapor and the roof was
always 
vented then it seems unlikely that the recent installation is the source
of 
the wallpaper failure.

Rand
----- Original Message ----- 
From: "Bill Polhemus" <bill(--nospam--at)polhemus.cc>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, January 03, 2005 11:58 AM
Subject: Slightly O.T.: Residential Construction - Weather-Resistant 
Exterior Walls


>I just want a few opinions to compare to my own.
>
> Looking at Section R703 of the 2000 International Residential Code, I 
> don't seem to be able to identify anything that would strictly define
the 
> requirements for "Hardi-Plank" siding. Typically in this area
Hardi-Plank 
> (http://www.jameshardie.com/) is used as a horizontal lap-type siding,

> over a moisture barrier or weather-resistant sheathing paper (such as 
> tar-impregnated paper, TyvekR wrap, etc.)
>
> I am not sure if Hardi-Plank CAN be installed such that it fits the 
> definition of "Horizontal Siding" as defined in R703.3.2 such that it
does 
> NOT require the weather-resistant sheathing, but my experience is that
the 
> laps are not sealed or closed (which I BELIEVE is the what is meant by

> ship-lapped).
>
> The problem is that I'm looking at a house that was re-sided using 
> Hardi-Plank, and the installer left the sheathing out during the 
> installation. There is some remaining "tar paper" still there where it

> randomly DIDN'T get ripped away during the demolition of the old 
> (composite) siding, but there are large areas left unprotected. In the

> attic area, you can actually see sunlight shining through the "cracks"

> between the Hardi-Plank boards.
>
> The installer insists that according to R703.3.2 of 2000 IRC he does
not 
> have to have the moisture barrier, because the rain is not coming
through 
> the openings. However, I just don't see it that way. The wallpaper's 
> peeling off the walls since he did his job, and the house, according
to 
> the homeowner, "feels clammy." Of course here on the Texas Gulf Coast 
> humidity is a big issue, and even in the Winter the dampness is
pervasive.
>
> Although liquid water may not be coming into the house, I suggest that

> there is a problem.
>
> Any other opinions?
>
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