RE: [papercreters] Re: Insulation Value

Urethane insulation is particularly problematic in Arctic or sub Arctic climates for the reasons you describe.  Many houses were built using urethane foam in the Fairbanks Alaska area during the Pipeline Boom during the 70’s.  Most of them were torn down because the temperature differential was too great, inside temps in the 70 degree range and outside temps in the -70 degree range in the extreme.  These houses were sealed up so well that moisture built up in the walls and condensed in the foam near the outside surface turning to ice and gradually completely saturated till most insulation value was eliminated.  To make it worse the trapped moisture began rotting the adjacent wood framing material.

This is not as much of an issue here in Homer Alaska due to much warmer low end temperatures, but still this can be a problem as it occasionally gets below zero degrees during cold snaps.  It has been several years but temps used to get down to -20 to -30 F.   I don’t like urethane for other reasons like out gassing toxicity, fire, and cost.

Considering the double envelope FC scenario with 12” of papercrete between I am concerned about accumulating water vapor inside the shells and would like input on how to dry it out.  The fact that the structure will be buried except for windows and doors will help to moderate temperature differentials, but I still question the possible long term build up.  Properly mixed FC mortar is water proof, but not completely vapor proof.  As a precaution I’m considering perforated pipe imbedded in the papercrete that can be unplugged and forced dry air circulated through the pipes to dry the insulation.  Does anyone have input on this, like spacing of the pipes and possibly a simple way of drying the air forced through the pipes?  Does this seem like a viable solution?

Janosh

 

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From: papercreters@yahoogroups.com [mailto:papercreters@yahoogroups.com] On Behalf Of slurryguy
Sent: Friday, January 25, 2008 9:49 AM
To: papercreters@yahoogroups.com
Subject: [papercreters] Re: Insulation Value

 

The article makes a few valid points. It does an extremely poor job
of differentiating between properly installed insulation and
improperly installed insulation.

Clearly any insulation installed improperly will not perform well. I
could make a case that sheet aluminum foil is a better insulator than
improperly installed urethane foam. It proves nothing.

I don't recall anyone saying that air infiltration wasn't important.
In fact the point I have been trying to make all along is that there
are a wide variety of factors at play. Climate, insulation,
humidity, air infiltration, design of the structure, windows, and
doors are all important. Ignoring even one important factor will
lead to problems.

Grand generalizations like, (6" is enough) or (20 deg temperature
changes are required for condensation) often can lead to incorrect
conclusions.

Air infiltration is important, but not more or less important than
insulation R Factor. They both must be addressed properly for
quality construction. Other details are important beyond these two.

--- In papercreters@yahoogroups.com, "ElfNori" <elf@...> wrote:
>
> Don't agree . . . air infiltration is the thing that will suck your
heat or cool and that's the entire point of the article.
>
> ElfN
>
> ----- Original Message -----
> From: sire@...
>
> The "R Fairy Tale" article is the most ridiculous piece of
hyperbole that I have read in a long time. Eventually it devolves
into a sales pitch for u foam, and by that time the writer had lost
all credibility in my opinon.
>
> Neal
>

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