[Greenbuilding] vented roofs

[Laren Corie]

"Janet L. Hobbs" <janethobbs at hobbsink.com>

>  I have heard but not verified that some shingle manufacturers won't
> warranty their product if it isn't ventilated.

Hi Janet;

  That is true;

 They say that heat is the reason for the invalidation of the guarantee 
However, it is very interesting that testing shows that darker shingles,
over vented attics, consistently run much hotter than lighter colored
shingles with no venting.  That reason is not logical.

So, there must be more at play here, than is first apparent.

1) The big shingle companies that set the standards, 
are also the major fiberglass insulation manufacturers.
2) The unvented roof insulations are the same insulations
(cellulose and foams) that are major competition to fiberglass.
(if 8-9%, in the US, can really be called major competition)
3) The fiberglass industry has an extremely well organized
program to dis-educate the public against alternatives.  Just
Google "cellulose insulation" then look whose pages come up,
and how most of them use identical extremely well written,
but even more deceptive, text from their insulation manufac-
-turers association, that only allows fiberglass manufacturers.

   The limit on the warrantee is a very clever way to get two
advantages at once  They can both get out of their guarantee,
while screwing up a good sale for their insulation competition.
Cellulose is, by far, the main competition. Vented cathedral
ceilings with cellulose are generally too much bother to be
cost effective.

That seems to be the only understanding that makes full sense.
If anyone has contrary information, please present it.  I would
hate to be seeing evil, where it does not exist, but nothing else
seems to be logical, in this case.  Their fiberglass industries'
cellulose websites are definitely in a category that I consider
immorally deceptive.  They have some very good writers,
who could convince you to stop breathing to avoid
second hand smoke in the middle of Antarctica,

-Laren Corie-
Natural Solar Building Design Since 1975
www.LarenCorie.com

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