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Jeff[_7_]

GregS wrote:
In article , (GregS) wrote:
In article , krw
wrote:
In article ,
says...
In article , krw
wrote:
In article ,
says...
In article , krw
wrote:
In article ,
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On Tue, 8 Jul 2008 22:50:07 -0400, "JonquilJan"
wrote:

There was one home about half a mile from me - where it was tried to
insulate. Once they took off the outer shell, there was a frame of
very
large hand hewn (could see the ax marks) beans - filled in with
bricks
and
mortar between.
Everything in my house was hand hewn. The home inspector who did the
report
before I bought the place thought the joists weren't real wood because
they
were "misshapen and just way too big" (his words). When I pointed out
that
the house was nearly 200 years old, he then assumed that the wood
would
be
rotten. He was extremely surprised that everything in the house was
just
fine. He commented that the house was "better built than anything
they're
making now". Well, yeah, since my house was built to last, not to
current
"code". 24" on center. Are they crazy? Everything in my house is
12-15"
on
center, and 4x4, not 2x4. Hardwood floors over diagonally laid tongue
and
groove subfloor over wide plank pine. An elephant could jump up and
down
on
my floors and you'd never feel it. I would never live in a "new"
house.
I would bet that a "properly built" house today will use a lot less
heat than yours. 2x6s 24" on center construction is certainly
better than 2x4s on 16" centers, and even somewhat better than 2x6s
16" on center. Wood is a pretty poor insulator.

1 inch of dry wood = R1.
Yes, pretty damned poor.

2 inches = R2
Rather obvious.
Put a reflective surface on that and you can add 1.5. Sometimes a reflective
surface can be much more than R 1.5 depending if there are really hot
areas involved, or high differentials.
Not that it has anything to do with the issue at hand, but this is
simply wrong. The reflective barrier will not keep heat in; zero R
value. It will *reflect* IR radiation and is useful in areas with
lots of sun, but it adds zero to the R value.

Tell that to the people who label their foam products at the home stores.
The reflective factor is added to the R value.
The reflective surface also inhibits radiation as well as reflecting radiation.

A reflective surface needs open space for it to reflect. If there is no space
its worthless.

Yes, It also depends on the mounting direction and direction of heat
flow, that is part of the convective loss.

You will always have radiative heat transfer, if you have a temperature
difference between the surface and ambient temperatures and some
emissivity of the surface. Lowering the emissivity lowers the loss,
shiny = low e. That's why good windows have a low e coating.

So, you have three methods that heat can be transferred: conductive
(which is the only R that krw understands), convective and radiative.

Lets look at convective losses for a moment as they have a lot to do
with R values. That's why although air is a much better insulator than
wood, that 6" of wood is R6 and 6" of air is only about R1. It's the
convective air currents and is why breaking up the air space with
fiberglass strands increases the effective R value.

Jeff

On a building here, they specified foil backed drywall
for RF interference. This is also mold proof, and I don't know why its not
usually seen at the home buiding stores, and of course can add some
R value if used in that way.

greg