krw wrote:

If you read back, I said that foild will help by REFLECTING radiated
heat. It doesn't do squat for the 'R' value, however, because that
is a measure of CONDUCTED heat.

No. R-values are measured, and they include all forms of heatflow.

Your definition of "R-value" is meaningless. The 'R' varies by
application, which makes it a meaningless number.

You've made a mistake, Keith. I suggest you admit it and move on.

Nick

In article ,
says...
krw wrote:

If you read back, I said that foild will help by REFLECTING radiated
heat. It doesn't do squat for the 'R' value, however, because that
is a measure of CONDUCTED heat.

No. R-values are measured, and they include all forms of heatflow.

Your definition of "R-value" is meaningless. The 'R' varies by
application, which makes it a meaningless number.

You've made a mistake, Keith. I suggest you admit it and move on.

Wrong again. R-value is not dependent on how bright the sun is.

--
Keith

krw wrote:

... R-value is not dependent on how bright the sun is.

Who said it was? :-)

Nick

In article , krw wrote:
In article ,
says...
krw wrote:

... 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.

Wrong.

Not wrong. Foil does nothing to "resist" the conduction of heat
therefor has no "R" value. It will REFLECT radiated heat, but do
ZERO for conducted heat.

With an air gap, the foil adds a real R-value.

Nonsense. The air gap adds R-value. The foil adds nothing to the
heat conduction. Foils is METAL, which is a CONDUCTOR.

Regardless of the technicalities of wording, reflective barriers
are extremely important when the R value is low.

I experimented with some 3/16 inch Polyethelene foam with reflective
barrier on both sides. In my basement on the cinderblock, which is R 3.5,
I laid down a sheet against the block. I added another layer on the 3 inch
wood framing members. Measuring the temperature differentials was very
remarkable. Better than I could have imagined. It compared very favorable
with the 3 inches of fiberglass on other areas. I was thinking, and may still do,
add preforated foil on top the insulation in the attic.

greg

In article , wrote:
krw wrote:

If you read back, I said that foild will help by REFLECTING radiated
heat. It doesn't do squat for the 'R' value, however, because that
is a measure of CONDUCTED heat.

No. R-values are measured, and they include all forms of heatflow.

Nick

I looked very closely at the foam sheeting at the home building center.
The R value is definately added with the foil backed foams. What
they don't say, there must also be that air space in order to perform
reflection and low emmision.

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 ,
says...
wrote in message
...
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

In article , (Nick Pine) wrote:
GregS wrote:

I looked very closely at the foam sheeting at the home building center.
The R value is definately added with the foil backed foams.

What would lead you to believe that? The FTC says that's illegal.o

Polyisocyanurate often has foil, unlike Styrofoam, but its bulk R-value is
higher and the foil helps the foam avoid outgassing which lowers the R-value.

Nick

You could be right. I was assuming all the foams have similar R value.
I think I was also looking at the ratings of say, 1 inch compared to two inches.
If the reflective value is there, two inches will not be twice the R of 1 inch.

greg

GregS wrote:

I looked very closely at the foam sheeting at the home building center.
The R value is definately added with the foil backed foams.

What would lead you to believe that? The FTC says that's illegal.o

Polyisocyanurate often has foil, unlike Styrofoam, but its bulk R-value is
higher and the foil helps the foam avoid outgassing which lowers the R-value.

Nick

In article ,
says...
In article , krw wrote:
In article ,
says...
krw wrote:

... 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.

Wrong.

Not wrong. Foil does nothing to "resist" the conduction of heat
therefor has no "R" value. It will REFLECT radiated heat, but do
ZERO for conducted heat.

With an air gap, the foil adds a real R-value.

Nonsense. The air gap adds R-value. The foil adds nothing to the
heat conduction. Foils is METAL, which is a CONDUCTOR.

Regardless of the technicalities of wording, reflective barriers
are extremely important when the R value is low.

I guess a penny is important when you're broke.

I experimented with some 3/16 inch Polyethelene foam with reflective
barrier on both sides. In my basement on the cinderblock, which is R 3.5,
I laid down a sheet against the block. I added another layer on the 3 inch
wood framing members. Measuring the temperature differentials was very
remarkable. Better than I could have imagined. It compared very favorable
with the 3 inches of fiberglass on other areas. I was thinking, and may still do,
add preforated foil on top the insulation in the attic.

You don't go into much detail, but your experiment is likely flawed.
The foil is doing nothing. The foil *might* do some good in the
attic for reasons I've mentioned.

--
Keith

In article , krw wrote:
In article ,
says...
In article , krw
wrote:
In article ,
says...
krw wrote:

... 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.

Wrong.

Not wrong. Foil does nothing to "resist" the conduction of heat
therefor has no "R" value. It will REFLECT radiated heat, but do
ZERO for conducted heat.

With an air gap, the foil adds a real R-value.

Nonsense. The air gap adds R-value. The foil adds nothing to the
heat conduction. Foils is METAL, which is a CONDUCTOR.

Regardless of the technicalities of wording, reflective barriers
are extremely important when the R value is low.

I guess a penny is important when you're broke.

I experimented with some 3/16 inch Polyethelene foam with reflective
barrier on both sides. In my basement on the cinderblock, which is R 3.5,
I laid down a sheet against the block. I added another layer on the 3 inch
wood framing members. Measuring the temperature differentials was very
remarkable. Better than I could have imagined. It compared very favorable
with the 3 inches of fiberglass on other areas. I was thinking, and may still
do,
add preforated foil on top the insulation in the attic.

You don't go into much detail, but your experiment is likely flawed.
The foil is doing nothing. The foil *might* do some good in the
attic for reasons I've mentioned.

If it didn't work I would redo it. This area is about1/6 of the basement.
The reason I began trying this stuff is because its the only foam you can use
without protective drywall covering it. The preforated foil also has a polyethelene
center. It does wonders in the garage with only the thin sheet, forming one additional air
space I could not stand in the garage summers before. You could feel the heat
radiating from the ceiling. Now there is NONE.

greg