Right Nick, you post numbers but cant prove anything, because foil does
nothing of real merit to R value, it is a Radiant barrier, no R value of
significance. If as you say it increases each side by R3 then R 7.2 -
1" of polyiso would come out near R 13, kind of dumb, yes, maybe you
have numbers to prove your dream.
Unlike your arrogance, your ignorance may be curable :-)
You might buy an old copy of the ASHRAE Handbook of Fundamentals and look
at the table on R-values of plane airspaces, or look into "System R-values."
Labeling and Advertising of Home Insulation (R-Value Rule) CFR 16CFR460
(From the U.S. Government Printing Office via GPO Access)
Source: 44 FR 50242, Aug. 27, 1979, unless otherwise noted.
Sec. 460.1 What this regulation does.
This regulation deals with home insulation labels, fact sheets, ads, and
other promotional materials in or affecting commerce, as "commerce" is
defined in the Federal Trade Commission Act. If you are covered by this
regulation, breaking any of its rules is an unfair and deceptive act or
practice or an unfair method of competition under section 5 of that Act. You
can be fined heavily (up to $10,000 plus an adjustment for inflation, under
Sec. 1.98 of this chapter) each time you break a rule...
460.5 R-value tests.
R-value measures resistance to heat flow. R-values given in labels, fact
sheets, ads, or other promotional materials must be based on tests done
under the methods listed below. They were designed by the American Society
of Testing and Materials (ASTM). The test methods are:
All types of insulation except aluminum foil must be tested with ASTM C
177-85 (Reapproved 1993), "Standard Test Method for Steady-State Heat Flux
Measurements and Thermal Transmission Properties by Means of the
Guarded-Hot-Plate Apparatus;" ASTM C 236-89 (Reapproved 1993)...
The tests must be done at a mean temperature of 75 deg.Fahrenheit. The tests
must be done on the insulation material alone (excluding any airspace).
R-values ("thermal resistance") based upon heat flux measurements according
to ASTM C 177-85 (Reapproved 1993) or ASTM C 518-91 must be reported only
in accordance with the requirements and restrictions of ASTM C 1045-90,
"Standard Practice for Calculating Thermal Transmission Properties from
Steady-State Heat Flux Measurements."
Aluminum foil systems with more than one sheet must be tested with ASTM C
236-89 (Reapproved 1993) or ASTM C 976-90, which are incorporated by
reference in paragraph (a) of this section. The tests must be done at a mean
temperature of 75 deg.Fahrenheit, with a temperature differential of 30
Single sheet systems of aluminum foil must be tested with ASTM E408 or
another test method that provides comparable results. This tests the
emissivity of the foil--its power to radiate heat. To get the R-value for a
specific emissivity level, air space, and direction of heat flow, use the
tables in the most recent edition of the American Society of Heating,
Refrigerating, and Air-Conditioning Engineers' (ASHRAE) Handbook. You must
use the R-value shown for 50 deg.Fahrenheit, with a temperature differential
of 30 deg.Fahrenheit.
For insulation materials with foil facings, you must test the R-value of the
material alone (excluding any air spaces) under the methods listed in
paragraph (a) of this section. You can also determine the R-value of the
material in conjunction with an air space. You can use one of two methods to
You can test the system, with its air space, under ASTM C 236-89 (Reapproved
1993) or ASTM C 976-90, which are incorporated by reference in paragraph (a)
of this section. If you do this, you must follow the rules in paragraph (a)
of this section on temperature, aging and settled density.
You can add up the tested R-value of the material and the R-value of the air
space. To get the R-value for the air space, you must follow the rules in
paragraph (c) of this section.
For aluminum foil: the number of foil sheets; the number and thickness of
the air spaces; and the R-value provided by that system when the direction
of heat flow is up, down, and horizontal.
For insulation materials with foil facings, you must follow the rule that
applies to the material itself. For example, if you manufacture boardstock
with a foil facing, follow paragraph (b)(4) of this section. You can also
show the R-value of the insulation when it is installed in conjunction with
an air space. This is its "system R-value." If you do this, you must clearly
and conspicuously state the conditions under which the system R-value can be
Wake up senile nick, R value is R value, a standardised measurement used
to measure insulations effectiveness, resistance to heat flow. Polyiso
foilfaced, Both Sides is R 7.2" new, 6.8R" stabilised. Your mythical
dreamworld of R 6 added with 2 sheets of foil does not exist anywhere in
reality or at any store on this planet, or it would be sold as R 12.8*
polyiso, and it is not.
Senile is not the word.
Nick appears to believe that he is a reincarnation of a mythical
all-knowing, all-powerful being. His attitude towards others reinforces
this idea with almost everything he posts.
patent holders are idiots.
Facts are false.
Everyone else besides Nick are absolute morons is the message he conveys
Aluminum foil is tested for 'emissivity' not R value. That is the test
is to see how good a RADIATOR it is not how good and INSULATOR it is.
If it is used for cookware and electric power distribution, it CAN'T be
an insulator of heat or electricity.
Aluminum is therefore a RADIANT barrier, and may also act as a vapor
retarder, but it does NOT improve an INSULATION material's ability to
restrict the movement of heat, EXCEPT by REFLECTING the heat - but it
RADIATES to BOTH sides of the foil.
An AIRSPACE MUST be incorporated in order for the foil to be effective
and the literature that Nick quotes indicates this as well.
So Foil helps, BUT only when there is a air gap. Foil faced insulation
is more effective than non foil faced insulation only when there is an
air gap for the foil to radiate heat into. Even then, if there is no
circulation of that air, we get a heat buildup between the foil and the
outside sheathing that could take most of the night to dissipate.
It can work that way in the real world, but it's illegal to advertise R12.8,
according to US federal regs, because the R-value depends on the installation
conditions, which is confusing to the general public. Altho we can measure and
calculate and advertise the "system R-value," if we have the merest grasp of
R is the fraction of heat loss compared to an air gap the same thickness.
So R-19 insulation will conduct 1/19 as much heat as an air gap the same
thickness. If you place two pieces of insulation on top of each other you
can add the R value. For example two 6" fiberglass bats (R-19 each) equals
We're talking two different strategies for insulating a crawl space
here, I believe. You intended to put fiberglas batts between the
floor joists, and he wants you to insulate the walls of the
The difference is how the crawlspace functions. In your system, it
stays close to the temperature (and humidity) of the outside air.
You open the small vent windows in the summer and block them off in
the winter. In his system, the crawlspace is insulated space --
warmer in the winter and colder in the summer. The crawlspace
isn't ventilated at all in any season.
So it seems to me you and he are talking apples and oranges. Both
methods are routinely used these days. You might want to talk to
your local utility and get their recommendation for what works well
in your area -- and, if you seal the crawlspace, how to deal with
heating equipment in the crawlspace (needs an intake air duct for
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