Wh ere is the best
placement for a radiant barrier? Radiant barrier, cellulose, home, energy,
fiberglass, radiant barrier, attic insulation, energy conservation, green
Where Should Radiant Barrier Be
Fact: Radiant barriers are not rated using
the R factor. Radiant barriers are measured by reflectivity and
Fact: Radiant barrier was not invented by NASA, it
was invented by Sir James Dewar, a Scottish physicist who invented the
Thermos Bottle among other things.
Fact: Lowering the emissivity of a surface
(which is one aspect of a radiant barrier), can have negative consequences, as
in making your home use more power and become more
uncomfortable if installed incorrectly.
Reality: Radiant heat is not just from the sun,
radiant heat is everywhere and is the fastest way heat enters your home during
the summer and contributes to large losses during the winter.
Many radiant barrier systems (RBS), are designed to be
placed at the roof to either reflect radiant heat or lower the emissivity from
bare wood at .95 to something lower. Many
things happen (and this only true on attics with a pitched roof. On a
flat roof it's not an issue because there is no convection). And the steeper
the roof, the more convection:
INSTALLED UNDER THE
This application has absolutely no benefit during
the winter, despite how mild your winters are. Would it not make sense
to purchase and install a product to control heat gain and heat
loss? This way your investment pays off all year and increases comfort
Lowering the emissivity of a roof decking the
attic with silver paint, laminated foil, or stapling a radiant
barrier up under the roof decking raises the temperature of the
surface above it, that's just basic physics and common sense. If radiant
heat is restricted from emitting from a surface (as in the bottom of your roof
decking, a chrome car bumper or a chrome socket in your toolbox), heated
by the sun, where does this heat go? With lower emissivity it's
going to increase the roof temperature and have to radiate back out...one
problem: the sun is beating on it at the same time. Is that going make
your roof hotter? Of course it is. Is this going to extend the
life of your roofing system? (shingles or on tile roofs, the
underlayment?). I'm not going to leave myself open telling you my
experiences so let me tell you what the largest shingle manufacturer told me
during a recent phone call: (question) "Yes, I have a question.
Will installing a radiant barrier under the roof affect the warranty of your
product?" (answer) "Our 25 year warranty covers manufacturers
defects". When pressed for an answer regarding the installation of
a radiant barrier and elevated roof temperatures I was again told:
"Our warranty only covers manufacturers defects, that's all
I'm going to say, good bye". It seems I'm not the only one afraid to
touch on this topic so that leaves the reader on his/her own to decide if
increasing the roof temperature is going to lessen the life of the roofing system
by making it hotter and drying it out. This really becomes a problem
with concrete tile roofs that rely on a thin piece of bitumen based (tar),
felt (paper), to keep the ceiling dry. When this dries out and curls up,
all the tile has to come off, all the wood strips, all the underlayment, and
be replaced. Homes around here are having to have it done at the tune of
$8,000 to $12,000 which is mostly labor. Think twice
before spraying paint under your roof, buying foil backed OSB or
stapling a reflective membrane up under the roof deck. The last
thing you want to do is make your roofing material hotter.
If increasing the roof deck temperature
when lowering the emissivity under the roof increases roof
temperature, how is this going to affect the air in the attic that
is in direct contact with this hotter roof? Stands to reason if the roof
deck is hotter, the attic air is going to get hotter from the
increased convective air movement from the hotter roof deck. If the
air in the attic is getting hotter via convection from the hotter
roof, wont this in turn make the insulation hotter and the
ducting in the attic hotter? Hotter than a house
without RBS on the bottom of roof deck?
Basic physics and the laws of thermodynamics guarantees it
will and the graph below illustrates it.
Next question: If the attic insulation gets
hotter than an attic with bare wood, what happens when the
sun goes down, and the roof cools off? What is this superheated insulation
now facing? A reflective radiant barrier. A radiant
barrier which now effectively holds the heat in the attic for hours after
the sun goes down. (again, see the graph below).
We would rather see the RBS right above the
insulation, keeping heat out
during the summer
and heat in during the winter. This also does not affect
roof temperature as the emissivity of the roof has stayed the same. The
reason radiant barrier is stapled up against the roof is because of eventual losses
due the accumulation of dust which virtually negates the
performance it once had.
Covering the ducting in the attic with RBS is also
another significant energy conservation method. Click here to see our duct wrap
Fact: Dust is a major problem
with RBS rolled out over the attic insulation. This is why our
Membrane has multiple layers to deal with
this problem. It's also proven, patented and once installed,
will change the way your home feels forever. TCM is the only
radiant barrier with a lifetime performance warranty. Before buying any
radiant barrier or reflective insulation product ask about a performance
More facts: Insulation
has a tremendous potential for storing
heat. Insulation resists heat loss (R
factor). Here's a good question: If you are outside in
January at night, would you put a sweater on? Question #2: Do
you wear sweaters in August when you working out in the yard? In the
sun??? And your home has walls and ceilings packed with
sweaters? To keep the heat out????
We have developed innovative, proven methods that far
exceed the performance of conventional insulation products. Read on and
become enlightened and once aware of what the alternatives are, you can make
better decisions on obtaining comfort for less cost.
Before you spend
your energy conservation dollars on anything, especially a radiant barrier
product, do some research, follow the logical path and ask a lot of
questions. Specifically, ask for a lifetime performance warranty and
RBS placement in the
attic is very important
In the summer of 1993 an Arizona
electric utility began testing the performance of three types of Radiant Barrier
Systems (RBS) in three different placements in four identical unoccupied homes.
One home was a control house with no RBS. Data collection included time,
temperature and measurement of power usage. All power was shut off in these
homes except for the heat pump. The results of this testing brought to light
some interesting data as shown below.
product, RBS Chips, is outlined in green. RBS Chips was our
first patent on reflective insulation which led to the creation
of Thermal Control Membrane. Had the house with the green line
been Thermal Control Membrane the green line would be
significantly lower all day.
The graph above illustrates some interesting points: First,
notice the banner that was printed across
the page: "Test results are
inconsistent with Engineering calculations and must be verified before
accepted as factual. The graph tells it all. This is
not an "engineered calculation" from a test
box but actual
unoccupied 2100sq foot homes with tile roofs. The only breaker turned on
in the main
panel is the heat pump. This graph is a snapshot of one
24hr period. This test on full size homes
went on for
UNDER THE ROOF DECKING
radiant barrier directly under the roof decking as illustrated above
raises the attic temperature (and energy consumption), between 2pm and
8pm. The reason is simple, when the inside roof deck
is lowered from
.95 (bare wood), to a lower value the result is a hotter substrate hence the
logic behind the radiant barrier. This is a perfect application for
a flat or nearly flat roof deck. The reason being, the increased
temperature of the roof deck will not create convective movement since the roof
is not pitched. The steeper the roof, the more convection there will
be which in turn heats up the attic insulation and once the sun goes down,
the elevated attic insulation is now facing the radiant barrier on the
bottom of the roof. Again, this only applies to
pitched roofs. Spraying a roof silver underneath the roof deck or using a plywood decking product with a
radiant barrier laminated
to it as can be
seen above is an improper installation, especially if the attic is vented to
standard venting code.
climates: Our perforated Thermal Control Membrane is rolled
out over your existing insulation. This will keep heat in your
home and prevent ice dams. It's also very effective at increasing comfort
during the summer
Hot Climates: Roll our proven Thermal Control Membrane over your
existing insulation. Radiant barrier stapled up against the roof will
increase your roof deck temperature, accelerate the degradation of your tile
underlayment membrane and/or shingles and has no effect on cold winter
WALLS: Heating Dominant Climates (cold
RBS sheeting should be placed between the interior sheet rock and wall insulation.
This will act as a vapor barrier as well as a radiant barrier, all seams must be
taped. IMPORTANT! Do not place a non
permeable membrane of any type between the wall insulation and the outside wall.
Water may condense on the film creating all kinds of problems including but not
limited to: wood rot, mildew, ruined insulation and unwanted critters.
Dominant Climates (mild winters, hot summers)In climates where
the night temperatures rarely gets below freezing, our Thermal Control
Membrane can be placed on the outside of
the exterior sheathing and finished wall system (stucco, brick, siding,
plywood). Remember to create an airspace to the exterior finished wall does
not contact the RBS sheeting, this will create a path of conduction and negate
the performance of the RBS. Some products that work well for this
- 1/4" redwood lath strips
- 3/4" pine fir ring strips
- Steel hat channel
Apply the RBS to the exterior first, then secure our patented "Diamondback Wall System",
or use fir ring strips of choice on
16" centers. Attach the exterior wall to the strips. See photo below
TCM applied in a hot
climate on an exterior wall which will be re-stuccoed. In cold
climates, install on the inside just behind the sheet rock and tape the seams.
Our latest product, "Diamondback Stucco Foam", is now
available. Our patented design eliminates
the need for fir ring strips (
which adds $1800 in extra costs to a 2000 sq foot home), saves
and is much more efficient when building with a stucco wall
system. See picture and link below for
here for more information on this exciting new
sustainable building product.
Building a new home? Adding a room? Drop us email anytime if you have questions
about how to
make your new home or addition super energy efficient and
Thermal Control Membrane is easily installed between the
trusses in the attic. Think of it as a flexible
Thermos Bottle...keeps heat out in
the summer and heat in during the winter.
Visit our online store!
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front door! Free shipping!
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