Myth#5 Under the hot sun, a black shingle roof could easily exceed 150°F surface temperature and as the heat conducts through the roof
deck, the interior roof deck surface might be close to 140°F. This
heated surface acts like the heating element in your toaster and
radiates heat into the attic heating the air up to 120°F.
By installing spray foam insulation to the underside of the
roof deck, just like turning off your toaster, you change the
temperature of the interior radiant surface. The new radiant
surface is the exposed surface of the spray foam and rather
than being 140°F, like the exposed roof deck, it will be closer to
the interior conditioned temperature, around 80 to 90°F, thus
having a tremendous effect on radiant heat transfer.
Overall spray polyurethane foam can address all three forms of
1. Conduction, of course, with its tested and documented
K-Factor and R-value;
2. Convection because of its air barrier qualities;
3. And, radiation because the temperature of the exposed
radiating surface is significantly lowered.
This is why spray foam outperforms other insulation materials,
not because of some magic “effective R-value,” but because
spray foam can fundamentally and scientifically have an impact
on all three forms of heat transfer.
Immediately after that, another attendee says, “But if spray
foam works so well, can’t you make the house too tight? I mean,
doesn’t the house need to breathe?”
HOUSES NEED TO BREATHE
No, your house does not need to breathe. It
does not have lungs. The people in the house are the ones that
need to breathe.
Even if houses needed to breathe, that’s not a very good
justification to build leaky, drafty, inefficient buildings.
For energy efficiency and interior comfort purposes, the best
approach is to seal the structure as tight as possible, then take
care of the indoor air from the inside out, with a proper air
management system. After sizing the mechanical system, there
are several options for providing fresh air ventilation that range
from a simple damper controlled inlet duct that is installed on
the return side of the HVAC system, all the way to the high-end
energy recovery ventilator, which will condition the supplied air
using energy from the exhaust air.
The best building science has to offer is, “Build it tight and
Finally, right before lunch, you get the granddaddy of them all,
possibly the biggest, most misunderstood idea when it comes
to spray foam insulation, “I love foam, but this stuff is too
SPRAY FOAM IS TOO EXPENSIVE
WOW, this is a shortsighted point of view.
Yes, when installed , spray foam is going to cost more than
traditional insulation upfront.
Guess what, a high-performance machine always does!
But the standard payback period, for both open-cell and closed-cell foam, in all climate zones, is less than five years. That’s more
than a 20 percent ROI.
Where else are you making 20 percent on your money?
Also, even if the spray foam upgrade costs an additional
$10,000, when financed over 30 years, that adds less than $50 to
the monthly payment, and with a typical energy savings that can
be $100, $200, or more per month, the homeowner is in positive
cash flow from day one.
Finally, for you cash buyers that don’t care about payback,
ROI, or positive cash flow compared to financing costs, when
mechanical systems are properly sized and designed, based
on the building envelope package, using spray foam insulation
can reduce the size of the mechanical system, which means the
mechanical system may cost less upfront.
With these concepts in mind, traditional insulation will cost you
more in the long run, so if you ask me, it is too expensive not to
use spray foam.
The point is that spray foam is the only upgrade that will not
only pay for itself, but it can also buy granite counter tops.
Is this possible? While working a simple tradeshow you get
questions about five spray foam myths, all before lunch.
It has happened to me; it can happen to you.
Robert Naini has a Bachelor’s of Science in
Mechanical Engineering and an MBA from the
University of Texas at Arlington. With more
than twelve years of experience on the cutting
edge of spray foam insulation, he has developed
a unique knowledge base including spray foam
sales & marketing, employee & applicator training,
building science awareness and building code expertise.
Leveraging his spray foam knowledge and business know-how,
Robert has helped both manufacturers and contractors grow
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