R-Value
Thermal Performance Myth.
There is a widespread belief that all
insulation materials of equal R-value will
perform equally.
Thermal Performance Fact.
While insulations of equal R-value perform
equally in the controlled conditions of a
laboratory, they do not all maintain that
R-value in the walls and ceilings of a
building. Some give off gasses to the
atmosphere and suffer a decline in
efficiency, while the performance of others
are vulnerable to the installers'
shortcomings.
'Thermal Drift' as this phenomenon is politely
called, results from the failure of materials to
fill all cavities completely, thus leaving air
pockets which permit air movement inside the
cavity. Further 'drift' occurs with some
materials if the insulation is not fully
protected against air infiltration, both from
the interior and the exterior. Commonly used
insulation may well perform at a fraction of
its' nominal rating depending on installation,
how well it fits the cavity and how well it's
protected from air infiltration.
The performance of The Spray Foam Insulation
System does not 'drift.' It is not dependent on
the installer, or on other trades. As it
expands, the material forces its way into every
corner and crevice, completely filling the
cavity. It creates its own virtually continuous
air barrier by adhering to structural
components. It always ensures a well filled, air
sealed building envelope. It contains no
gasses, so none escape.
Blower door tests
have proven that foam, with no polyethylene
vapor barrier, can make a steel framed home as
tight as 1.2 ACH @ -50 Pa. depressurization,
which is equivalent to 0.03 natural air changes
per hour, when required.
Click
here to
return to Building Science.
