Roxul ComfortBatt - Manual (Page 6)

6
Better | Best
Effective R-values versus Nominal R-values
People are often surprised at the difference
between the commonly stated (nominal) R-value
of insulation and the effective R-value of the
insulation within the wall assembly. This reflects
the difference between controlled lab tests
versus the real-world performance.
Although the insulation package may state a nominal
R-13, the effective R-value of the assembly may be
smaller. This reduction is dependent on the thermal
bridging of the structural elements that bypass the
insulation. Thermal bridging is where heat escapes
through a conductive material that creates a bridge
between the outside and inside causing heat loss.
For example, wood studs conduct heat relatively
well as compared to insulation. Steel studs conduct
thermal energy extremely efficiently, thereby reducing
the effectiveness of the wall assembly to resist the
loss of heat. High-density stone wool insulation
resists heat loss better and achieves better energy
performance than fiberglass insulation, which is
less dense and less stable.
Today’s building codes are moving to mandate
effective R-values over nominal R-values – and
ROXUL
® stone wool, because of its higher density
and dimensional stability, leads the way as the
interior and exterior insulation of choice for
residential applications.
Decreased thermal bridging equals
a better performing wall
ROXUL insulation helps reduce thermal bridging
through wood studs, leading to a better performing
thermal wall. In a typical single-family building,
wood studs make up 25% of the wall surface, so it’s
important to ensure the use of exterior insulation
to complete the building envelope.
Factors that contribute to
superior thermal performance
With informed consumers and the building industry
pushing for innovative solutions that are truly
energy efficient, ROXUL raises the bar in developing
wall systems with excellent long-term thermal
performance. This is the result of two inherent
properties in its insulating systems – lack of thermal
loss due to dimensional changes, and the insulation’s
ability to repel water, which aids in the control of
heat loss and gain.
The use of ROXUL stone wool as a continuous insulation
(c.i.) also contributes to a building envelope's efficiency,
giving it higher effective thermal resistance values
than foam plastics.
Made from stone wool, an inorganic combination
of basalt and recycled slag, ROXUL insulation is
thermally stable, maintaining its R-value over time.
The insulation will not expand or contract due to
humidity or temperature variance.
What is
R-value
?
R-value is a unit of measure describing the resistance of heat flow through a material (e.g. insulation, stud, wallboard)
or a wall assembly. Generally, the higher the R-value, the better the material/assembly is at reducing heat loss
(or heat gain). Many factors play a role in this transfer of heat, including the structural components that bypass
the insulation, as well as humidity and variance of fluctuating daily temperatures.