Specification
THERMAL PERFORMANCE
Air infiltration can account for over 50% of the
heating and cooling energy loss through the
walls of a home. Thermo-ply
®
provides supe-
rior protection against air infiltration because
when fastened to the framing and studs, its
inherent thickness provides the tightest seal of
any sheathing material on the market. Cracks
and gaps are minimized for air to infiltrate,
resulting in improved energy efficiency and
lower utility bills.
*Calculations show that
just a
1
/16” gap around
the perimeter of an av-
erage home can waste
5 times more energy
than can be saved by
two inches of additional
insulation to the walls
of a normally insulated
home.
The Importance of Controlling Air Infiltration
EFFECTIVE R-VALUE IS WHAT COUNTS
Insulative foam sheathings promote their initial high R-value. How much of that R-value is actually
retained after it has been installed? Several factors can significantly impact its true performance.
• Foam sheathings age over time and can lose their original R-value. It’s important to
r e fe r t o a g e d R - va l u e d a t a i n m a n u fa c tu r e r ’s
literature.
• Foam sheathings are fragile and can easily be damaged at
the job site by high winds and handling, creating holes and
broken corners for air to penetrate if gone unrepaired.
• Foam sheathings are “spongy like” and are difficult to fasten
tightly to the wall frame creating gaps for costly air infiltration
to penetrate the wall cavity.
• Foam sheathings are non-structural which creates the need
for structural bracings. Consequently, when plywood or OSB
is used at the corners of the home, the exterior wall cannot
“truly” claim the entire added R-value it gets from the foam sheathing when it is only used in the
intermediate areas. Plywood and OSB have an R-value of less than 1.
• Fasteners (nails or staples) used to attach foam sheathing to the stud wall creates an effect called
“thermal bridging” which can also reduce the sheathing’s original R-value by up to 20%!
1
“ Higher R-values and insulation belong in the wall cavity
between the studs”
...PROTECT IT WITH THERMO-PLY WALL SHEATHING
1
(“Energy Focus” article, September 1993 - Toledo Homebuilding Magazine)
*Dow Styrofoam is a registered trademark of Dow Chemical Inc.
No
Gap
Small
Gap