A BRIEF ON POLYCARBONATE FACADES AND PTFE

1. PLASTIC FAÇADE
SYSTEMS
Compiled by Revathy Royer
B.Arch (ID)
7th sem
POLYCARBONATE
PTFE (Teflon)

2. POLYCARBONATE FAÇADE SYSTEMS

3. INTRODUCTION :Polycarbonate
panels are used mainly for facade
glazing and cladding, as an
alternative to glass or GRP (glass
reinforced plastic) curtain walling and
cladding, as well as conventional
rain-screen systems. They can also
be used for roofing, canopies and
interior design elements.
Polycarbonate is a type of
thermoplastic — that is, a polymer
that becomes pliable or moldable
above a specific temperature and
returns to a solid state upon cooling.
Polycarbonate falls under
“engineering thermoplastics”.
These are grouped together
because of specific properties that
allow them to be used in rigorous
applications, particularly in the
electronics, automotive, construction
and manufacturing fields.

4. Polycarbonate provides a number of advantages when used for glazing.
• Aesthetics Polycarbonate panels come
in a range of colors and degrees of
translucency. Blocks of colored panels
can be arranged into patterns and
illuminated facades can be created by
combining translucent panels with LED
or ambient lighting systems. As a
thermoplastic, polycarbonate can also be
molded into curved panels to create
bespoke facade treatments.
• Thermal performance Trans-lucent
polycarbonate wall panels can be
manufactured with U-values of 0.71-0.77
W/m2K as a single-wall construction and
0.36-0.43 W/m2K as a double-wall
construction. These panels can be used to
allow natural daylight to enter a building
without compromising its thermal efficiency.
Light transmission through translucent
panels can be up to 65%.

5. • Weight Polycarbonate panels are lighter than glass or solid wall systems, so require
lighter support structures, which can help to reduce costs.
• Strength : Polycarbonate has excellent impact properties and are up to 200 times
stronger than glass. Polycarbonate elements do not crumble or splinter.
• Weather resistance: Polycarbonate panels have been tested for air and water
permeability, including a simulated hailstorm test at Swiss testing laboratory EMPA.
• Solar resistance : Ultraviolet filters can be extruded into the polycarbonate, reducing
solar gain without blocking natural daylight or the need for a separate film over the
panel.
• Fire resistance : Polycarbonate has a very high ignition temperature of about 450ÞC
and, in case of fire, produces very little smoke.
• Acoustic protection Despite their light weight, polycarbonate elements have a good
sound insulation value of up to 27dB .With a double-wall construction, a value of up to
43dB is achievable.

6. INSTALLING A POLYCARBONATE WINDOW WALL SYSTEM
A typical wall system will use a framing system that is
both air- and watertight. This will be composed of
perimeter aluminium channels with head, base, side
and corner sections and front and rear thermoplastic
elastomer gaskets. This framing is fixed to the
structure and can be supplied mill-finished, anodised
or polyester powder-coated to any RAL colour.
front-wall
installation installation in
embrasure
with
weatherboard
installation
in
embrasure
without
weatherbo
ard

7. The translucent building elements are delivered — depending on the finish — with one-sided or
both-sided protective foil. This film must be kept on throughout installation.
bracing bottom profile corner profile
Panel ends are sealed with a
combination of aluminium/
butyl tape and vent tape to
prevent water, insects, gases
and other fine particles from
gaining access to the panel
chambers. All sealants and
tapes must be
polycarbonate-compatible,
and all silicone must be
neutral and solvent-free.
wall profile
System with
reinforced
aluminium profile
System with 32mm
square pipe

8. DISADVANTAGES
• polycarbonate is not as clear as the glass and in office installations you need to leave
open parts on the facade to be filled with glass.
• A disadvantage of polycarbonate compared to glass is that degradation occurs with time.
Sheet degradation is measured using a yellowness index called ΔYI
• In addition to change in color correlates with a proportionate amount of loss of the
sheet's ability to transmit light.
• A 10 year warranty is the industry standard for polycarbonate sheet products while
the working life is considerably longer.
• Actual performance depends on many aspects like individual applications and local
environmental factors. With the addition of special coating UV layers 20 years of
lifespan is also possible.
• Most thermoplastic materials suffer from slow deterioration as a result of UV
exposure. Build ups of moss and dirt will also lead to lower levels of light transmission
and thus a lowering of performance.
• During installation workers should always be careful to fix the panels with the UV
protected side on the exterior elevation. This is marked on the protective film and
may also be discreetly printed along the side of the sheet.

9. The polycarbonate facade of the Herma Parking Building
The architect designed the folded angles of
polycarbonate at anywhere from 60 to 150 degrees, so
the slightly differing angles of elevation create a
rhythmical flow with the speed of the vehicles on the
road. Meanwhile, the polycarbonate panels on the rear
side, facing the downtown buildings, don’t have any
angles, a strategy intended to harmonize with the
rigidness of the back street.
EXAMPLE
For the facade, the architect chose five-layered polycarbonate, coating the inside white and
the outside purple, with IR and UV coating increasing the light diffraction. As a result,
according to the viewing angle, the facade seems to show through and sometimes has an
opaque purple elevation. Dependent on sunlight or night-time illumination, it displays
totally different colors and elevation effects.

10. PTFE (Teflon)
• PTFE, or polytetrafluoroethylene, is a Teflon®-coated woven fiberglass membrane
that is extremely durable and weather resistant.
• The woven fiberglass gives the PTFE fiberglass membrane its mechanical
strength. These filaments, known as beta glass, are the smallest diameter
available and provide the membrane with maximum flexibility. The fibers are
drawn from hot melt glass through platinum dies into continuous filaments, and
are then twisted and plied into yarn bundles.
• The yarns are woven into a wide structural fabric, which is then coated with PTFE
fiberglass to complete the process.
PTFE fiberglass membranes can be installed in climates ranging from the frigid
arctic to the scorching desert heat with a project life in some cases exceeding 30
years.

11. • PTFE fiberglass coating is chemically inert, capable of withstanding temperatures
from -100°F to +450°F (-73°C to +232°C).
• The low-surface free energy of the material results in an electrical grade fabric
membrane which is readily rinsed by rainwater. It is also completely immune to
UV radiation. This unique combination of inertness, thermal stability and surface
properties make PTFE-coated fabric membrane ideal for projects requiring
superior weather and fire resistance.
New Bangkok International Airport (NBIA)
• PTFE fiberglass membranes reflect as much as 73 percent of the sun’s energy
while holding just seven percent on its exterior surface. Certain grades of PTFE
fiberglass can absorb 14 percent of the sun’s energy while allowing 13 percent of
natural daylight and seven percent of re-radiated energy (solar heat) to transmit
through.

12. • PTFE's fiberglass yarns maintain ultimate tensile strength of 500,000 PSI and a
modulus of elasticity of 10.5 PSI x 106 compared to steel, which offers 40,000
PSI and 29 PSI x 106respectively. Under normal conditions, the fabric behaves
elastically and does not undergo significant stress relaxation or creep.
The screen that encloses the third side of the Burj al Arab atrium is made of 1mm
thick glass fibre fabric with a Teflon coat to stop the dirt sticking. The screen is the
largest of it’s type and covers an area of one and a half football pitch and is hung
from the top of the building by over a kilometre of 52mm cable.

13. EXAMPLE
The façade of the recently expanded King
Fahd National Library .
The bold, yet contextual, design is crucial
to the performance of the building, which
is located in the extreme climate of
Riyadh, Saudi Arabia.
Functionally speaking, the approximately
1,000 twisted squares of textile shade the
building and infuse its interior spaces with
natural light without completely blocking
occupant views.
In the extreme temperatures of Riyadh,
Saudi Arabia, the glass-enclosed
expansion to King Fahd National Library
gets dimensional and heat relief with a
tensile fabric façade.
The design also pays homage to the
region’s culture. The tensile structure
references the local nomadic tradition—as
recently as 1950, 40 percent of the
country’s population lived in tents—while
the intricate pattern echoes the rich history
of geometric Islamic ornamentation.
:Fahd National Library .

14. In a city that often experiences temperatures exceeding 100 F, “a glass building is
nonsense,” Lücking says. But the firm clung to its concept of wrapping the existing
library with a glass edifice by shading the glazing with a polytetrafluoroethylene
(PTFE)-coated, woven-glass-fiber membrane
The awnings block 93 percent of the incoming sunlight all day,
save for about 30 minutes at daybreak and 30 minutes at sunset.
To avoid turning their glass building into a greenhouse, the
designers left a 2-meter gap between the tensile fabric façade and
the building. Convection circulates hot air up and out of the cavity.
That geometry was the starting point, Lücking says. “The rhythm of
the façade dictated everything else ... the grid of structural
elements and the interior space.”
3D-diagram of the tensile-cable structure
that supports the awnings