Curtain walls are non-load bearing exterior walls that hang from the building structure. They allow for larger windows and more open floor plans compared to load bearing walls. Common materials for curtain walls are glass and aluminum due to their strength, light weight, and ability to limit heat transfer. Curtain walls are classified based on their method of construction, with common types being stick wall, unitized wall, and window wall systems. Proper design of curtain wall systems is important to handle loads, transfers stresses to the building structure, and prevents air and water infiltration.

1. ADVANCE CONSTRUCTION & MATERIALS
A SHORT NOTE ON
CURTAINWALLS

2. What is Curtain wall?
A wall which encloses the space within a building but
does not support the roof.
Non-load-bearing exterior wall that hangs (like a curtain)
from the face of floor slabs, regardless of construction or
cladding material
Glass curtain wall of the
BauhausDessau, 1926
Ford Metro.Inc
Rochester, 1985

3. One of the oldest curtain-wall
in the world, Bucharest
Developers previously used steel to frame curtain walls.
But this was problematic, as steels acts as a conductor
and creates thermal bridges that contribute to heat loss
in a system.
Today, glass and aluminum curtain wall combinations are
more popular for use as cladding and for exterior walls.
The benefits of this combination include limited air
leakage, prevention of rain penetration and limited
excessive heat loss (or gain).
The development and widespread use of structural
steel and later reinforced concrete allowed relatively
small columns to support large loads and the exterior
walls of buildings were no longer required for structural
support.
The exterior walls could be non-load bearing and thus
much lighter and more open than the masonry load
bearing walls of the past.
This gave way to increased use of glass as an exterior
façade, and the modern day curtain wall was born.

4. Classification:
Curtain walls can be classified by their method of
fabrication and installation into the following
general categories.
• Storefront
• Stick Wall
• I-Beam Wall
• Pressure Wall
• Unitized Wall
• Window Wall

5. Glazed systems that occur on the ground floor,
and typically include aluminium entrances.
Installed between floor slabs, or between a floor
slab and building structure above
Storefront
“Storefronts” are non-load-bearing
glazed systems that occur on the ground
floor, which typically include commercial
aluminium entrances. They are installed
between floor slabs, or between a floor
slab and building structure above.
storefronts employ exterior glazing stops
at one side only
sometimes used as a low-cost
alternative to for low-rise buildings,
performance requirements for storefront
are generally less stringent, and materials
may require more frequent maintenance.

6. Stick Wall
Stick systems are installed on site, component by
component, after being prepared and machined in the
factory and supplied in knock down form.
They get their name from the fact that the vertical
structural mullions (sticks) are fixed first.
After the mullions are secure, the horizontal transoms
are added and then the glazing panels, spandrels and
vents installed in the completed grid; normally using a
pressure plate and face cap.
All stick curtainwalls are field-glazed
stick systems are economical and, if correctly designed,
detailed and installed, extremely reliable. They are,
however, slow to assemble, which may not suit certain
fast track projects.

7. Frame assembly requires the use of
either, a) “shear blocks” to connect
vertical and horizontal framing elements,
or b) “screw-spline” construction, in
which assembly fasteners feed through
holes in interlocking vertical stacking
mullions into extruded races in
horizontals.
Shear block

8. I-Beam Wall
I” or “H” shaped, structural, vertical back
members are set into openings in the
field, with horizontals then clipped to
verticals.
After glazing, extruded aluminum
interior trim is cut and snapped into
place at vision areas. Since unexposed
spandrel areas receive no interior trim,
savings in material and finish (painting
or anodizing) can result, partially offset
by added field labour
maintaining vapor retardant
continuity at interior trim joints can be
challenging if any positive building
pressure is present.
Interior trim at vision areas. No finish
required at spandrel areas

9. Pressure Wall
Many stick curtainwalls are called
“pressure walls,” because exterior
extruded aluminium plates are screw applied
to compress glass between
interior and exterior bedding gaskets. A
Snap-On cover or “beauty cap” is then
used to conceal pressure plate fasteners
“Compartmentalization” of each lite is
strongly recommended to isolate
glazing pockets
Performance of any field-assembled or
field-glazed curtainwall is only as good
as field workmanship allows, limited by
variables such as weather, access, and
job site dirt and dust. Pressure plates and snap-on covers
at exterior, with joints allowing
thermal expansion.
Pressure
plate and
Snap-On
cover

10. Unitized Wall
Unitised curtain walling systems are installed as a series
of factory-assembled frames, usually with interlocking
mullions and transoms.
The glazing panels and spandrels are usually factory-
glazed and seals are also applied or prepared in the
factory.
Unitised systems are used where the movement or
deflections in a building are such that a stick system is
inappropriate
Most unitized curtainwall systems are
installed in a sequential manner around
each floor level, moving from the
bottom to the top of the building.
Their principal benefits are speed of installation, minimal
on site labour, and lower installation costs.
However, these are obviated to an extent by the
increased storage and shipping cost, the need for very
careful site handling, and the requirement for expensive
lifting equipment on site.

11. Unitised systems are popular because they eliminate, or
reduce, the need for on site sealing, therefore making
them less reliant on the standard of site workmanship.
However, for unitised systems to perform to their full
potential, it is critical that the brackets to which the
components are fixed are accurately installed.
Unitised systems do not require decanting during
refurbishment contracts.
In conclusion, unitised systems offer the benefits of
factory fabrication in controlled environment, and very
rapid assembly on site.
However, they are generally more expensive than stick
systems and require longer lead times.

13. Window Wall
“Window wall” systems span from the
top of one floor slab to the underside of
the slab above.
Window wall employs large, side stacking
window units, contained in
head and sill receptors, also called
“starters,” which accommodate
movement and drainage, but require
field-applied perimeter sealants.
Slab covers can be fabricated from
aluminium extrusions, sheet, panels, or
even glass.
Window walls easily accept operable
windows, and unlike curtainwall, can
easily be installed non-sequentially.
Hybrid” systems combine
characteristics of multiple wall types.
For example, some four-side silicone
wall systems use stick wall grid frames,
with factory glazed carrier frames
Window
Wall
Head
starter &
two lines
of
perimeter
sealant

14. Aluminium and sheet steel are durable colourfast
cladding solutions. Skyline promotes the Rain screen
Principle on all applicable projects and offers a variety of
metal wall cladding systems. 20-year factory paint
warranties back Skyline installs.
In addition to sheet steel and aluminium, Skyline
incorporates Aluminium Composite Material (ACM) into
our proprietary panel systems. ACM is produced by
bonding two thin sheets of aluminium on either side of
an extruded thermoplastic core under tension. Surfaces
are pre-finished and coil-coated in a variety of paint
finished before bonding. ACM offers the following:
• Rigidity of heavy-gauge sheet metal in a lightweight
aluminium-faced composite material
• Superior flatness, vibration dampening, durability
and ease of maintenance
• An alternative solution to sheet metal or heavy
gauge plate for wall panels systems
• Fabrication in a variety of types of panel systems
Metal Wall Cladding

15. Basic Principles:
Curtain wall systems must be designed to handle
all loads imposed on it as well as keep air and
water from penetrating the building envelope.
The loads imposed on the curtain wall are
transferred to the building structure through the
anchors which attach the mullions to the building.
The building structure design must account for
Dead load
Wind load
Seismic loads
Snow load
Thermal load
Infiltration
Deflection
Smaller wall footprint = resulting in extra floor
area available for occupants
• Parallel scheduling = resulting in faster
erection
• Lighter structure = resulting in material and
transportation savings
• Structural flexibility= resulting in easier
seismic engineering
• Improved light access = resulting in a more
flexible and economical architectural layout
• Structural independency= resulting in a more
flexible architectural layout

16. Dynamic water testing of a curtain wall in a laboratory.
Only 5% of walls generally pass their first test.
Horizontal movement of building structure. Frame is
generally more flexible than walls
Vertical movement of building structure. Note the difference between a rigid
load bearing wall (upper left picture) and the flexible frame support
Various
modes of
deflections

17. Advantages :
• Thermal performance (conduction, solar
radiation, thermal break, comfort)
• Moisture protection (water penetration,
condensation resistance)
• Visual (daylight, aesthetics)
• Sound (acoustics)
• Shadow boxes
• No falling ice and snow
• Maintenance access
• Health & indoor air quality
• Durability & service life expectancy
• Sustainability