Curtain Walls

Paras Gulia Neeraj Kalra4th year

Introduced by – Ar. Ashok Puri

Contents

• Introduction to Curtain Walls• Origin• Types• Concerns In system• Infills• Similar systems

Introduction to Curtain Wall• A curtain wall system is an outer covering of a building in which the

outer walls are non-structural, but merely keep the weather out and the occupants in.

• As the curtain wall is non-structural it can be made of a lightweight material reducing construction costs. When glass is used as the curtain wall, a great advantage is that natural light can penetrate deeper within the building.

• The curtain wall façade does not carry any dead load weight from the building other than its own dead load weight.

• Curtain wall systems are typically designed with extruded aluminum members, although the first curtain walls were made of steel. The aluminium frame is typically infilled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting.

Origin of Curtain Wall

• Buildings were constructed with the exterior walls of the building (bearing walls, typically masonry) supporting the load of the entire structure.

• 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

Glass curtain wall of the Kant-Garage (parking garage), Berlin,

1929/30

Glass curtain wall of the Bauhaus Dessau, Germany 1926

• Oriel Chambers (1864) and 16 Cook Street (1866), both built in Liverpool, England, by local architect and civil engineer Peter Ellis, are characterised by their extensive use of glass in their facades.

• Towards the courtyards they even boasted metal framed glass curtain walls which makes them two of the world's first buildings to include this feature.

• The extensive glass walls allowed light to penetrate further into the building utilizing more floor space and reducing lighting costs in short winter months.

• The 1970s began the widespread use of aluminum extrusions for mullions. Aluminum offers the unique advantage of being able to be easily extruded into nearly any shape required for design and aesthetic purposes. Today, the design complexity and shapes available are nearly limitless. Custom shapes can be designed and manufactured with relative ease.

Oriel Chambers, Liverpool, England,1864

16 Cook Street, Liverpool, England,1866.

Extensive use of curtain walls in present times at large scaleImage- Cybercity ,Gurgaon

Curtainwall Types

• Storefront • Stick Wall• I-Beam Wall• Pressure Wall• Unitized Wall• Window Wall

Storefront• “Storefronts” are non-load-bearing glazed

systems that occur on the groundfloor, which typically include commercial aluminum entrances.

• They are installed between floor slabs, or between a floorslab and building structure above. Typically field-fabricated and glazed, storefronts employ exterior glazing stopsat one side only.

• Provision for anchorage is made at perimeter conditions. While sometimes used as a low-cost alternative to curtain wall systems for lowrise buildings, performance requirements for storefront are generally less stringent,and materials may require more frequen tmaintenance.

Stick Wall• “Stick” curtainwall systems are shipped in

pieces for field-fabrication and/or assembly. • These systems can be furnished by the

manufacturer as “stock lengths” to be cut, machined, assembled, and sealed in the field, or “knocked down” parts pre-machined in the factory, for field-assembly and -sealing only.

• All stick curtainwalls are field-glazed. 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.

• Shipped in pieces as: Stock Lengths-or-Knocked Down (KD)

I-Beam Walls• Once very popular, “I-Beam” walls have

seen market penetration decrease. “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 labor. Of course, maintaining vapor retardant continuity at interior trim joints can be challenging if any positive building pressure is present

Pressure Walls• any stick curtainwalls are called “pressure

walls,” because exterior extruded aluminum plates are screwapplied to compress glass between interior and exterior bedding gaskets.

• A snap-on cover or “beauty cap” is then used to conceal pressure plate fasteners. 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.

• Many critical seals are necessary, even in systems that are designed to drain or “weep” rain penetration from the system back to the exterior. “Compartmentalization” of each lite is strongly recommended to isolate glazing pockets.

Pressureplate andsnap-oncover

Unitized Walls

• Factory-assembled and factory– glazed under controlled conditions.

• Units are hung from the floor above on pre-set anchors.

• To accomplish as many critical seals as possible in controlled factory conditions, and minimize dependence on field labor, “unitized” curtainwall systems have been developed.

• Unitized curtainwalls are factoryassembled and -glazed, then shipped to the job site in units that are typically one lite wide by one floor tall. Most unitized curtainwall systems are installed in a sequential manner around each floor level, moving from the bottom to the top of the building.

• Only one unit-to-unit splice, usually a translucent silicone sheet or patch, needs to be field-sealed. Seal bedding is visible through the sheet. Only one anchor per mullion needs to be attached to the face of the floor slab. The horizontal gutter weather-seal is sometimes called a “chicken head” detail, due to its unique configuration. Interlocking unitized curtainwall frame members are weather-stripped to seal to one another, both horizontally and vertically. This accommodates thermal expansion and contraction, inter-story differential movement, concrete creep, column foreshortening, and/or seismic movement.

Window Wall• Window wall” systems span from the top

of one floor slab to the underside of the slab above.Window wall employs large, sidestacking 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 aluminum 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.

Concerns

• Loads-Dead load, Wind load, Seismic load, Snow load, Thermal load, Blast load

• Air Infiltration• Water penetration• Deflection• Strength• Thermal criteria

Infills

• Glass• Fabric veneer- Unlike glass or stone, fabric is much faster to install,

less expensive

• Stone veneer- Thin blocks (3 to 4 inches (75–100 mm)) of stone

• Panels- Metal panels, fiber-reinforced plastic (FRP), stainless steel etc .

• Louvers• Windows and vents

CURTAINWALL AND COMPONENTS

• Profiles and depths will vary, but component names are fairly similar

• Some of the terminology……..

Head: The horizontal frame member which forms the top of a frame

Head

Sill: The bottom horizontal in the framing system

Sill

Jamb: The vertical frame member forming the side of an opening, or the side of a door

Jamb

Mullion: A vertical framing member separating fixed lights of glass

Mullion

Intermediate Horizontal: The horizontal member used between two lites of glass

IntermediateHorizontal

Pressure Plate: An exterior extrusion that is mechanically fastened to hold the glass in place in CURTAINWALL applications

PressurePlate

Cover: The finished snap on piece at the exterior of the building applied to the pressure plate

Cover Cover

Pressure Bar

Screw Splines: Anchoring method in which screws are used in splines to assemble the framing

Screw Splines

Shear Blocks: Anchoring system utilizing an aluminum block to secure horizontals to the verticals

ShearBlocks

Steel Reinforcement: Steel channel or tube needed to stabilize the mullion in certain conditions- can be used with curtainwall OR storefront

SteelReinforcement

Other Systems

SPİDER CURTAİN WALL SYSTEM CAPPED CURTAİN WALL SYSTEM

HALF CAPPED CURTAİN WALL SYSTEM

SİLİCONE STRUCTURAL GLAZİNG SYSTEM