Chapter 21
Cladding with Metal & Glass
Metal & Glass Curtain Walls
Connected to , but isolated from, the building frame
Support only their weight & resist lateral forces
Insulated & thermally broken
Maximize comfort, minimize H/C costs & condensation
Incorporate advanced glazing & spandrel materials
(luminous & thermal properties)
Gaskets & drainage to prevent water infiltration
Architectural appearance & ease of installation
Internal features, fasteners, etc. … concealed
Multiple extrusion shapes, finishes, & colors
Metal Frames - Extrusions
Aluminum - the metal of choice
Doesn’t corrode (beyond a thin oxidized layer)
Can accept, and hold, a variety of finishes
Economically fabricated - extruded (multiple shapes)
Extrusion
Heated metal is forced through a die
Continuous ribbon of material
Highly precise cross-section
Multiple shapes available
Die
Extrusion
Thermal Breaks
Aluminum - not a good insulator
Cold climates - inside metal cold
 Interior condensation (even frost)
Hot climates - metal cooled by AC
 Exterior condensation
System Needs - Thermal Break
Thermal Break
Definition
“internal components of insulating
material that isolate the aluminum on
the interior side of the component
(mullion) from aluminum on the
exterior face”
Construction (rubber or plastics)
Thermal
Break
Thermal Breaks
Aluminum Finishes
Natural oxidized finish - not attractive
Applied Coatings
Annodized coatings
Organic coatings
 Multi-coat sprayed
Powder Coatings
 sprayed powder - baked
Polyvinyl chloride (PVC)
Mechanical Finishes
 brush, sandblast, polish, etc.
Annodized Coatings
Oxidized coating produced in an acid bath
Additives can produce a number of colors
Most common - bronzes
Advantages:
Extremely hard coating
Very good resistance to weather & fading
Disadvantage: color consistency
Sampling
of
Mullion Colors
Aluminum & Glass L.C.
Assembly
Components
Mullions
Shear Blocks
Screws
Gaskets
“Snap-ons”
Modes of Curtain Wall Assembly
Stick Systems
Unit System
Panel Systems
Column Cover & Spandrel System
Stick Systems
Components
•Vertical Mullions
• Horizontal Mullions
•Glass Panels
•Spandrel Panels
Assembly
•In the “Field”
Advantages
•Minimal shipping bulk
•Latitude for field adj.
•“Hand” set components
•Economical
Disadvantages
•Built on “site”•Quality Control
‘Stick’ Systems
Unit Systems
Components
•Pre-assembled
Framed Unit
Assembly
•Factory Assembly
•Field unit installation
Advantages
•Minimizes on-site labor
•Factory - “controlled”
Disadvantages
•Larger shipping bulk
•Site protection of mat’l
•Heavier wgt. - cranes?
Panel Systems
Components
•Homogenous units
•Formed from sheet metal
Assembly
•Fabrication - shop
•Field installed
Advantages
•Minimizes on-site labor
•Factory - “controlled”
Disadvantages
•$ of custom molds
•Larger shipping bulk
•Site protection of mat’l
•Heavier wgt. - cranes?
Column Cover & Spandrel
“emphasizes the structural module of the building”
Components
•Column Covers
•Spandrel panels
•Glazing units
Assembly
•Field installation
Disadvantages
•Field Assembly
•$ for custom design
(no “standard” blg. module)
Column Cover & Spandrel
Types of Glazing
Outside Glazed
“Glass installed (or replaced) from the outside”
Simple mullion system
Typically more economical on low-rise blgs.
Inside Glazed
“Glass installed (or replaced) from the inside”
More elaborate mullion components/system
 Higher material costs
Typically more convenient & economical on tall buildings
 Lower field labor costs
Snap Cover
Outside glazed “stick” system
Shear Block
Thermal Break
Pressure Plate
Stick system
“externally” glazed
Thermal Break
Interior Gaskets
Pressure Plate
One Piece Extrusion
Two Piece Extrusion
Building Anchorage
Mullion “Splicing”
Inside Glazed
Inside Glazed
continued
Bottom Half of the
Horizontal Mullion
Installed after
Glass Installation
Expansion Joints
Metal and Glass
Aluminum
High coefficient of thermal expansion
Twice the coefficient of Glass
Aluminum to Glass expansion / contraction
Gaskets
Blocks (spacers) keep glass form Walking w/i opening
Aluminum mullion Expansion / Contraction
Telescoping joints in vertical mullions
Horizontal mullions cut slightly short
Sloped Glazing - Skylight
Sloped Glazing - Skylight
Unique Problems w/
Sloped Glazing
•Gravity “pulling” H2O thru
the “System”
•Internal Condensation
•Both can cause
•discomfort - occupants
•damage
Solution
• “Internal Drainage System
Sloped Glazing - Skylight
Cladding In Metal
Sheets of Copper
Stainless Steel
SS Jointing
Painted Metal Panels
Metal Panels
Aluminum Panels
Aluminum Panel Column Covers
Aluminum Panel Column Covers
Aluminum Panels
Experience Music Project
‘Rock n Roll Museum’
Seattle
(6 photos)
Stainless Steel,
Copper,
and Coated
Metal Panels
Curtain Wall Design
Complex & Specialized Process (often a proprietary
system adopted that meets design criteria)
Design ‘specialists’ consulted
Concept drawings prepared by A&E
Detailed design documents prepared by manufacturer
– followed by shop dwgs.
A/E reviews to ensure design compliance
Full-scale testing
Manufacturer and then erection
Sustainability in Aluminum Cladding
Raw material plentiful, but refining requires
considerable energy (embodied energy 6x steel)
Large quantities of water required for smelting &
waste water contains pollutants
Aluminum recycled at a very high rate
Extrusions easy to produce and light weight
Powder coating release no solvents into the
atmosphere
Low maintenance, but highly conductive (thermal
breaks required)