chapter 21 cladding with metal & glass. metal & glass curtain walls connected to, but...
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Chapter 21Cladding with Metal & Glass
Metal & Glass Curtain Walls
Connected to , but isolated from, the building frameSupport only their weight & resist lateral forces
Insulated & thermally brokenMaximize comfort, minimize H/C costs & condensation
Incorporate advanced glazing & spandrel materials (luminous & thermal properties)
Gaskets & drainage to prevent water infiltration
Architectural appearance & ease of installationInternal features, fasteners, etc. … concealedMultiple extrusion shapes, finishes, & colors
Metal Frames - Extrusions
Aluminum - the metal of choiceDoesn’t corrode (beyond a thin oxidized layer)
Can accept, and hold, a variety of finishesEconomically fabricated - extruded (multiple shapes)
Extrusion
Heated metal is forced through a dieContinuous 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)
ThermalBreak
Thermal Breaks
Aluminum Finishes
Natural oxidized finish - not attractiveApplied CoatingsAnnodized 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 colorsMost common - bronzes
Advantages:Extremely hard coatingVery good resistance to weather & fading
Disadvantage: color consistency
Sampling
of
Mullion ColorsAluminum & Glass L.C.
AssemblyComponents
MullionsShear Blocks
ScrewsGaskets
“Snap-ons”
Modes of Curtain Wall Assembly
Stick Systems
Unit System
Panel Systems
Column Cover & Spandrel
System
Stick SystemsComponents
•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 SystemsComponents
•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 SystemsComponents
•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 GlazingOutside Glazed
“Glass installed (or replaced) from the outside”Simple mullion systemTypically 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
Outside glazed “stick” system
Pressure Plate
Thermal Break
Snap Cover
Shear Block
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 afterGlass Installation
Expansion JointsMetal and Glass
Aluminum High coefficient of thermal expansionTwice the coefficient of Glass
Aluminum to Glass expansion / contraction GasketsBlocks (spacers) keep glass form Walking w/i opening
Aluminum mullion Expansion / ContractionTelescoping joints in vertical mullionsHorizontal 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 pollutantsAluminum recycled at a very high rateExtrusions easy to produce and light weightPowder coating release no solvents into the atmosphere Low maintenance, but highly conductive (thermal breaks required)