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)