Aluminum

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Summary

Aluminum is a low-density, non-ferrous metal used in buildings as alloyed extrusions, sheet, and plate in tempers such as 6063-T5 and 6063-T6. 🟠Specify alloy, temper, and finish together: they set strength, thermal movement, and durability of frames, cladding, and roofing.

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[!abstract] Contents

Terminology

ADM: Aluminum Design Manual, the Aluminum Association design specification
Alloy / temper: four-digit alloy number plus a temper suffix (6063-T5, 6063-T6) that sets strength
Mill finish: as-extruded or as-rolled surface, no coating
Anodizing: electrochemical oxide coating grown from the metal surface
Billet: cast aluminum log heated and pushed through a die to make an extrusion
PVDF: polyvinylidene fluoride paint, specified to AAMA 2605
MCM: metal composite material, thin aluminum skins bonded to a core, used as wall panels

History and demand

Discovery and early use

1824: Hans Christian Ørsted produced the first aluminium (presented 1825); Friedrich Wöhler made powder in 1827 and small pieces in 1845
1856: Henri Sainte-Claire Deville set up the first industrial production by reducing aluminium chloride with sodium
1885: the Washington Monument received an aluminium cap, used as a lightning rod

Use in construction

1886: Charles Martin Hall and Paul Héroult independently developed the electrolytic process still used today; Bayer's alumina process followed in 1889
1890s to early 1900s: falling prices opened consumer uses; real price fell from $14,000 per ton in 1900 to $2,340 in 1948 (1998 dollars)
Mid-20th century: use expanded into basic construction and interior finishing

Demand trend

Rising: output grew from 6,800 metric tons in 1900 to over 50 million tons in 2013; global primary production reached 73.8 million tonnes in 2025, up 1.06 percent from 2024 (AL Circle citing IAI data)

Composition and production

Product forms

Extrusions: framing, mullions, and thermally broken frames; billet is 47% primary and 53% recycled metal on average in North American industry-average extrusion data
Sheet and plate: roofing, wall panels, and flashing (ASTM B209)
Siding and MCM panels: thin-gauge cladding

Grades and types

6063-T5: extrusion, ADM non-welded values for thickness up to 0.5 in.: Fu 22 ksi, Fy 16 ksi
6063-T6: extrusion, same thickness: Fu 30 ksi, Fy 25 ksi
Welded 6063-T5: Fu 17 ksi, Fy 8 ksi; welds cut strength sharply

Properties

Physical

Density: 2.699 g/cm³ at 68°F, about 169 lb/ft³

Mechanical

Modulus of elasticity: 10,100 ksi (6063)
Strength: see Grades and types (ADM values for 6063 extrusions)

Thermal and moisture

Thermal conductivity: about 1,640 Btu·in./(h·ft²·°F) (237 W/(m·K))
Coefficient of thermal expansion: 12.7 × 10⁻⁶ in./in./°F (22.87 × 10⁻⁶/K at 68°F)

Fire behavior

Melting point: 1,221°F (660°C)

Durability

Corrosion: thin oxide film forms on exposed surfaces; anodized and PVDF-coated finishes extend exterior life
Anodic coating salt spray: AAMA 611 Class I 3,000 hours, Class II 1,000 hours

Standards

Material specifications

AA ADM: Aluminum Design Manual
AA ASM 35: Aluminum Sheet Metal Work in Building Construction
ASTM B209: aluminum and aluminum-alloy sheet and plate
ASTM B221: aluminum and aluminum-alloy extruded bars, rods, wire, profiles, and tubes (extrusion rows in ADM tables)
AAMA 611: anodic coatings for architectural aluminum
AAMA 612: anodic coating with clear organic coating
AAMA 2605: high-performance organic coatings (PVDF)

Uses in buildings

Building elements

Aluminum Windows, Fixed Windows, Awning Windows, Double-Hung Windows, Horizontal Sliding Windows: thermally broken extruded frames in commercial and window-wall work
Casement Windows, Wood and Clad Wood Windows: extruded aluminum cladding over wood interiors
Aluminum Storefront Doors, Curtain Wall Systems, Automatic and Revolving Doors: extruded stiles, rails, mullions, and framing
Sliding and Folding Glass Wall Systems, Skylights and Roof Windows, Overhead Sectional Doors: panel frames, skylight frames, and full-view glazed sections
Standing Seam Metal Roofing, Roof Drainage Systems: roof panels, gutters, and leaders
Rooftop Solar PV: module frames
Linear LED Fixtures, Recessed Troffers, Track and Rail Lighting, Cove and Indirect Lighting, Site and Pole Lighting: extruded housings, tracks, channels, and poles
Panelboards, Switchboards, Transformers: bus bars and windings as an alternative to copper
Conduit and Raceways, Ductwork and Air Distribution: aluminum conduit, and ducts for corrosive or kitchen exhaust
Metal Wall Panels: siding and metal composite material wall panels

Pros and cons

Pros

Density about one-third of steel (2.699 g/cm³ against 7.75 to 8.05 g/cm³)
Extrudes into complex framing profiles
Anodizing and PVDF finishes available in many colors
Billet averages 53% recycled content in industry-average extrusion data

Cons

High thermal expansion (12.7 × 10⁻⁶ in./in./°F) drives frame and joint movement
Low melting point of 1,221°F
Welding reduces strength sharply (6063-T5 Fy 16 ksi falls to 8 ksi)
Mill-finish extrusion carries 7.87 kg CO2e per kg, before finishing

Design considerations

Movement

Expansion about 0.15 in. per 10 ft for a 100°F temperature swing (calculated from 12.7 × 10⁻⁶ in./in./°F)
Allow for movement in frames, panels, and sealant joints

Joining and fastening

Welded zones carry reduced design strength (see Grades and types)

Finishes and treatments

Mill finish: interior or concealed use
Anodizing, AAMA 611 Class I: at least 0.7 mil; the usual exterior specification
Anodizing, AAMA 611 Class II: 0.4 to 0.7 mil; interior or light exterior use with regular cleaning
PVDF paint, AAMA 2605: highest color and gloss retention, chalk resistance, and resistance to acids and alkalis
Anodic plus clear organic, AAMA 612: very thin anodic layer sealed with clear organic coat

Sustainability

Embodied carbon

Mill-finish extrusion, North America: 7.87 kg CO2e per kg of aluminum (about 3.6 kg CO2e per lb), Aluminum Extruders Council industry-average EPD, 2022; 77% from billet
Anodizing adds about 6%; liquid or powder paint adds about 17%
EPD covers about 38% of 2020 North American extrusion; in effect through August 2027

Recycled content and end of life

Billet assumption: 47% primary, 53% recycled aluminum

Manufacturing and cost

Main manufacturers and suppliers

Trade association: The Aluminum Association; extruders: Aluminum Extruders Council.

Sources

Wikipedia: Aluminium, https://en.wikipedia.org/wiki/Aluminium
AL Circle: world primary aluminium production 2025, https://www.alcircle.com/news/world-primary-aluminium-production-growth-hits-5-year-low-in-2025-as-gcc-output-weakens-and-china-nears-45mt-ceiling-117046
Beamdimensions (ADM tables for 6063): https://beamdimensions.com/materials/Aluminium/ADM_(Non-Welded)/6063
UpCodes: 2024 IBC Chapter 20 aluminum, https://up.codes/viewer/department-of-defense/ibc-2024/chapter/20/aluminum
UpCodes: 2024 IBC Chapter 15 roof assemblies (Table 1507.4.3), Chapter 15 Roof Assemblies and Rooftop Structures: Department of Defense Building Code 2024 | UpCodes
UpCodes: 2024 IBC Chapter 14 exterior walls, https://up.codes/viewer/department-of-defense/ibc-2024/chapter/14/exterior-walls
Light Metal Age: AEC carbon accounting, https://www.lightmetalage.com/news/industry-news/extrusion/preparing-extruders-for-carbon-accounting-aecs-new-measurement-tool/
Aluminum Extruders Council: updated extrusion EPDs, https://aec.org/aec-releases-updated-aluminum-extrusion-epds
Window and Door: anodize finishes, https://www.windowanddoor.com/blog/check-spec-ensure-anodize-finishes-deliver-durability
Alumicor: anodized finishes, https://alumicor.com/2024/02/anodized-advantage-understanding-the-benefits-and-options/