Zinc
Zinc is a bluish-white metal valued in architecture for its distinctive appearance, natural patina development, excellent corrosion resistance, and self-healing properties that contribute to exceptional longevity in building applications.
Composition
Architectural zinc is typically supplied as zinc alloy with small amounts of copper and titanium (commonly referred to as 'titanium zinc' or 'architectural zinc') to improve workability and mechanical properties. The standard alloy contains approximately 99.995% zinc with 0.08-0.2% copper and 0.07-0.12% titanium, conforming to EN 988 standards for rolled zinc products in construction.
Properties
Density
445 lbs/ft³ (7,140 kg/m³)
Lighter than steel and copper, but heavier than aluminum, offering a good balance of weight and structural integrity.
Tensile Strength
14,500-21,750 psi (100-150 MPa)
Lower strength than many structural metals, but sufficient for self-supporting cladding and roofing applications.
Melting Point
787°F (419°C)
Relatively low melting point compared to other architectural metals, requiring consideration in fire-rated assemblies.
Thermal Expansion
16.5 × 10⁻⁶ in/in/°F (30 × 10⁻⁶ m/m/°C)
Higher than many metals, requiring careful detailing to accommodate movement.
Corrosion Resistance
Excellent
Forms a protective patina of zinc carbonate that prevents further corrosion and has self-healing properties for small scratches and damage.
Patina Development
Natural gray patina
Initially bright and reflective, develops a matte gray patina over 6-24 months depending on environmental conditions, eventually stabilizing to protect the underlying metal.
Applications
Roofing Systems
Used for standing seam roofing, shingles, and panels, offering excellent weather protection with a lifespan of 80-100 years. Zinc roofing is lightweight, requiring less structural support than clay or concrete tiles, and performs well in various climates from coastal to urban environments.
Wall Cladding
Applied as facade panels, shingles, or cassettes in various profiles and installation systems. Zinc cladding provides a distinctive aesthetic that evolves over time, with options for pre-weathered finishes to achieve immediate visual consistency.
Rainwater Systems
Manufactured into gutters, downspouts, and flashing components that resist corrosion and complement zinc or other roofing materials. Zinc rainwater goods develop matching patina with the roofing system and typically last the lifetime of the building.
Interior Applications
Used for wall panels, column covers, and decorative elements in contemporary interiors where a distinctive metallic aesthetic is desired. Interior zinc typically maintains its original appearance longer due to less exposure to weathering elements.
Ornamental Elements
Crafted into decorative features such as spires, dormers, cupolas, and custom architectural details, taking advantage of zinc's malleability and formability for complex shapes and designs.
Solar Protection
Incorporated into sunshades, screens, and louvers that provide both functional solar control and aesthetic integration with zinc-clad building envelopes.
Advantages
- Exceptional longevity with typical lifespan of 80-100 years for roofing applications
- Self-healing protective patina that repairs minor scratches and damage
- Low maintenance requirements with no need for painting or coating
- Distinctive appearance that evolves naturally over time
- Lightweight compared to many roofing materials, reducing structural requirements
- Excellent malleability allowing for complex forms and details
- Fully recyclable with high collection rates at end of life
- Compatible with rainwater harvesting systems
Limitations
- Higher initial cost compared to many conventional roofing and cladding materials
- Requires skilled installation and proper detailing for best performance
- High thermal expansion requiring careful accommodation in design
- Relatively soft and susceptible to mechanical damage
- Not suitable for direct contact with certain materials (copper, uncoated steel, concrete)
- Patina development may be uneven initially, particularly in partially sheltered areas
- Potential for oil-canning (waviness) in flat panel applications
- Can be noisy during heavy rainfall when used for roofing
Sustainability Profile
Zinc offers excellent sustainability credentials due to its longevity, recyclability, and relatively low environmental impact in production. With a lifespan of 80-100 years for roofing and cladding applications, zinc's embodied energy is amortized over an exceptionally long service life. The material is 100% recyclable without loss of properties, and approximately 95% of architectural zinc is collected and recycled at end of life in developed countries. Current production includes 30-40% recycled content on average. Zinc production requires approximately 30-40% less energy than copper and 20% less than aluminum. The material requires no maintenance coatings, eliminating VOCs and other chemical treatments throughout its lifespan. Zinc is an essential micronutrient, and the runoff from zinc surfaces is generally not environmentally problematic in most contexts. Mining impacts remain a consideration, though modern zinc mining has significantly improved environmental practices. Zinc's low melting point (419°C) means less energy is required for recycling compared to many other metals.