This is the second post in our Super Natural Materials series – you can view the whole series here.
Zinc is an abundant, lightweight and shiny metal which has long been used in construction for roofs and vertical cladding. It is perhaps most extensively used in Paris, where the majority of roofs have been zinc since Napoleonic times. It’s currently becoming more popular for civic and corporate buildings that need to last a long time, as well as increasingly for homes as its sustainability benefits gain prominence.
This post will outline the benefits of building with zinc, plus several examples of the diverse kinds of buildings that utilise it.
Benefits of building with zinc
- Very durable
Zinc roofs can last over 100 years, because it doesn’t rust, instead it ‘heals’ itself with a protective patina that come back after scratching, formally known as zinc hydroxyl-carbonate. By comparison, clay or concrete tiles can be expected to last 60 years. Because of the protective patina, zinc is not sensitive to rust or UV and is very low maintenance. This counteracts the high initial cost.
Water run-off doesn’t pick up chemicals or toxins to leach into soil and water.
Zinc is a fungistat that prevents build-up of mould or moss but water runoff is not toxic to plants, unlike copper which is fungicidal but also harmful to plants. Illustrating its lack of toxicity, zinc is actually a micro-nutrient, present in the bodies of people and animals and required in small quantities for optimum health.
While not renewable, this finite metal is extremely abundant compared with other resources. In fact it’s the 24th most abundant element in the Earth’s crust. Estimated zinc ore reserves are 34 million tonnes, enough for 700 years at present rates, not taking recycling into account. And it is almost entirely recyclable, so with smart circular economy processes we should be able to make it last indefinitely. Even mining and processing zinc ore is much less energy-intensive than other metals, because it is lightweight and has a low melting point.As VMZINC, a leading zinc supplier, tells ArchDaily:
“A big sustainability advantage for zinc over other metals is that it takes much less energy to refine zinc than aluminum, copper, or stainless steel. For instance, the energy required to produce zinc from ore is a quarter of that needed to make aluminum and half of that needed for copper and steel.”
- Very flexible
Zinc can be cut, curved and folded to produce interesting and diverse shapes – one of the properties that has made it so popular with architects. It’s very malleable, lightweight and soft, yet also strong. Suitable for all roof pitches between 5% – 90%.
- Attractive aesthetics
Undoubtedly a key reason for zinc’s popularity is it’s natural beauty. The material is a smooth and shiny silvery colour. As it weathers, it develops an attractive dappled patina (which also protects it, see above). You can also buy it pre-weathered or coloured, allowing even more creative designs with two or more shades.
Examples of building with zinc
Projects using zinc designed by Koru Architects
For the reasons above, we often utilise zinc for roofing of our projects. Here’s three examples.
This award-winning zero-carbon detached house and studio is our director’s home and also houses the Koru Architects company office.
It is the a winner of the RIBA Downland Prize 2011 and the Green Apple Award for Architecture 2016. Natural materials, low in embodied energy, have been used throughout: including hemp insulation, oak cladding, zinc roofing and lime render. The living room roof also features a green sedum roof.
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This detached rural home built to passivhaus standards sits on an agricultural smallholding in the Sussex countryside. The house is constructed from natural materials low in embodied energy including local Sussex sandstone, Sweet Chestnut timber cladding, zinc roofing and sheep’s wool insulation.
This 4-bedroom property is a contemporary low-energy reimagining of an Arts and Crafts style house. The design uses a palette of natural and traditional materials such as brickwork, clay tiles, zinc and a timber frame.
Other zinc architecture projects
Given the flexibility of zinc, it can be utilised for a very diverse range of buildings. Here are just a few more examples…
— AandD (@archanddesign) January 12, 2017
An example of a contemporary building with ribbed zinc cladding coming down from the roof to the ground, covering the whole exterior.
— Hl Metals Ltd (@hl_ltd) January 24, 2017
This is a classic grey zinc roof with zinc cladding coming part way down the wall of the larger wing of the house.
What a roof!
Spain’s Casa del Acantilado’s zinc shingles adapt to every curve of the building’s roof form. pic.twitter.com/n9lMGv80gy
— WestPacRoofing (@WestPacRoofing) February 5, 2017
Finally, here’s a very unusual curvy roof made with zinc, showing its extraordinary flexibility.
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