Frequently Asked Questions
Please do not hesitate to contact us should you not be able to find an answer to your question below.
Why zinc as opposed to any other roof?
There are many reasons including durability, recyclability and low maintenance but I would say the big reason is visual appearance. It is an attractive material whether it is used on a roof or a façade. The fact that it is not painted means that zinc, especially pre-patinated zinc, offers a warm, vibrant aesthetic that painted surfaces just cannot match.
What about durability? How long will a zinc roof typically last?
When correctly designed and installed a zinc roof can last in excess of 100 years. The BRE Environmental Product Declaration states 100 years. Typically zinc sheets corrode at approx. 2 microns per year and the thinnest zinc sheets sold for roofing in the Australia are 700 microns thick. In a few very severe industrial and marine environments this corrosion rate can increase to 5 or 6 microns. Therefore, occasionally the expected `life span` could drop to 60 years. Liverpool Central Library was fitted with a zinc roof in 1879. At this time the area was extremely polluted and obviously coastal and yet the zinc was only replaced in 2012!
How do you maintain a zinc roof?
The best way of maintaining a zinc roof is simply to let the rain, rain over it and that is it. It is obviously good practice to clear out gutters at the end of the autumn and the occasional visual inspection would not go amiss but no other regular cleaning with special products is advised.
Can zinc be recycled at the end of its life?
VMZINC is 100% recyclable and in Western Europe approximately 99% of zinc roofs and walls are indeed recycled, even if you might have to wait a long time to do it. This recycled zinc is then used for many things; galvanising, brass production, cosmetics and obviously new zinc sheets.
Is zinc appropriate for use on buildings outside Europe with very different climates?
VMZINC started to sell zinc to many countries around the world in the middle of the 19th century and this has continued into the 21st century. We have offices in many parts of the world and work regularly with local architects and installers. A webinar of around the world in 80 zinc projects is available
Can zinc be used for gutters, downpipes and with other roofing materials?
It can. Since VMZINC started rolling zinc in 1837, and even before, zinc has been used widely as material for gutters, downpipes and flashings on tile and slate roofs. ANTHRA-ZINC was initially launched in 1978 as a flashing material to compliment slate roofs.
How does zinc perform with regards to fire?
As zinc is a metal it is non-combustible. VMZINC has been tested to Australian Standards for material combustibility. Our material has been tested to AS/NZ 1530.1 - Combustibility Test for Building Materials, and AS/NZ 1530.3 - Simultaneous Determination of Ignitability, flame propagation, heat release and smoke release. Interlocking Panels and Cassettes are installed onto metal rails and are non-combustible façade techniques. Standing Seam, Flat Lock Panels and other continuous support techniques can be installed onto metal support for non-combustible building applications. Trapezoidal or Corrugated metal profiles replace plywood as the support substrate.
What warranties are offered on zinc?
As VMZINC has been used as a roofing material since 1837 we have an excellent understanding of the durability of the material. Standard VMZINC Material Warranty issued for material installed by VMZINC recommended contractors, installed to VMZINC recommendations is 20 years. We can now offer a material warranty of up to 50 years on a project by project basis. It is obviously critical that the zinc roof or wall is designed and installed correctly. Traditional standing seam roofing and cladding should be installed by a recognised metal roofing contractor and not by a general builder.
What is the natural patina?
Zinc reacts with water to form zinc hydroxide; this then reacts with Co2 to form the stable compound zinc hydroxycarbonate. The amount of time required for formation of the patina from Natural zinc will depend on the exposure of the zinc to water. A low slope roof may only require 3 years whereas a protected soffit may require over 10 years exposure.
What is white rust?
When zinc is exposed to too much water and not enough Co2 the stable grey patina will not form leaving the unstable zinc hydroxide which is commonly referred to as white rust.
Does zinc need protecting from external attacks?
No, zinc does not require any particular protection because it protects itself by forming a patina when it comes into contact with the oxygen and carbon dioxide in the atmosphere. Nevertheless, the use of pre-weathered zinc may be recommended in particularly aggressive environments such as industrialised areas or industrialised marine environments.
Does zinc pollute?
The amount of zinc in the environment does not present a risk to ecosystems because it is within a range of concentrations that are optimal for life.
Is zinc harmful to human health or living organisms?
No, zinc is not harmful to human health or living organisms, nor is it toxic in itself since it is necessary, and indeed essential, in small quantities for all living organisms whether they are human, vegetable or animal. They draw it from their food in order to ensure that their metabolism functions properly. Zinc is essential for human health, for example for growth and for the protection of the skin. It also plays an important role in the development of the brain, foetal development, immune functions, sense of taste, sense of smell, etc.
What are the main factors that influence the zinc corrosion rate?
The corrosion rate of an exposed rolled zinc surface is influenced by:
- sulphur dioxide (SO2), typically found in very urbanised or industrialised atmospheres.
- chlorides, essentially present in a marine atmosphere.
- the slope and direction of the exposed surface.
- surface treatments.
SO2 has the greatest impact: it is very soluble in rainwater which it acidifies. It attacks the protective layer of zinc hydroxycarbonate (patina) to form a soluble zinc sulphate which is washed off by rainwater. The corrosion rate of zinc is thus higher in highly industrialised areas.
Can zinc be used in a marine atmosphere?
Zinc is a metal that performs extremely well in coastal environments and our normal warranties are valid for these locations. However, as zinc is a natural non painted metal it can react with its external environment including air with a high salt content. When this salty air lands on surfaces such as roofs the rainwater rinses the salt off, however on un-rinsed surfaces such as some facades and soffits this rinsing effect maybe very limited. For these surfaces within 1km of the sea, permanent staining resulting from salt exposure, is likely. The staining will also be more visible on a very dark grey surface such as ANTHRA-ZINC.
All finishes can be considered in marine areas though VMZINC strongly recommends non-coated natural patina zinc finishes such as QUARTZ-ZINC (light grey pre-weathered), Natural zinc (mill finish), and AZENGAR (natural textured zinc). These finishes will patina naturally and are the most resilient and durable options. Azengar in particular is the most suitable finish for marine areas due to its light colour, and textured surface disguising the appearance of salt deposits.
Is zinc compatible with all materials?
The only materials with which zinc are not compatible in the case of direct contact are:
- metals such as copper, brass, steel, cast iron and chrome.
- wood with an acid pH, for example: chestnut, oak, larch, birch, Douglas fir, and red cedar.
- cement and plaster.
- bitumen, even water from a bituminous roof should not run over a zinc roof.
However, if precautions are taken to avoid direct contact, zinc can be used with all types of substructures.
What are the main environmental guidelines for the building industry worldwide?
There are 4, each with its own specifications. The purpose of all four is to optimise the environmental performance of buildings.
Why is rolled zinc an asset in sustainable development?
Zinc is an asset with regard to environmental guidelines because some of its properties contribute to protecting natural resources, reducing greenhouse gases and limiting costs related to waste management and building maintenance. Moreover, the variety of textures and finishes allow the building to blend into its surroundings, which is also an asset. These properties are:
- low energy consumption for the production of rolled zinc.
- high recovery and reuse rate (95%)
- extremely durable.
Where is zinc found in the environment?
Rocks, many minerals, soil and water and the air naturally contain variable concentrations of zinc. There is an average of 80g of zinc per ton in the earth's crust. In some areas of the earth's crust, as a result of geological and geochemical processes, there are particularly high concentrations of zinc. In areas where the concentration of zinc is generally over 5% the ore is extracted.
Is there a risk of a zinc shortage in the future?
Taking into account the efforts made to recycle zinc and with an estimated 1,900 million tons of mining reserves, mankind's requirements for zinc will be met for over a century.
Do the zinc production plants pollute?
In industrialised countries, production plants have to obey very strict environmental regulations. The French plants are all committed to meeting ISO 14001 standards: the plant in Viviez obtained ISO 14001 environmental certification at the end of 2003. The Auby plant obtained this certification at the beginning of 2004 and the Bray-et-Lû plant obtained it in December 2004.
What are the main countries or regions where zinc is mined?
The main regions and countries where zinc ore is mined are:
- Asia (China, Kazakhstan, India and Japan) and Australia: 44%.
- North America (Canada, USA, Mexico) and South America (Peru, Bolivia, Brazil): 43%.
- Europe (Ireland, Poland, Spain): 10%.
- Africa (Morocco, Tunisia): 3%.
How much energy does zinc consume in comparison with the other metals used in the building industry?
Less energy is used to produce metallic zinc from ore or from recycled materials than for any other metal, such as aluminium, copper or stainless steel, used in the building industry.
In addition, less energy is used to transform zinc into rolled zinc than to process other metals. In fact, zinc's mechanical properties make it easier to roll and transform it into finished products for the building industry because these properties allow the zinc to be rolled at a low temperature compared to most other metals, thus reducing energy consumption.
What are the consequences of zinc deficiency on human health?
Zinc deficiency can cause serious health problems. Zinc is the 3rd most important trace element after magnesium and iron in the human body. As such, it participates in a great number of metabolic reactions. A lack of zinc in the diet can give rise to serious health problems such as skin problems, slower healing of wounds, reduced senses of taste and smell, increased risk of infection, retarded growth in children, mental lethargy, lack of appetite, hair loss, etc.
What is ecotoxicology?
Ecotoxicology is the science that studies the potential effects of various substances on ecosystems (ecosystem = biological community of interacting living organisms and their physical environment, for example: a tree trunk, a field, an ocean, etc). The science that studies the potential effects of various substances on human beings is called toxicology.
Do current zinc emissions present an ecotoxicological risk for the environment?
No, in the developed countries, current emissions of zinc into the environment present no ecotoxicological risk. Zinc is a natural element which is found throughout the environment (water, air, soil and rocks). Localised emissions of zinc into the environment can be from natural sources such as volcanic emissions, or be of human origin, for example: worn tires, atmospheric corrosion from galvanised steel or rolled zinc, from fertilisers and cattle fodder. In the developed countries, the amount of zinc measured in sensitive ecosystems shows that current emissions of zinc into the environment do not present any ecotoxicological risks because they are within the limits required for optimal conditions for life.
Is zinc a dangerous heavy metal like cadmium for example?
No, zinc is not a dangerous heavy metal in the same sense as cadmium for example. Metals are commonly divided into two groups: "heavy" metals (with a density of over 5 g/cm3 and light metals (with a density of less than 5 g/cm3). Since the density of zinc is slightly higher than 5 g/cm3 it can certainly be classified as a "heavy metal" because of its density. But the term "heavy metal" is often associated with "toxic". While this association is true for certain metals such as cadmium (if even a small quantity of these elements is inhaled, ingested or enters the human body through the skin, it can cause death or chronic or acute problems. This is not true for other metals such as zinc or copper. Zinc is not toxic because it is a trace element which is indispensable for all living organisms.
Do living organisms assimilate all the zinc emitted into the environment?
Not all the zinc emitted into the environment can be assimilated by living organisms. Only 10% in the ground and 30% in European rivers can be assimilated, the rest is in bound form and cannot be assimilated. Zinc that can be directly assimilated by living organisms is classified as "bio available".
What is the connection between sustainable development and environmental quality in the building industry?
In the areas of energy, waste and water the building industry has ecological (energy consumption, emission of greenhouse gases, production of waste, etc.), economic (energy costs, waste management costs, water treatment costs, creation of employment, etc.) and social (organisation of living space, sanitary conditions, durability, etc.) impacts.
These impacts are all related to the three fundamental pillars of the concept of sustainable development.
The environmental quality approach in the building industry, the aim of which is to reduce the negative impacts and optimise the positive impacts of this sector on the quality, environment and economy of society, is therefore a form of application of the concept of sustainable development in the building sector.
How does the use of zinc in building applications contribute to sustainable development?
The use of zinc in building applications contributes to sustainable development because:
- when zinc is used as a galvanising agent to coat steel it considerably lengthens the life span of steel products, reduces their maintenance costs and economises on the natural resources used to produce steel.
- zinc contributes to the durability of infrastructures and transportation systems on which modern society depends. Zinc thus contributes to social progress, 90% of all rolled zinc products are recovered. Natural resources are thus protected, there is less building waste in waste storage centres because of recycling, and jobs are created in the recycling market.
What are EPD's?
EPD's (Environmental Product Declarations) are internationally recognised document containing environmental information on a building product.
Surface Finishes
VMZINC is an elegant partner for many building materials. Available in 10 pre-weathered finishes as well as mill finish Natural Zinc. Highly flexible, malleable and durable. Zinc can be embossed, perforated and incorporate texture helping to create imaginative designs
Continuous Professional Development Presentation (CPD)
VMZINC offer a, RIBA accredited, CPD Seminar to architects and contractors.