Frequently asked questions

16 Questions

Where is zinc found?

Zinc is a part of nature. Most soils and many minerals on our planet contain zinc in varying amounts. Zinc occurs naturally in the air, water, and soil. The average natural proportion of zinc in the earth's crust is 70 mg/kg (dry weight) and can vary between 10 and 300 mg/kg depending on regional characteristics. Due to natural erosion processes such as weathering and erosion of rocks, soils, and sediments by wind and water, a small but important fraction of natural zinc is constantly moved and transported into the environment. Volcanic eruptions, forest fires, and particulate formation over the seas also contribute to the natural transport of zinc. These processes cause a zinc cycle in the environment that contributes to the natural background concentration in air, surface water, and soil. In the overall context, the natural zinc cycle is much more significant than that caused by humans. In addition, zinc, as an important trace element, is found in almost all living organisms, including plants, animals, and humans, where it performs important tasks for maintaining health. (IZA, 'Behavior of Zinc in the Environment - Essentiality and Bioavailability', 2014)

Zinc is an essential trace element. What does that mean for me?

Essential substances are considered those that are vital for the health of living beings but cannot be produced by the body itself. This means that these substances must be taken in through food. Zinc is an essential trace element for all living beings – including humans. It is significantly involved in many vital metabolic functions in our body. For example, zinc promotes the healing of skin wounds. During pregnancy, as well as in early childhood and puberty, the intake of zinc contributes to healthy development, and the immune system also needs zinc. A balanced diet usually provides sufficient zinc for humans. The need for an adult is about 10 to 15 milligrams of zinc per day. Since the body does not store zinc, excess zinc is excreted. Only at very high overdoses can zinc be harmful. ('Zinc in Human Health', edited by Lothar Rink, IOS Press 2011, online at:, ('Zinc: the metal of life', Kuljeet Kaur et al, in Comprehensive reviews in Food Science and Food Safety, Volume 13 (2014), online at:

Zinc is a heavy metal. Does that mean it is toxic?

Whether an element is considered a heavy metal or not, only says something about its physical density. This is of primary interest to material researchers and physicists, but does not imply anything about its significance for health and the environment. On the contrary: Zinc is an essential, that is indispensable, trace element for the human organism and is involved in many metabolic processes and maintaining health. ('Zinc in Human Health', edited by Lothar Rink, IOS Press 2011, online at:, ('Zinc: the metal of life', Kuljeet Kaur et al, in Comprehensive reviews in Food Science and Food Safety, Volume 13 (2014), online at: Looking at the group of heavy metals, which include elements with a density of more than 4.5 or 5 g/cm3, zinc, with a density of 7.14 g/cm3, is part of this group, but so are iron (7.87 g/cm3), silver (10.49 g/cm3), gold (19.32 g/cm3), and platinum (21.45 g/cm3). Iron, like zinc, is a vital trace element for humans and actively involved in oxygen transport in the blood, and gold, for example, is used as a dental replacement. Therefore, the statement that all heavy metals – and thus zinc – are fundamentally toxic is not correct.

I am planning to use zinc sheeting in the roof or facade area. What do I need to know?

Zinc can usually be used without problems in the construction sector. Under extreme climatic conditions or in special environmental protection areas, where the discharge of rainwater into a body of water is planned, local environmental or building authorities sometimes require additional information. In such cases, for example, the effect of the zinc surface on the environment can be calculated in advance in the planning phase using the computer program RainwaterCheck-ZINK, online at: We are happy to help you further – please contact us.

Zinc is an essential trace element. What does that mean for me?

In most cases, zinc can be used without any problems in the construction sector. Under extreme climatic conditions or in special environmental protection areas where the discharge of rainwater into a body of water is planned, local environmental or building authorities occasionally require additional information. In such cases, the impact of the zinc surface on the environment can, for example, be calculated in advance during the planning phase using the computer program RainwaterCheck-ZINK, available online at: We are happy to assist you further – please contact us.

What is the deal with the patina on the zinc surface?

Uncoated zinc forms a firmly adhering layer of zinc oxide and basic zinc carbonate on the surface due to weathering (carbon dioxide and precipitation). This very thin layer is called patina. The formation of the patina is indicated by the color change from the initially silvery-blank color of the titanium zinc to a matt, gray surface. The patina gradually grows into a uniform surface. (F. Porter, Zinc Handbook, Marcel Dekker, 1991) This very dense layer, which is 'self-healing' in case of superficial scratches, acts as long-term protection against corrosion and ensures that zinc sheet lasts a very long time – theoretically up to 200 years.

I am planning to use zinc sheet in roofing or facade areas. The rainwater should be infiltrated locally. What should I consider?

Local infiltration is done via the vegetated topsoil, swales, or trenches. In all these cases, zinc contained in the rainwater is bound during infiltration in the soil. Generally, the introduction of rainwater into groundwater does not require water law permission, as long as it is 'harmless'. Below infiltration facilities, the regulations of the Federal Soil Protection Ordinance are often applied to assess the soil-groundwater pathway. For zinc, an individual examination must be carried out from a value of 500 µg/l. According to the Groundwater Ordinance, zinc, like many other metals, generally belongs to the substances whose entry into groundwater should be limited. However, the Groundwater Ordinance does not specify a limit value. Often zinc is already present in groundwater because the surrounding rock contains zinc. There is also no limit value for zinc in the Drinking Water Ordinance. For local infiltration, a risk analysis or proof of compliance with environmental quality objectives in the planning phase can be calculated with the online program RegenwasserCheck-ZINK, online at: We are happy to help you further – please contact us.

What does zinc leaching mean?

Even though zinc is a very durable material, it is still attacked by air pollutants, such as sulfur dioxide or chlorides, so that minimal amounts of zinc are dissolved from the patina. The zinc is then washed off the surface by rain. As air pollution has significantly decreased over the last few decades, the leaching rates of zinc are now at their lowest level in the last 40 years. How much zinc is leached depends largely on the local air pollution (SO2), as well as on the amount of rain, roof slope and orientation, and the climate zone.

What happens to the dissolved zinc from rainwater in the soil after washing off?

Practical investigations have shown that soils have the ability to permanently bind zinc in the top few centimeters. Thus, it makes an active contribution to the supply chain of plants and living organisms in the soil-near area. Zinc binds to earth minerals (adsorption to oxides, silicic acid, carbonate, clay particles) or organic substances. As the pH of the soil increases (becoming 'more basic' or 'alkaline'), the soil can bind zinc better. Clay soils with a high pH value ('basic') have higher zinc contents, while sandy soils have lower zinc contents. (I. Odnevall Wallinder, 'Outdoor and Indoor Atmospheric Corrosion', 2002). This binding function of the soil is used for the construction of infiltration basins and trenches. A topsoil zone of 30 cm is used for retention, which usually occurs in the top 5-8 cm. The thickness of 30 cm serves to avoid 'breaking through' the functional layer and to compensate for construction tolerances.

Where can I find information about the legal regulations for the discharge of rainwater?

Information on zinc emissions in rainwater can be obtained from the Initiative ZINK, Düsseldorf, info(at), or the WVMetalle, Berlin, info(at) General regulations on handling rainwater are contained in the Water Resources Act (WHG) online at: More detailed explanations and permit requirements for rainwater treatment can be found in the state water laws or in individual rainwater exemption regulations of the federal states. Recommendations for handling rainwater, such as for the infiltration of rainwater, can be found in the worksheets ATV-A102 (Principles for the management and treatment of rainwater runoff for discharge into surface waters) and ATV-A138, Part 1 (Facilities for the infiltration of rainwater - under revision) of the German Association for Water Management, Wastewater and Waste.

What is meant by the term 'anthropogenic storage'?

Anthropogenic storage refers to a man-made deposit for raw materials – as opposed to natural occurrences, e.g., of ores in rock and soil. This also applies to zinc. Since construction zinc can be completely recycled, buildings with zinc roofing and facade cladding represent a valuable material store. This can be used in the future to reintroduce zinc into the material cycle through recycling and to process it into new, equivalent products. Zinc scraps do not have to be landfilled, thermally utilized, composted, or biologically degraded after use – they are naturally and simply reused.

Can zinc from anthropogenic stores replace mining in natural zinc deposits?

Even though over 95% of the zinc sheet metal used today is returned to the cycle, an anthropogenic store can supplement but not replace the mining of zinc ores. This is due to the long service life of zinc of up to 200 years and the resulting low scrap availability. Since only 5% of the primary energy is needed for zinc recycling compared to the extraction of zinc from ores, recycling zinc from anthropogenic stores significantly contributes to the protection of nature and climate. The ecological balance for zinc will improve in the future with the increasing use of scrap quantities after product use.

How will the anthropogenic zinc store develop?

Currently, in Germany, there are about 118 kg of zinc per inhabitant (9.4 million tonnes in 2014*), mainly present in galvanized metal products and as construction zinc. In the coming years, an increase of 1.22 kg of zinc per inhabitant is expected, so that the zinc stock will grow to about 12.9 million tonnes by 2050*. The anthropogenic store for zinc will thus grow and increasingly serve as a source of raw materials for recycling. *Source: 'Climate protection potentials of metal recycling and the anthropogenic metal store', M. Buchert et al., 2016, Öko-Institut. e.V.

The development plan prohibits the use of metal sheets for aesthetic reasons. Is that allowed?

In individual cases, the development plan may restrict the design freedom of an individual with precise justification. This can include the roof shape, the use of colors, or the use of certain building materials, including zinc sheet for facade cladding or roofing, in the development plan within the framework of a design statute. If certain materials are prescribed, e.g., to maintain the overall impression of a historically grown appearance, these specifications must be observed. Often, restrictions are made, e.g., permanently shiny metal surfaces are declared inadmissible. Zinc surfaces are often allowed in this case due to the expected blue-gray patina formation.

The development plan prohibits the use of uncoated metal sheets for environmental reasons. Is that legal?

No, zinc sheets are usually made of titanium zinc, which has a CE marking and is therefore fundamentally approved for construction applications. The CE marking confirms that the product complies with all applicable European regulations and is subject to the EU Construction Products Regulation. No further requirements may be imposed on products with CE marking. This is regulated in the Construction Products Regulation (BauPVO), according to which EU member states may not prohibit or hinder the use of CE-certified products. This also applies to the requirement for coatings, e.g., to prevent possible leaching of metal ions. The infiltration of rainwater, which has been derived from zinc surfaces, is fundamentally permitted. Furthermore, the stipulation of building materials in development plans is subject to state law. A prohibition of zinc sheets in development plans due to municipal regulations thus lacks a legal basis.

What can I do if I want to use zinc sheet on my house, but this is prohibited according to the development plan?

If this prohibition is justified by design guidelines, you must adhere to them. If other reasons are mentioned, indicating a prohibition of infiltration or reasons for water or environmental protection, you can address your building authority with a prepared letter that we have prepared for you here. Information on the legal background is outlined in the specialist article by lawyer Michael Halstenberg, which you can view here. You can also contact Initiative Zinc at the service number 0211 941906-73 or info(at) – we are happy to help!


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