FORGET THE MYTHS: GET THE FACTS ABOUT VM ZINC®:

Myth #1 - Ventilated installation is required

While it is true that traditional zinc is installed in ventilated applications, VM ZINC® offers VM ZINC® PLUS. This innovative product provides a protective coating on the underside to allow installation directly over slip sheets and roof decks, not unlike the installation of copper.

Myth #2 - Cold weather installation can cause cracking

Some will warn against using zinc below 45º F. What they don't tell you is that it is the temperature of the metal, not the air temperature at the installation site, which is important. Hence, if you store the material in a proper location (such as a heated warehouse), you can use it straight away.

Myth #3 - Thermal expansion of zinc is a problem

All metals expand and contract with changes in temperature. In designing our fixing systems, VM ZINC® utilizes a series of fixed and sliding clips to manage these changes. In fact, due to designing for expansion, VM ZINC® installations can have significantly less pillowing or oil-canning than manufacturers that utilize rigid fixing systems. VM ZINC® even supplies these stainless steel clips.

Myth #4 - Zinc is not widely used or proven

Zinc has a long standing track record in almost every environment imaginable, from the harsh coastal environments of New England to the alpine climates of Colorado and everything in between. In fact, zinc has been the number one roofing material in Paris for over 150 years. Today 80% of all roofs in Paris still use zinc.

Myth #5 - Underside corrosion can limit durability

VM ZINC® PLUS solves any possible problems with underside corrosion. A thick protective coating on the underside prevents contact with any trapped moisture. Like all VM ZINC® products the durability is exceptional - with proper installation, 30 -100 years can be achieved in virtually any environment including heavy industrial or coastal applications. Backside coating of zinc should be 60 microns thick and/or have an abrasion resistance of 140 liters per ASTM D-968, method A.

Myth #6 - Zinc is a heavy metal and not environmentally sound

Heavy metals are not poisonous, per se. Gold is a heavy metal and is still used in dental work. In fact, zinc is an additive to a healthy diet. Its lifespan and recyclability make it an environmentally sound decision. Zinc refining utilizes less energy than the refining of copper, aluminum, or steel.

Contact With Other Metals

There are no issues with zinc in combination with metals other than copper and mild steel.
When zinc contacts copper in the presence of an electrolyte (such as water) a galvanic reaction would lead to corrosion of the zinc and subsequent failure of the roof or wall. Run off from a copper surface to a zinc surface must be avoided under all circumstances.

Zinc in contact with mild steel is not desirable either, due to similar electron transfers between the metal resulting in zinc deterioration and corrosion.

In general, water should not be allowed to run from a higher potential metal to a metal with a lower one. Install metals in the following order (from top to bottom)

• Aluminum
• Zinc
• Galvalume
• Lead
• Copper

Zinc and Wood

When laying zinc on a wooden substrate you must make sure that you use ZINC PLUS, because the wood might contain acids that are dangerous to the zinc. Between VM ZINC® and the wood there should also be a slip sheet (Roofshield or Wallshield).

You should also stay away from tanins and phenolic glues. The zinc would be protected by the coating of the ZINC PLUS, but the wood itself does not absorb moisture, so you would trap moisture in your roof complex, which suffice to say is not a good thing.

We also recommend staying away from OSB or chip-board. There is no issue with compatibility but this material is simply not strong enough for to hold the screws that secure the metal.

You should be very aware though that some trees might have a negative effect on the zinc. For instance rainwater dripping from red cedar on zinc would contain sap from the tree. This sap could stain or even corrode the zinc. You should in general keep the following in mind:

Flatness

The issue of flatness (often referred to as oil-canning when referencing there is a lack of flatness) is a consideration with zinc as with other metals.

It needs to be understood that waviness does not affect the performance of a zinc roof or wall, but rather it is an aesthetic concern. Zinc is a softer metal than other metals, typically used on roofs or walls. There are ways to reduce such unusual unwelcome oil-canning. Umicore has strict internal production parameters.

The fabrication of the panel should be done by the manufacturer as opposed to field-forming. While field-forming by the contractor is possible with their own equipment, the quality control of the panel. If the panel we control the flatness.

Another important factor is the thickness of the material. Certainly higher gauge zinc is more expensive per square foot because it has more material. If you apply this to the installed costs, the additional costs are negligible. It is recommended using at least 0.7mm (0.027") zinc in roof applications, better yet, 0.8mm (0.032"). For most wall applications it is recommended to use 1.0mm (0.039") or even 1.5mm (0.059"). As a rule of thumb. Keep in mind, the thicker the gage, the larger the panel gets.

The next factor is the sub construction. Zinc being a malleable material will adapt itself to the support. If for instance the deck that supports a VM ZINC® roof panel is wavy, the chances are high that the zinc roof will follow that form. If the studs and plywood substrate on the wall are not aligned, the zinc will have a tendency to become wavy.

Like any other metal zinc will expand and contract with changes in temperature. Zinc expands 1/64" per foot under a temperature variation of 212ºF. This is slightly less than Aluminum or lead, but more than copper, steel or stainless steel. Umicore addresses this issue by utilizing sliding clips, which allow for this expansion and contraction.

The awarded contractor/installer should be aware of all this, should be properly trained and best case already have experience with zinc. Contact your VM ZINC® rep or one of our offices for a list of contractors in the area.
Discuss your concerns with us early in the design phase. By involving us in the design phase of the project, we will be able to assist you with detail recommendations in such a way that your requirements can be met.

Maintenance / Cleaning

VM ZINC® is a low-maintenance natural material.

Fingerprints

• Due to human chemical makeup fingerprints are quite visible on zinc. The installer should be advised (in the specification) to either wear gloves and long sleeved shirts in order to minimize prints. All VM ZINC® panels and sheets come standard with a protective film. We recommend removing the film as quickly as possible following installation. To remove fingerprints, we recommend cleaning the zinc with a mineral oil, distributed by Umicore for this purpose. Not all mineral oils are compatible with zinc, so we suggest you only use oils approved for VM ZINC®.

Grease and Dirt

• If grease or dirt should accumulate on the zinc during the installation, it can be gently removed with a clean cotton cloth. One must not use any detergents or abrasives. If you can’t wait for the next rainfall, then use warm tap water to clean.

Scratches

• If a scratch appears, the zinc will heal itself overtime. If the scratch is extremely deep you may have to consider replacing that particular panel.

Protective Film

• As indicated our panels and sheets come standard with a heavy duty protective film. This film shall be kept in place until the sheet metal installation is complete. After completion remove the film promptly. While it is UV resistant for 3 months, it prevents the weathering process and you may end up with a non-homogenous surface if not all the film gets removed at the same time.

Extreme Climates / Atmospheric Conditions

VM ZINC® has been successfully installed in a variety of climates including alpine, maritime, and as well as desert environments. Extreme climates swings from hot to cold, dry to humid do not affect the performance of an installed VM ZINC® system.

During installation in a cold atmosphere, zinc may become cold brittle. Zinc should not be colder than 45ºF or 7ºC or it may crack. Typical tricks of the trade are heated seamers or to keep the zinc under a heated blanket if installed in winter conditions. Also zinc should be kept in a dry and heated environment. The A/E/D should consider making these recommendations part of the specification.

In an extremely dry environment, the weathering process will be significantly slower. Due to the lack of water or relative humidity, scratches will take longer to heal. If NATURAL ZINC (not preweathered VM ZINC®) the patination process will take longer than for areas where normal rainfall is being experienced.

Weathering / Patination / Corrosion

The development of a patina protects the zinc from excessive metal removal rates. The patina forms when the zinc is in contact with water and carbon dioxide from the atmosphere. Technically, the patina is a layer of zinc-hydroxy carbonate. This layer is dark grey in color. In marine environments the composition of the layer will be different. The salt content in the air or water will form Zinc Oxychloride, which has a whitish aspect to it. The white residues will normally be washed with rain. However in dryer salt environments it may remain. While this has minimal affect on the performance of VM ZINC® it is an aesthetic concern. In salt environments, we do not recommend applying ANTHRA ZINC® (our black zinc) directly at the sea shore.

If water sits on the zinc or is in constant contact with the metal without airflow, the zinc will corrode. While this usually does not happen on the face of installed material, it can occur on the underside of installed material. It can also happen during storage, which is why it is crucial to follow our recommendations for transportation and storage.

In a Rain Screen wall, this is not an issue because you have a constant airflow behind the zinc that would dry the water out. On a roof where you typically do not have an air cavity behind the zinc, use ZINC PLUS material. ZINC PLUS is a polymer coating that protects the zinc’s backside from underside corrosion tested according to ASTM 968. In wall applications where the metal is installed directly on wooden supports or is in permanent contact with wood (no air barrier) we strongly recommend the use of ZINC PLUS. This typically is only the case for angled seamed wall panels. Interlocking panels, even if installed on wood support have enough airflow by design. Keep in mind that moisture can enter the substructure from the inside of the building by way of condensation.

Metallurgy

VM ZINC® as a building material is actually an alloy. It is 99.995% pure zinc, produced by an electrolytic process, alloyed with traces of copper and titanium added in controlled quantities. These elements reduce brittleness when cold and increase the re-crystallization point. The re-crystallization point is important for soldering and indicates that coarse grain formation does not start below 572° F (300° C).

European standard EN 1179 governs the production of 99.995% electrolytic zinc and EN 988 governs the production of the rolled alloy.

Copper raises the mechanical resistance of the alloy making it harder and stronger. It also controls the color of the natural protective patina that is created as the zinc weathers.

Titanium increases the creep resistance, permitting far greater thermal expansion and contraction of the material without causing metal fatigue.

European standard EN 988 defines the following quantities of titanium, copper, and aluminum in the production of high-quality rolled zinc:

• Titanium: 0.06% minimum - 0.2% maximum
• Copper: 0.08% minimum - 1.0% maximum
• Aluminum: 0.015% maximum

VM ZINC® Weights and Thicknesses

VM ZINC® Mechanical & Technical Specifications