Basic principals for installation
VMZINC products have to be used and installed by recognized professionals in compliance with VMZINC technical specifications and industry standards in force in the country where the product is installed.
It is important to respects conditions of use and maintenance.
VMZINC in relation with other materials
Various metals can be classified in accordance with their reactivity potentials, relative to the normal hydrogen electrode.
If two metals are in contact, the metal with the higher potential in the electrochemical ranking decomposes the metal with the lower potential and, by accelerating corrosion, destroys it after a certain time.
In practical terms, a certain number of bimetal contacts are acceptable while others must be avoided. This is particularly important when installing lightning protection. In addition, water must never be allowed to run from a higher potential metal to a lower one: the water can contain charged ions which would accelerate the removal rate of the weaker metal.
Acceptable contact between alternative metals and zinc
| Metals | Comments |
|---|---|
| Lead | There are no associated problems with this metal. |
| Aluminium | Although a lower potential, it develops a passive layer on its surfacehas a similar protective coating, thus the two metals have very similar potentials, eliminating in building application conditions any the risk of corrosion. |
| Galvanized Steel | Galvanization coats the steel with a thin film of zinc. This zinc-zinc contact poses no problems. |
| Stainless Steel | Contact with Aaustenitic stainless steel and lead or tin-coated ferritic stainless steel is permissible. |
Unacceptable contact metals
- Copper.
- Steel (Non galvanized).
Protecting the VMZINC during installation
As a general rule please avoid walking on VMZINC after installation even if the zinc is protected by film. However, when necessary, it is advised that ladders designed for this purpose are used and security footwear suitable for use on a slippery surface worn. Please ensure that all safety rules on the worksite are complied with at all times and that a safety harness is used. For works being performed near to the VMZINC (plastering, jointing, cementing, etc) the VMZINC already installed must be protected. Furthermore, it must be ensured that this protection does not block the aeration of the upper surface of the VMZINC.
Removing the protective film of VMZINC roofing or cladding
VMZINC protective film
VMZINC is a non painted product with a natural metal finish. This means that the surface is susceptible to staining and marking during the construction process. It is for this reason that pre-weathered VMZINC is supplied with a protective film unless requested otherwise.
The film is designed to protect the zinc from dust and dirt which are common on all construction sites. It cannot protect the zinc from physical impacts.
Removal of the protective film
The film must be removed within 2 months of the zinc being installed. If no works are to be carried out within the vicinity of the finished zinc work we would recommend that the film is removed as soon as possible. Pre-made zinc panels should always be stored with the film intact and in a dry and ventilated environment.
The film must not be partially removed during installation for the remaining film to be removed at a later date, as this is likely to allow water to become trapped between the zinc and the partially removed film resulting in staining. It should be noted that most stains are very difficult to remove.
If fully filmed sheets are being used to form panels, which may make it difficult to remove the film after installation, the film can be scored by using a piece of zinc (greatly reduces scratching of the preweathering).
This must be done on an area of the panel where water cannot build up, ie in the reveal of a cassette panel and not on the face of a panel. The scoring must also be done so as to leave a clean well adhered edge to the film.
Foot Traffic
Normal use implies traffic reduced to a strict minimum for normal maintenance defined above and other work, such as: chimney sweeping, installation and servicing of aerials, etc. It is advisable to take all the precautions and useful provisions necessary so as not to cause: Any punching of the flat parts or deformation of the joints, roll capping, roof vents, etc. For this, it is advisable to install walkways; Any deterioration of the pre-weathered layer. In the case where technical equipment requiring frequent inspections (air conditioning, for example) is installed on the roof, certain adaptive arrangements such as walkways should be considered. During installation, maintenance, or use of roofing which contains skylights, or other accessories made of glass fiber reinforced polyester, care should be taken not to press directly on these materials. Scaffolding, platforms, planks or ladders should be used.
Expansion and contraction
All VMZINC systems and installation recommendations (link to 11 documentations), take into account the need for expansion and contraction. VMZINC's thermal expansion coefficient is 0.22mm per metre and per degree Celsius. During installation at an ambient temperature of 20°C, the temperature difference between 20°C and 80°C and 20°C and -30°C should be taken into account. For a panel measuring 10m in length: expansion to be provided for: 0.022mm x 10 x 60 or 13.2mm contraction to be provided for: 0.022mm x 10 x 50 or 11.0 mm.
Work temperature
Zinc can be used in all climates. However, to avoid micro-cracking when folding the Natural, pre-weathered QUARTZ-ZINC and ANTHRA-ZINC zinc the temperature, of the metal, must be at least 7°C. The PIGMENTO series must have a temperature of at least 10° C (temperature of the metal) before being bent or profiled. It should also be noted that the minimum panel bending radius for the Pigmento range is zinc thickness x 4. For other finishes the bending radius is zinc thickness x 2.
Installation of external elements
The following elements: parabolic antennas, lightning rods and solar panels are often installed on rooftops. To find a solution, you should think about the way in which a VMZINC roofing system operates and take into account its requirement to expand and extract.
VMZINC and climatic constraints
Rain fall quantity and wind load pressure and suction should be taken into account together as both are main constraints for roof and wall cladding design.
Rain constraints
Attention must be paid in particular to:
- joining methods,
- overlapping of roofing elements,
- junctions at uneven points, chimneys,
- elevator shaft extrusions,
- skylights and dormer windows,
- up stand flashing against walls,
- valley strips.
Wind load for building applications
It is the responsibility of the design team/architect to determine loads for the building resulting from wind action in accordance with the applicable national standards. This type of standard defines:
- reference speeds or pressures to be taken into consideration according to the geographical distribution of winds in the area,
- formula and methods required for the engineer to calculate wind pressure on the building according to its geometry, as well as the influence of the surrounding topography on the variation of wind speeds.
VMZINC roof and wall cladding systems offer large possibility to respond to various climatic constraints.
The conditions of use such as low-pitch roof/ high UV/ marine combination should also be taken in consideration when choosing a VMZINC surface finishings. It is the responsibility of the design team/architect to verify if the VMZINC surface aspects are adapted (esthetic, weathering) to the expected conditions of use.