Guidelines for processing and normalisation

Material temperature

The material temperature of titanium zinc should preferably be at least 7°C. This prevents that the material will crack or fracture during folding and profiling. To achieve this temperature a heat source can be used.

Roof pitch

From a structural point of view, the design of a roof covered with titanium zinc is essentially the same as that of a façade, varying from 3° to 90°. Flat or almost flat roofs with a pitch of less than 3° should, if possible, not be covered with titanium zinc unless the surface area of the roof is less than 15 m², for example over dormer windows and canopy roofs.

  • the NedZink system provides a rain tight cladding for straight roofs and external walls with a pitch between 7° en 90°
  • the double standing seam system provides a rain tight roof and facade covering where the pitch is in excess of 3°, preferably 7°
  • the roll cap system is suitable for large and small roofs with a pitch of at least 3°, preferably 7° and as a façade cladding
  • the lozenge system is used for covering large and small surfaces. The minimum pitch is 25°, of 18° when the vertex of the lozenge is soldered.

Ventilation cavity

The ventilation cavity must be open to the external air via ventilation apertures at the lowest and highest points of the façade or roof. The air must be able to flow between apertures without major obstacles. The required dimensions for the gap and the apertures are detailed in the following table:

Table

          Pitch     

minimum width of ventilation

minimum cross-section of ventilation apertures (top and bottom) per m² of roof surface area

      less than 3°
      3°  – 20°
     20° and over

20 cm
10 cm
 5 cm

25 cm²
20 cm²
10 cm²

Where a higher moisture level is present, as is the case with a temperature of 20°C and a relative humidity level of 60% (vapour pressure > Ps = 1400 Pa) the minimum pitch recommended is 7°.

Bay length

NedZink system

Bays may be joined to form lengths of up to 6 meters.
Lengths of up to 12 meters may only be produced for roof covering.
Joining system bays by means of soldering. 

Standing seam system

Roof: The bay length should not exceed 10 meters.

If the length exceeds a transverse joint is needed to allow thermal movement.
The actual type depends on the pitch of the roof. At this joint, part of the profile is removed, to prevent the welt becoming too thick.

Façade: Vertically installed we recommend a bay width of maximum 500 mm.

Bay length maximum 6 meters for handling.
Horizontally installed we recommend a bay width of maximum 430 mm.
Bay length maximum 5 meters for handling.

Roll cap system

The first bay is hooked into the eave apron. The lower edges of this First bay are bent to the correct angle of the roof pitch. The selected length of the first bay is frequently 1 – 1.5 meters. This bay, together with the soldered sheet insert, can be produced in the workshop in advance. A bay consisting of a single length or several lengths soldered together must not exceed 10 meters in length to allow for thermal movement. The bays can be connected by soldering or seaming. The cappings are soldered together up to a maximum length of 10 meters.

Windload

The requirements for wind loads, which a Dutch building construction must meet, are described in the NEN standards of the Dutch Standardization Institute NEN. Fully supported constructions with traditional systems, like standing seam and roll cap, will particularly be subject to wind suction. For cantilevered structures wind pressure, weight and consequently the deflection of the material are involved. Besides this the method of attachment and the chosen system are important. The occurring wind suction on a wall or roof section depends on the height and shape of the building.

Wind suction means a by wind uniformly distributed wind suction in Newton per m², perpendicular to a surface facing down from the wind. The calculation of wind suction, depending on the altitude and the differences between the wind areas in the Netherlands is registered in a NEN norm.

Zinc roof coverings and wall claddings are attached to the substructure by means of clips. The clips of the standing seam and roll cap system are located on the longitudinal seam between the bays. The clips of the lozenge system are locked in the folded edges of each lozenge. For flat roofs with soldered sheet coverings the clips are placed underneath the soldered joint. The clips are often made of titanium zinc, but can also be made of stainless steel, galvanized steel or aluminium. Roof and wall coverings that consist of bays mainly are attached with fixed and sliding clips.