single lock standing seam

Double lock standing seam

What is standing seam?

Standing seam is a single folded or double folded seam.

  • The use of profiling and seaming machines for the closure of longitudinal seam joints significantly reduces installation time.
  • The low height of the seams (25 mm) contributes to the modernity, lightness and regularity of the roof and facade, while highlighting its architectural purpose. When dealing with more complex designs this system presents a more technologically advanced appearance.

Characteristics of this technique

  • Zinc plus is installed on minimum thickness 19mm plywood over a breathable anti abrasive building paper.
  • A 40 mm continuous air gap must be left clear beneath the plywood, on all roof pitches.
  • Continuous ventilation openings are made at the top and bottom.

Surface aspects: QUARTZ-ZINC in Zinc Plus/ ANTHRA-ZINC in Zinc Plus / PIGMENTO in Zinc Plus


What is Zinc plus?

Zinc plus is VMZINC coated on the underside with a protective layer (VMZINC patent).

  • Allows the use of an incompatible roof deck.
  • Zinc plus products can be bent, folded or profiled without any surface change (similar to VMZINC products) and thus allow the exact methods of laying.
Height of the seam  25 mm
Maximum centre to centre distance 600 mm
Thickness 0,7 - 0,8 mm
Length Up to 13 m
Simplicité de pose Traditional system widely used throughout the world,
Discrete Flexibility and discreet joints making it suitable for every architectural design,
Technicité Maximum wind resistance,
Simplicité de pose Fast and easy installation making it a cost effective solution.
  • All types of roofs.
  • All shapes: flat, curved, concave, convex, conical, domes.
  • Pitches: Minimum pitch 3° (5%).

The support must be :

  • 19 mm plywood rigid and continuous, with a minimum 40 mm ventilation cavity that is unobstructed.
  • Rest on at least 3 bearing structure elements.
  • Have no protruding elements on the support.

Stages to install Double lock standing seam:

1 Laying the panel on the structure.
The L profile of the preceding panel and the clips that have been fastened to the panel and fixed to the structure are covered by the U of the next panel, avoiding stresses and lateral traction.
2 Installation of clips.
Number of clips for roofing (depends on the climate zone - contact us for further information)

Transversal junctions
When the length of the roof slope exceeds the maximum recommended length, it is necessary to join the sheets using transversal junctions. Several techniques exist depending on the pitch of the roof.

Step (or drip)
For pitches of 3° (5%) or more: The step height will be a minimum of 8 cm for Standing Seam.



Double welt
For pitches of 8° (15%) or more:
The double welt can be used in the standing seam technique for pitches of 15% and above. The minimum length of the overlap is 200 mm with a securing clip at the top.
The overlap should be increased according to climatic conditions such as wind and rain.



Single welt
For pitches > 25° (47%) or more:
The single welt or single lock cross-welt with an overlap of 50 mm can be adopted for pitches greater than 47% (25°) in the standing seam technique.
VMZINC recommends using the double welt over the single welt for standing seam techniques as it provides greater water resistance.



Fixing System

  • Clips have a dual function:
    • Ensuring the mechanical resistance of the entire roof.
    • Allowing free expansion of the metal.

    The clips from VMZINC are made of 304 stainless steel. The thickness of the fixing clip is 0.5 mm.
    The sliding clips have a moving component, which is 0.4 mm thick, and a 70-mm long slot to allow free movement of the panel from VMZINC under expansion and contraction.
    The sliding component of these clips must be carefully positioned within the slot at the time of installation. In general, the sliding component is positioned in the middle of the slot.
    The clips resistance to tearing is 50 daN.
    It is recommended that screws be used to secure the clips.
    Three screws per sliding clip is recommended. The use of nails offers significantly less resistance, but in the event of using nails contractors are advised to use ring shank nails.

  • Centre to centre distance between clips
    • 330 mm on the main part of the roof.
    • 165 mm at the perimeter on a distance equal to 1/8 of the projected roof (Ra1), minimum of 3 clips to ensure wind resistance.

If your project is higher than 30 meters and/or if it is in an area where wind speed is higher than 170 km/h once a year, please consult VMZINC.


Fixed clip positions
Use the chart below to determine the location of the fixing clips on your project.



For more information, please contact VMZINC.

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