Standing seam system
The standing seam system provides a rain-tight roof and façade covering where the pitch is in excess of 3°, preferably > 7°. The single standing seam is used for roofs with a pitch steeper than 25° and for façades. For roofs with a pitch angle lower than 25° the double standing folded seam is used.
The standing seam system makes it possible for a roof or façade to be covered with titanium zinc quickly and at reasonable cost. This is because preformed bays are used, and the seams are folded mechanically, reducing manual folding to a minimum. The preformed bays are supplied in custom-made sizes and are locked together on site with a single or double fold, by machine or by hand. Aside from straight bays, curved (convex and concave) and tapering bays can be made easily. The bays are secured to the substructure by means of fixed and sliding clips (see figure 5.1.1).
With a standing seam roof, the zinc bays are connected in the longitudinal direction with so-called (double) standing seam. The material thickness is 0.80 mm. The allowable bay width is determined by the wind load and the height of the roof. The advised bay width varies from 330 mm to 530 mm. The advised maximum bay length is 10 meters (thermal movement: 20 mm). When making a selection, think about handling the bays.
The standing seam can consist of a single or double connection. A single connection forms a less effective water seal and may therefore only be used on roofs with a pitch angle larger than 25°. With fixed clips the cladding is fixed over a one-meter length. Sliding clips are used for the remaining length of the roof bay. The location of the fixed clips depends on the pitch angle of the roof. The relationship between the location of the fixed clip and the pitch angle is shown in figure 5.1.6. Fixed clips ensure that the standing seam bays don’t slip. Bays up to 3 meters long can be fully secured with fixed clips. For lengths greater than 3 meters the bay is secured with fixed clips over a length of one meter, and the rest with sliding clips.
The standard height of a standing seam for a profiled seam is 25 mm. A seam height of 38 mm is sometimes used to accentuate shadow formation. The higher seam also offers improved rain proofing in the case of windy conditions.
To promote the rain proofing aspect of a standing seam roof, sealing tape can be affixed between the seams. This is also recommended for unventilated systems that pose a risk of leakage.
Fastening the clips
The bays are secured to the substructure by means of fixed and sliding clips (see figure 5.14, fixed and sliding clip). The fixed clips secure the standing seam bay and the sliding clips make longitudinal expansion possible. The clip is secured over the lowest standing seam bay and on the sub-construction. Then the top standing seam bay is placed over this and folded shut.
The standing seam system must be fully supported by unplaned, untreated wooden boards at least 23 mm thick, not tongue and grooved, with gaps of at least 5 mm.
The space between the boards can be larger depending on the pitch of the roof, i.e.
roof pitch up to 45º 5 – 10 mm
roof pitch from 45º – 70º 5 – 50 mm
roof pitch from 70º – 90º 5 – 100 mm
The construction requirements are also important in this. Use galvanised nails with a zinc-layer thickness of at least 20 microns or AISI 304 stainless steel for fastening.
Below are some examples of typical details for roofi ng. These details outline the standard situation and serve as a guideline for applying the standing seam system on roof structures.