Seam

Characteristics Crimping process Documents

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Houses in Astilleros, Santander. Blue pigmented zinc roof with seam (caption)

Characteristics

The seam system is the most flexible that we use, perfectly valid for flat, sloped, curved and undefined shape roofs. This is a very versatile system that has demonstrated its worth for centuries in countries where this type of panelling is traditional.

This is a system that covers the roof by seaming sheets of metal together lengthways on site to form a watertight joint with hidden fastenings.

Their aesthetics are subtle, imprinting fine lines every half metre, more or less, particularly the roof from the ridge to the eaves, normally in the direction that water will flow. It gives the panelling direction and a sensation of lightness.

Quinta Metálica uses technical details and finishes on the ends of the joints, unions with other materials and meetings with the edges of the roof that highlight this sensation of lightness.

In addition, these same details let the metal dilate in response to every day thermal changes. This is essential to make sure that the panelling lasts a long time. Quinta Metálica uses the same details developed and tested in countries such as Germany, Belgium, France and England to guarantee that the roofs can dilate without any problems.

Tecma Centre, Alzira. Seam Joint Roofs

The seam system for roofs is installed in two different varieties: the 'long strip' variety and the 'traditional' metal sheet variety. Normally, for economic reasons, the usual variety is 'long strips' which covers the roof with very long metal plates, with one entire strip between the eaves and the ridge. However, some material is only available in limited length metal strips, and this is therefore fitted in the 'traditional' variety of metal sheets. The joint used to bring the crossways metal sheets together depends on the slope of the roof and is crimped along the lengthways seam.

Crimping process

The 'female' side of the last plate is fixed with a side piece screwed to the direct support.

A new plate is fitted on to the last one

The 'male' side is folded around the fold of the 'female' side, crimping the two sheets of metal together. The result is called an "angle seam" and we use it mainly to cover facades, although it also works for roofs with a slope over 25º.

Finally, the process is completed by folding the horizontal fold vertically to get a double seam

Example diagram of seamed panelling on non ventilated roof:

Hunting lodge, Bitaño, Durango, Vizcaya. Seam roof (caption)

Summary of seam systems for roofs
Characteristics		Comments
Possible metals	Copper, zinc, stainless steel, titanium
Aesthetics	Provides direction to the roof	Normally the joints follow the direction that water will flow, but this is not essential
Shapes covered	Any shape	Flat, steeply sloped, vaulted, spherical, amorphous
Sealing	Minimum nominal recommended slope; unsealed 6º, sealed 3º	The recommended minimum for each project depends on the length of the plates and the maximum intensity of the rainfall that the roof might receive
Fastening method	Indirect, with fixed and mobile side pieces on the joints, held to the support with screws or rivets	Normally every 300 to 400mm. Mobile side pieces that let the metal dilate lengthways along the joints
Dominant joint size (seam)	A rib 25 mm high x 5 wide
Plate size (joint spacing)	From 430 to 600mm wide x (nominally) 10m long maximum	From 430 to 600mm wide x (nominally) 10m long maximum. Depends on the wind force and the metal to be used and its thickness
Support required	Over the whole surface and reasonably smooth. Ventilated or non ventilated	Board, rigid insulation, screed, sandwich panels, corrugated metal
Cost	Economical	The cheapest system for roofs
System variations	Traditional for sheet metal	The variation with long strips is normally used
	Traditional for sheet metal	Only with materials not available on coil
	Angle seam	Only valid for roofs with slopes over 25º
Auxiliary equipment on site	Perimeter protection of the roof. Additional safety line when the roof slope makes it necessary	A safety line is necessary if a falling person might slide down the roof. Quinta Metálica studies whether this is necessary, case by case