(57) By corrugating a deformable sheet material for use in roof tightening to a continuous
S-shape forming waves with troughs, the diameter (a) of which is greater that their
slit aperture (b), and by providing the crests of the waves and the external side
of the valleys with transverse stampings (4), the sheet can be given substantially
the same stretchability and workability as a conventional plane sheet lead and can
be used in replacement thereof, for example for tightening the connection between
a skylight flashing and a non-plane roofing.
The sheet material may consist wholly of lead or another metal, in which case a sheet
of smaller thickness than conventional sheet lead can be used, which gives an improved
workability, so that assembling can be carried out without hammering with the resulting
variations in thickness.
The sheet material may, alternatively, be carried out in the form of a sandwich consisting
of an aluminium foil (1) and a tension reducing and stabilizing protective layer which
may comprise an adhesive paste (3) and a cover foil (2) on one side of the foil (1)
or layers of elastomeric material such as naturel or synthetic rubber on one side
or both sides of the foil.
In the latter embodiment, the sheet material may be given the shape of a strip, in
one longitudinal side of which a strip- or thread-shaped plumb may be inserted for
the purpose of weighing down the strip.
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