Expansion sleeves are necessary to absorb the expansion and contraction of the roof gutter.
An expansion device must always be supported by a bracket.

In practice we distinguish between two types of expansion pieces, mechanical expansion
(see figure 3.1.10) and rubber expansion (see figure 3.1.11).

A mechanical expansion has an expansion joint and a separation slide on the left and right.

A rubber expansion is fitted with a rubber galvanised expansion piece and a zinc beaded edge.