Masonry needling
The term masonry needling comes from the construction industry and describes the connection of the two masonry shells of a double-shell outer wall with wire anchors, the so-called air layer anchors .
In the north of Germany, a two-shell masonry , consisting of the back masonry , the so-called supporting shell and the facing facade, the so-called weather shell , is often chosen. The external weather shell usually consists of an 11.5 cm thick facing facade made of facing bricks and is intended to protect against the effects of the weather, especially rain. An air layer (approx. 4 cm) and an insulation layer (approx. 10 cm) are often arranged between the facing facade and the supporting back wall with a wall thickness of 17.5 to 24 cm.
So that the slender, i.e. thin in relation to its height, the facing facade is stable, it is connected to the supporting shell behind it using a layer of air anchors. These wire anchors introduce tensile and compressive forces into the load-bearing back wall. They are inserted into the joints when the supporting shell is being built and are then available to the bricklayer when building the weather shell to bind it into the mortar layer. The number of air-layer anchors to be used is regulated in DIN 1053. As a rule, it is assumed that an amount of five pieces per square meter in the area and a line anchoring every 30 cm in the edge area and at the free edges.