Dowel anchors are air layer retaining anchors in the double skin masonry of a facade. They are hammered into drilled round holes in the base, usually the load-bearing masonry, with a special plastic expansion plug evenly distributed over the surface (basic rule 5 pcs. per square metre). These are intended to prevent the relatively narrow masonry facade (11.5 cm and less) from tilting and bulging. The length of the dowel anchors is chosen so that they bridge the insulation and air layer and at the end still protrude at least 50 mm into the horizontal joint of the facing layer with a 90° bend (bend length ≥ 25 mm). Instead of the bent end, more and more building authority approved anchor bolts with a corrugated end are being sold today, which saves the bending operation. In addition, the plastic anchor sleeves are firmly pre-mounted on the wire so that installation is very easy with the drive-in tube that is put over the wire during the setting process. The building authority approvals go up to a shell distance of 200 mm.
Modersohn also supplies air layer anchor systems for larger shell spacings. According to DIN EN 1996-2-NA, i.e. Part 2 of the national annex of Eurocode 6, `the masonry shells are to be connected by anchors made of stainless steel in accordance with the general building authority approval or by anchors made of stainless steel in accordance with DIN EN 845-1, the use of which is regulated in a general building authority approval`. This makes the use of stainless steel for the load-bearing and retaining anchors in the double-shell masonry façade compulsory.
Only the type of stainless steel from which the anchor is made was left open. These are increasingly the building authorities approved Lean Duplex Stainless Steels (D4), which have clear technical and price advantages over A4 qualities. Unlike the A4 steels, these steels are unfortunately magnetically attractive due to their ferritic structure, so that an inspection with a magnet at the construction site to determine that no galvanised normal steel has been processed is hardly possible.
Therefore, please have the technical test certificates, works certificates and approval documents handed over to you in advance without any gaps. The civil engineers and technicians of the Modersohn company can assist you in planning the right air layer anchors. Modersohn can cover your requirements at very short notice from a large stock range of different air layer anchor systems.