New regulations for flat clay lintels

››1 Marginal conditions for flat lintels with multi-layer overlying masonry and 71 mm or 113 mm high tension booms

››2 Marginal conditions for flat lintels with single-layer overlying masonry and 113 mm high tension booms

››3 Examples of tension boom types regulated in [4]

››4 Flat lintel of clay unit masonry with overlying masonry without mortaring of the vertical joints according to [4]

››5 Requirements for thermal insulating lintels for wall thicknesses of 300 to 490 mm. Insulating material according to DIN EN 13162,
DIN EN 13163, DIN EN 13164, DIN EN 13165 or DIN EN 13166. Building material class at least normally inflammable

››6 Possible arrangements of tension booms for flat lintels with thermal insulation provided on site by the builder (wall thicknesses 300 and
365 mm). Insulating material according to DIN EN 13162,
DIN EN 13163, DIN EN 13164, DIN EN 13165 or DIN EN 13166. Building material class at least normally inflammable

››7 Possible arrangements of tension booms for flat lintels with thermal insulation provided on site by the builder (wall thicknesses 42.5 and 49.0 cm). Insulating material according to DIN EN 13162,
DIN EN 13163, DIN EN 13164, DIN EN 13165 or DIN EN 13166. Building material class at least normally inflammable

››8 Tentative experiments for deflection of flat lintels with single-layer overlying masonry; execution of the vertical joints and overview

››9 Load deflection curve of flat lintels with single-layer overlying masonry; clear span 2.25 m, bearing depth 125 mm

››10 Test specimen, lintel height 375 mm [10]

In Germany flat lintels were regulated since 1977 in the flat lintel guideline specification and supplementary technical approvals. With the conversion of the design to the partial safety concept a revision was necessary in this respect. Load-bearing flat lintels with tension booms made of special-purpose clay units are regulated in future through technical approvals. For many years masonry with non-mortared vertical joints has been the construction method mainly used in Ger-many. However, in the area of overlying masonry above flat lintels, the mortaring of the vertical joints was prescribed so far. For the first time a further new technical approval allows the execution of non-bearing overlying masonry above flat lintels with large-format clay units without mortaring of the vertical joints.

1 Introduction

In the draft of the master list of technical building regulations of September 2008 the guideline specification for flat lintels [1] dating back to 1977 is intended for deletion and is therefore facing its annulment by the building supervisory authorities.

In a working group made up of representatives from the building authorities, industry and science the guideline was revised and adjusted to the partial safety concept. Unfortunately the planned implementation in a joint guideline of the Deutsche Gesellschaft für Mauerwerkbau (DGfM) was not possible because in some cases...