In case of the timber-framed building in Pfeifergasse 9 in Nürnberg with asymmetric building construction with a gabled roof with one roof side reaching down to the first floor and inadequate reinforcement of the supporting structure, the constructional problem was to restore the visibility of the timber frame construction, to observe the German Energy Conservation Regulations (EnEV) of 2009, and to consider the aspects of the preservation of historic buildings and the simultaneous stabilization of the building. The applied typha board material fulfills all these requirements. The exemplary material application was funded by the German Environmental Foundation (DBU) and the Bavarian State Office for the Preservation of Historical Monuments (Bayerisches Landesamt für Denkmalpflege).
With the typha board an extremely slender exterior wall construction of a thickness of 16 cm plus 4 cm plaster with wall heating is realized. Due to the simple processability and inherent stiffness the material could be adjusted to the irregular inclined walls. To achieve resistance to wind typha joint swelling mortar was applied to the joints and cracks in the wood by means of a cartouche press. The external plaster was directly applied to the board material as especially diffusion-open three-layer plaster of calcareous tuff sand and chalk and reinforced by the umbrella-shaped seed of the cattail.
The Fraunhofer IBP investigated the suitability of the wall structure over a measuring period of 1.5 years and determined a thermal transmittance (U-value) for the infill of 0.26 W/m²K. The U-value of the whole building (infill and timber construction) is 0.31 W/m²K. The low level of moisture applied by the swelling mortar and plaster dried out fast to a constant moisture contents in the wooden supports of below 20 M.-%.