Embedded in the valley of the Reppischtal, the new replacement building Lettenmatt consists of 8 houses surrounding an elongated inner courtyard. Seven of the eight houses are connected by an underground car park. The houses consist of a basement, a ground floor, two upper floors and an attic floor including terraces. All buildings have a full basement, except for the loggias and entrance areas on the ground floor. Around 90 mixed and partially age-appropriate residential units are planned and realised. Commercial space is also planned for the ground floor of the building on Poststrasse, including a restaurant and community room. Three shelters with a total of 206 shelter spaces will be built in the development.

The buildings are constructed in solid construction with a material mix of concrete and load-bearing masonry. Slender steel-concrete composite columns are also used. During planning and construction, special attention had to be paid to the existing high-lying aquifer. A cantilevered sheet pile box was created for the construction of the basement floors and the groundwater was lowered to below the excavation floor using filter wells. The installations in the groundwater were minimised using a shallow foundation with local ground improvements and the meticulous adaptation of the underground building geometry. To protect the aquifer, the subsoil was also improved with gravel instead of lean concrete and compensation volumes were created by installing rubble packs in the backfill area.