House on the Elsensee sits on a 1,600 square meter plot directly on Lake Elsensee in the Kagel district of Grünheide, near Berlin. The project comprises 2 structures: a 2-story weekend house with a rectangular plan, and a single-story outbuilding to the north. augustinundfrank designed both in reinforced concrete as in-situ cast structures, with all walls, inside and out, left as exposed concrete.

The main house distributes the program across 2 floors in straightforward sequence. The ground floor holds the living room and kitchen; the upper floor holds the bedrooms and bathrooms. The floors are connected by a staircase inside a concrete cylinder, which also provides the lateral bracing for the building. The load-bearing ground floor supports use steel profiles rather than concrete columns. To prevent a thermal bridge at the junction between the concrete ceiling slab and the outer walls, the 2 are separated by an insulated joint, with the vertical loads transferred through shear-force-transmitting mandrels rather than a continuous connection. The ceiling slab is a WU waterproofed construction.

The outhouse contains a 2-car garage alongside a guest apartment with its own bathroom and a building services room. Its concrete shell uses the same seamless in-situ method as the main house, producing a material continuity between the 2 structures that reads as deliberate rather than economical.

The project belongs to a lineage of concrete weekend houses in the Brandenburg lakes region, where the material's weight and permanence sit in deliberate contrast to the temporary character of summer retreats. Here, the engineering is visible and honest, making no attempt to conceal the means by which the building holds itself up.