Lörmecketurm

This tower on the Plackweg in the Arnsberg Forest between Warstein and Meschede gives hikers the opportunity to see the surrounding panorama from the viewing platform at a height of 34m above the treetops. This extends over the Arnsberg Forest and the Sauerland region as well as over the entire Hellweg region far into the Münsterland region.

A rotational hyperboloid was chosen as the geometry. This form combines the advantages of an open, filigree architecture with an efficient and timber-structured load-bearing structure. Due to the openness, the tower does not compete as a monumental mass against the existing nature, but emphasizes in its lightness and its construction the presence of the forest. The tower is rotationally symmetrical, as are its three platforms - at the top and twice at the thirds points. It does not give the user a preferred viewing direction.

The tower has a mean diameter of about 7m at the head as well as at the base and a total height of about 35m. In the middle, the average diameter is about 5m. The widening towards the base increases stability, while the widening towards the top increases the viewing plateau.

The geometry of the structure is appropriate for timber construction, as only straight round bars and articulated connections are used. With the round milled Douglas fir wood, only domestic sawn timber was used.

The entrance results from the omission of a base point with two subsequent rods. Thus, the tower has only 23 nodes at the base. This does not affect the load-bearing capacity. The structure is in the long to transfer the incoming loads through the large number of nodal connections.

The spiral staircase with landings and a central center support is completely decoupled from the envelope. For load transfer, the stair is braced to the envelope with prestressed tension rods. This allows the stair to be independent of the geometry of the envelope and to have a uniform height.

The timbers were pressure impregnated. The details are designed in such a way that all end faces are structurally protected from precipitation by covering as well as the drill holes with sealing washers.

The slots for inserting the flat bars are beveled so that no water remains on the timbers. From swelling and shrinkage of the timbers, cracks appear in the wood. To control the cracks, there is a saw cut on the underside of the timbers in the longitudinal direction. With these measures, the service life is significantly increased.

With the chosen design, as described in relation to the entrance area, the load-bearing capacity is not compromised if a single bar fails. This opens up the possibility of replacing individual, damaged load-bearing members at any time without great effort and without assembly supports. The construction is thus also largely protected against vandalism. For graffiti, the construction has proved uninteresting due to the lack of surfaces.