The load transfer facing shells
must be placed on the same support over the entire length of the entire surface. When changing the material of the support (e.g. concrete to
stainless steel brackets), vertical movement joints (also expansion joints) must be arranged.
Anoverhang of the facing shell of a maximum of 25 mm with a wall thickness of 115 mm and a maximum of 15 mm with a wall thickness of 90 mm is considered to be fully supported.
If the contact area is further below the contact area with a wall thickness of 115 mm – up to 38 mm is possible – the load must be transferred every two floors. Otherwise, facing shells up to twelve metres high are possible without load transfer, provided that the façade geometry allows this.
If the wall is 90 mm thick, horizontal support must be provided at intervals of about six metres. In buildings with two full storeys and a gable triangle up to four metres, no additional load transfer is necessary. A static proof can be used to deviate from the above rule. Facing shells with a thickness of 90 mm may be made up to a height of 20 m above ground
Thecrack formation
The movement sequences should always be coordinated. Corbels rigidly transfer the forces of the supporting structure into the facing shell. The supporting structure, especially if it is made of concrete, has a different deformation than the facing shell. Facing shells can heat up to 80°C in appropriate sunlight, but the supporting structure remains cool. Tensions are then the result, which then show up in the form of cracks in the facing shell. These cracks can damage the facing masonry over time due to the effect of water in combination with frost.
The joint width
of movement joints usually has a minimum width of 15 mm. In the case of horizontal load transfer, the material widths of the bracket must be taken into account. The visible horizontal joint can then be significantly wider than 15 mm. Building separation joints must be taken into account in the facing shell and are usually significantly larger than 15 mm.
When
dividing movement joints, it is essential to take into account the stone format, the stone colour and the wall structure. Dark clinker bricks heat up more than light ones. Large stone formats have a lower proportion of joints than small-unit clinker bricks, and the few joints in large formats must be able to absorb more deformations. In the case of the air layer, heat is dissipated via the chimney effect, but not in the case of core-insulated wall structures.
There are no specific regulations on the spacing of vertical movement joints, only recommendations are made in the standards. In practice, lengths of about eight meters to a maximum of twelve meters have proven to be effective, depending on the stone format, color, construction and cardinal direction.
Vertical movement joints must always be arranged at corners. The wall panels are guided around the corner a maximum of 240 mm. As a rule, the head width is the measure of the movement joint. Wall panels with approximately equal leg lengths of a maximum of five metres can also be designed at the corners without vertical movement joints. The division of the movement joints offers a large number of possibilities. Horizontal movement joints result from the technical conditions, while in the case of vertical movement joints, the façade geometry and the design idea of the planner play a major role. In this case, we always recommend talking to the planner and the consultant.
The movement
joints must be closed as permanently as possible. This is usually done with permanent plastic masses or with movement joint swelling tapes. With the latter, the color selection is small. As a rule, permanent plastic joints can be adapted to the colour of the existing mortar joint as far as possible and can also be sanded. Permanent plastic joints must be renewed approximately every 10-15 years, depending on the quality of the workmanship. When planning movement joints, it is therefore important to ensure that there are as few joints as possible.
in cooperation with GIMA:
