Horizontal slots in load-bearing walls without new structural analysis are only allowed by DIN 1053-1 in the area of 400mm at the top and 400mm at the buttom. In the area between no horizontal slots are allowed. The slot depth is defined:

Maximum Slot Depth for horizontal Slots wall depth with no length limitation with length limitation 1250mm 115mm or more 0 ! 0 ! 175mm or more 0 ! 25mm 240mm or more 15mm 25mm 300mm or more 20mm 30mm 365mm or more 20mm 30mm

Vertical slots in load-bearing walls without new structural analysis are only allowed by DIN 1053-1 with a slot depth and width al follows:

Maximum Slot Depth and Width for vertical Slots wall depth slot depth slot width 115mm or more 10mm 100mm 175mm or more 30mm 100mm 240mm or more 30mm 150mm 300mm or more 30mm 200mm 365mm or more 30mm 200mm

maximum allowed vertical slot in a load-bearing wall with a depth of 240mm without new structural analysis