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Technical regulation governing the arrangement of expansion joints
Technical Details
DIN 1053 Part 1 stipulates that expansion joints must be included in the facing wall. Expansion joints serve to compensate differences in deformation between the outer wall and the back-up masonry. Such differences are primarily attributable to temperature changes in the outer wall (summer / winter), as well as to creepage and shrinkage of the load-bearing back-up masonry. Model calculations (1) have yielded deformation differences of roughly 4 - 7 mm for a masonry height of 12 m.
Precise calculation of the distance between expansion joints (crack-free wall length) is difficult, due to the large number of influencing factors, such as paint, mechanical strength and mortar adhesion of the facing brick, intensity of sunlight to be expected, and many others. The following guideline values (1) are based on calculations, analyses and empirical results and are intended as a rough guide for the user.
View tables
| LR between expansion joints in the outer wall of double-leaf exterior masonry(*): | ||
| Wall structure | LR (m) between expansion joints in: | |
|---|---|---|
| Brick masonry 1) | Lime-sand masonry1) | |
| Double-leaf facework with air space | 10,00 - 12,00 | 6,00 - 8,00 |
| Double-leaf facework with air space and heat insulation | 10,00 - 12,00 | 6,00 - 8,00 |
| Double-leaf facework with core insulation | 10,00 - 12,00 | 5,00 - 6,00 |
| Double-Leaf facework with plaster coat | 10,00 - 12,00 | - |
| 1) the smaller distance must be selected for walls exposed to strong sunlight, with dark brick surfaces and / or facework with low weight. | ||
Main problem areas
Cracks can form if there is a concentration of stresses at individual points in the façade. Particular attention must be paid to the following points in this context:
• Parapet areas above supporting structures
• Differences in height between facework supports
• Connections over balcony slabs and canopy roofs
• Connection of doors and windows
It is not always possible to enforce the „pure theory“ when planning a façade. Consult our experienced engineers in cases of doubt. The danger of cracks forming can also be minimized by using masonry reinforcing strip (e.g. MOSO perforated strip) in addition to the provision of expansion joints.
Minimum width of expansion joints
The minimum width of expansion joints depends not only on the deformation to be expected, but also on the elastic resilience of the joint material. The following are recommended by:
For vertical joints:
15-20 mm (when using elastic sealant)
For horizontal joints:
15-30 mm (in general);
20-30 mm (for 12 m high wall and binder-bonded back-up masonry).