Now and then one finds damaged tension ropes on greenings. Usually it is the mounts that are affected, which may be bent or torn off the wall at the highest point of the flexural buckling load. This might be due to errors during assembly (poor mounting), but unfortunately, the problem often lies in the planning, or even in the design/construction of the mounts, attributable to the respective manufacturer. As a result of slow plant growth, such problems usually do not occur until the warranty period has been exceeded. Here you can learn about damage patterns, explanations of their causes, and how FassadenGrün prevents damage to its own products.
Some tensioning rope/cable systems are only zinc-coated (galvanised) and rather designed for indoor use: Mounted outside, they soon rust. Such elements are hardly qualified for facade greening. But stainless steel mounts too can rust; for instance, in the case of curtain systems. Oftentimes, discolourations occur because the respective stainless steel is not sufficiently rust-proof for outdoor use.
If curtain systems (for example) are used, which are designed for light loads only, structural damage is inevitable. Due to the heavy loads in wall greening caused by storms, wet leaves, fruits and so forth, the mounts will soon be torn out. Even mounts which are actually designed for metal bars will give out when clamping rope, because the tension is much higher using ropes instead of bars. Vandalism damage, in turn, occurs when improperly planned (horizontal) tension ropes give a "climbing possibility" for a vandal.
In the case of climbing systems, it is necessary to address their suitability with certain plants. FassadenGrün-systems are divided into five construction styles. With the help of the climbing plants pages on this site, an assignment to particular construction styles is possible. This prevents overloading.
As a rule, tightly tensioned ropes/cables should not be overgrown with and thus "strangled" by climbing plants. Otherwise, the resulting tensile stresses of up to 500 kilograms (3 mm rope) or 1,000 kilograms (4 mm rope) will destroy the mounts. FassadenGrün addresses the difficulty of finding the right climbing technique-- i.e "parallel rooting" / "stock arrangement" in the case of vulnerable/tempermental climbers and strong twiners (Chinese wisteria, bittersweet, knotweed). Please have a look at the respective pages on climbing plants.
Tensioning ropes are multilaterally stressed. This starts with the pre-stress/preload; later, the load of the leaves, fruits, and stems can quickly reach 10 kilograms per square metre and even double in the case of wet leaves (after rain). Extreme loads of 50 kg / m² result from icing... that is, from multiple freezings and wind pressure, especially at higher altitudes and on corners of buildings. Many providers of tensioning ropes fasten the ropes in such a way that the shock-like, very high tensile stresses are forcibly transferred to the mounts during peak loads (storm, icing, climbing or attempt at climbing, rebounding children’s balls, etc..). If these mounts are rigid and do not "spring," they cannot hold the loads and are quickly torn out. Mounts from FassadenGrün are only slightly pre-tensioned by hand (without rope tensioner) and thus, are not totally rigid but designed to be slightly springy. All cross mounts are equipped with an anti-slip protection, which means that overloads are only partially transmitted to the mounts. The ropes slip out slightly and can be tightened/ re-tensioned.
Greater wall clearance/distance operates like a lever and generates a high flexing buckling load that can bend or tear out the mount. FassadenGrün specifies exactly which wall distances are maximally feasible with which mounts.
These various problems occur the most: The emerging tensile stresses in a tensioned rope are underestimated, or not taken seriously; the shafts are in the range of the highest bending buckling load, so when entering the wall become interrupted or tapered in diameter and thus kink-prone; the fastening/doweling in the wall is not strong enough. Mounts from FassadenGrün do not have a shank break (disconnection/interruption) or tapering, and with strong dowels, they will be fastened deeply and securely into the wall.