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Fixings for insulated walls (ETICS)

There are several concept for installing a steel wire rope on an insulated wall, these can be found on the page insulation. The fixings for walls insulated with an ETICS / EIFS system can be found on this page here, as well as possible statical problems and similar points that need to be considered.

>>> Price list.

Mounts installed while the facade is being insulated

Ideally (but rarely), the facade greening is factored in at the same time as the building construction is being planned, or before construction is finished. The anchors for the trellis can then be built while the façade is being externally insulated. FassadenGrün offers two fittings for this case:

Mounts for later installation

Most often, the decision to have climbing plants grow on the façade is made after the building is built and the external insulation (ETICS) has been installed and sealed. The fittings listed here are designed to be installed on a finished façade.

  • XP 12XX7 for ETICS up to 18 cm

  • XP 12XX9 for ETICS up to 24 (30) cm

  • WM 12XX8 for ETICS up to 12 (14) cm

  • WM 12XX9 for ETICS up to 22 cm; easy installation

  • WM 12XX2 for ETICS up to 6 cm for light loads

  • WM 12XX4 for ETICS up to 12 cm for light / medium loads

  • WM 12XX6 for ETICS up to 16 cm on hard insulation

  • WH 08555 direct installation in the ETICS panels

Structural Problems

Mounts carrying tensioned cables are subjected to greater loads and stress than fastners for rigid metal or wooden grid trellises (details under wire rope mounts). Cable mounts for insulation are almost always fixed ito the load-bearing wall, i.e. with composite mortar behind the insulation layer. With thicker insulation panels it becomes more difficult to make the anchorage sufficiently secure. Three structural problems are described here, along with solutions.

 

Shaft of a cable mount as a fixed 'cantilever'
Shaft of a cable mount as a fixed 'cantilever'

Problem 1: Deformation (Bending)

The threaded shaft on our mounts and anchor bolts reaches as far as the cable carrier end (all the way up to the cross-head where the wire rope is being attached). The thicker the insulation panel in which the bolt is mounted, the more it will bend under the load of the cables and climbing plant until it buckles under the weight! The bolt is secured in the masonry under the insulation panels (in the load-bearing wall) and not held by the insulation. So, with a 10 cm insulation and with a distance of 7 cm between the cables and the façade, the length of the cantilever is actually 17 cm in total!

 

Bending of a rope holder under load (here exaggerated); green circle = bending point
Bending of a rope holder under weight of cable system and plant (here exaggerated); green circle = bending point

Shortening the threaded bolt

The most obvious solution for more stability is to first shorten the mount (the anchor bolt) to reduce the leverage effect. Choose then reduced wall distances (between the wire rope and the facade). This principle is applied to many of our ETICS wall fixings.

Cable mount (with shorter wall distance) under load- lower bending point (less bending)
Cable mount (with shorter wall distance) under load- lower bending point (less bending)

Stronger (thicker) threaded bolt

The next measure would be to choose a bolt with a thicker thread diameter (e.g. M16 instead of M12), discouraging the bend-factor. Forming a support cone would also be a way to 'thicken' the anchor by distributing the load better.

Thicker shaft- reduced bending
Thicker shaft- reduced bending

Reduced load

The third possibility for more stability is to reduce the forces (loads) acting on the anchor mount by reducing the tension of the cables. For this reason, most of our wall mounts permit only 3 mm and 1.8 mm 'cables' (more like 'wire') for thick insulation. In this way, if an excessive load is applied, the weak point of the system is shifted from mount to rope, and the wire rope will break before the wall mount does.

Thinner cable relieves the load on the cable mount.
Thinner cable relieves the load on the cable mount.

Shorter cantilever: shifting the insertion (bending) point

The further (in the wall) the insertion point, the less elongation and leverage. With the length of the cantilever shorter, the beding-buckling point is shifted and reduced. We use small und large support cylinders for insertion in the insulation panels.

Bending point shifted to the left (green circle)
Bending point shifted to the left (green circle)

Supporting elements (fixation cylinders)

Instead of reinforcing the entire insulation layer with a solid panel, as shown in the diagram above, you can use individual small or large supporting bodies in the insulation board which will be screwed to the facade. From a mechanical engineering perspective, these supports act as cantilevers. Due to the tension in the wire ropes during storms, etc.. forces of up to 100 kg (statically correct: 1,000 N) arise there. This, multiplied by a wall distance / lever of 10 cm or 0.1 m creates so-called "bending moments" of about 100 Newton metres (Nm). This high bending moment load can be absorbed by the supporting bodies (fixation cylinders) without deformation, and redirected to the facade.

 

Attachment on external insulation under plaster (ETICS) with hardwood support bodies. The threaded mount then has a better lateral grip in the narrow hole.
Attachment on external insulation under plaster (ETICS) with hardwood support bodies. The threaded mount then has a better lateral grip in the narrow hole.

Problem 2: Stiff fixation

By design our wire rope mounts are "cantilever" in the sense of engineering mechanics. The tensioned  cables put loads of 250 kg or more (2.500 Newton) on the bolts, and with a wall distance of 10 cm the bending moment will be of 250 Nm (newton metres). This heavy bending load must be distributed in the wall without any deformation. This is difficult if the entry point is on the outer border of the insulation panel! The entry point has to be rigid.

Support tube for fastening in thermal insulation. The threaded shaft can 'break out' of its straight course due to the lack of lateral support, and then bend all the more to the left.
Support tube for fastening in thermal insulation. The threaded shaft can 'break out' of its straight course due to the lack of lateral support, and then bend all the more to the left.

Problem 3: "Yield stress"

A new problem arises by moving the bending point outward. The supporting bloc are pressed and screwed together so that tension is applied to the threaded shaft. The thinner a threaded bolt is, the more it will be elongated through this thension and from the load applied by the wire rope. The elongated shaft deforms and even wide wall mounts will deform and can't be fixed at their base.

Elongation of the fixed and tensioned threaded bolt (very exaggerated here)
Elongation of the fixed and tensioned threaded bolt (very exaggerated here)

Embedding of the threaded bolt

To avoid elongation, the threaded shaft can be partially embedded in composite mortar. The thread is cast in a bloc of epoxy resin. Lateral stability is thus increased, the threaded shaft can't move or bend inside the insulation panel. This solution is used in the "XP" wall mount series and described further in the page on supporting cones as well as in the combination method.

Threaded mount embedded in composite mortar (mortar cone); FassadenGrün cable mounts XP series
Threaded mount embedded in composite mortar (mortar cone); FassadenGrün cable mounts XP series

Support Bodies / Fixation Cylinders: Materials

The soluation favored by FassadenGrün is the use of supporting blocs. We use mainly blocs made of cellular glass that have a resistance of 2,500 Mpa, way more than the common PUR foam and its 500 Mpa or similar insulating foams. Even under high loads the cellular glass remains undeformed, as do the small treated hardwoord blocs that we use. Supporting blocs made of PUR foam or other inferior materials will deform in time and shouldn't be used.

Cable mount XP 12XX7 with support body made of foam glass
Cable mount XP 12XX7 with support body of foam glass

Cover plates

Our wire rope mounts for ETICS facade come with cover plates in different sizes that will cover the bored outer plaster layer. A foam sealing ring is also included. Depeding on the size of the wall mount, the cover plate will cover the bore hole, seal the façade and may even distribute some of the load onto the supporting bloc inside the insulation.

Cable mount XP12XX7, here assembled for 14 cm WDVS
Cable mount XP12XX7, here assembled for 14 cm WDVS

Thermal Break

Metals - such as the stainless steel we use -  are conducive of heat; way more than masonry, wood or plastics are. A metal shaft emebedded deep into the masonry may conduct heat out of the heated inner rooms. The total lost energy is small, but it is possible that on the inner wall the temperature drops punctually from 1 to 3 degrees Celsius, wich can theoretically lead to wet spots if the ambient humidity is high. In the worst case, this can lead to mold. It is therefore necessary to prevent thermal bridges in the masonry. 

All our wall anchors are sealed in the wall with composite mortar. The epoxy resin is not heat conducive and will prevent the loss of warmth.

Our thermal separator TT 12150 avoids any metal inside the masonry and all heat loss is prevented.

Two M12 threaded rods with and without thermal break (decoupling)
Two M12 threaded rods with and without thermal decoupling

Common solutions

Several solutions are commonly available for installation on ETICS panels, but these should not be used for wire rope trellises, as the loads on cables are much higher than what common fixings are designed to bear.