Combination with other systems

As a small company, "FassadenGrün" offers a rather "niche" range of ETICS fixings, specifically for climbing aids. However, there are now various modules on the ETICS fixings market that have "construction approval", and the question frequently arises as to whether these systems can be fitted with FassadenGrün brackets. Unfortunately, FassadenGrün is usually unable to grant approval in such cases, as whilst these systems are suitable for flange-type fixings, they are generally not designed for “cable brackets” and “lattice brackets”.

From a structural engineering perspective, cable and grid brackets are free-standing ‘cantilever arms’ which – depending on the wall clearance and length of the cantilever arm – can generate very high shear forces (bending buckling loads). These lead to elastic and plastic deformation of the bracket axis, potentially resulting in the loss of waterproofing against rainwater or even failure of the bracket due to buckling. These concerns are all the more relevant when thermoplastic materials are used for the pressure-bearing surface, as these then tend to exhibit the dreaded ‘creep’ under sustained load (deformation due to compression). Four cases are examined below.

A very well-known solution is the “FISCHER Thermax®”. However, there are now also similar products from other anchor manufacturers, e.g. TOX “Thermo Proof” and CELO “ResiTHERM®”... A single Thermax anchor is suitable for fixing our CABLE holders if the insulation thickness does not exceed 10–12 cm and holders of the simple, light or medium design are used. The distance between the cable and the wall must be limited to 5–6 cm. Other combinations should generally be avoided, as the non-thickened threaded rod of the “Thermax®” would otherwise bend too much and tear the front seal.

The decisive factor is the respective “lateral loads” permitted by the dowel manufacturer for a specific insulation thickness. A concrete example: For an assumed insulation layer (16 cm), the adhesive and render (2 cm) and the outer wall clearance of the façade green holder (e.g. 6 cm) must be added. In this example, that would amount to 24 cm. Often, no values are specified at all for these (high) thicknesses, or if they are, this is done whilst accepting a deflection of the anchor in the area of the wall penetration of 3–5 mm. The permissible lateral loads would then be approximately 25 kg (0.25 kN). As façade greenery already accounts for cable pre-tension of approx. 10 kg (0.1 kN), only approx. 15 kg (0.15 kN) per fixing point would then remain for the actual weight of the plants and all additional loads such as wind, dripping water, icing and vandalism. That is rather little! By way of comparison: Fassadengrün brackets are generally designed for lateral loads of approx. 50 kg (0.5 kN).

To absorb high loads, such as those from thicker (4 mm) ropes or awnings, SEVERAL Thermax units must be coupled and combined into dual or quad solutions. One or two threaded rods are then subjected to tensile stress, the others to compressive stress. However, Fassadengrün does not stock suitable ‘double brackets’; please enquire with the companies ‘Brandmeier’ or ‘Leffers’ (formerly ‘Schmitt Ranktechnik’).

A combination of “Thermax®” with our GRID brackets is, however, often possible, as the rigid structure of grids or bars means that lower continuous loads are generated. The expected shear forces are then lower, partly due to the absence of pre-tension.

If insulation anchors from manufacturers such as those described above are made of thermoplastics (nylon/polyamide with glass fibre reinforcement), their behaviour under continuous load must also be assessed when combined with Fassadengrün brackets. This relates to the issue of “creep” (see above).

Brackets from this group – now available from several system suppliers, such as “CELO ResiTHERM® 37” and “StoFix Iso-Bar” – feature a threaded rod reinforced with plastic in the area of the insulation, making them stiffer and less susceptible to bending. Such brackets have been developed and used for large-scale trellises since around 2000 by Thorwald Brandwein (company “Biotekt” – product brand “Polygrün”). And when combined with FassadenGrün products, these brackets should ideally be restricted to the intended use of “trellises”. In other words: our rods, trellises and trellis brackets can usually be approved for “EJOT® Iso-Bar” and similar products...

A combination with CABLE and CABLE holders from FassadenGrün is only possible, if at all, with insulation thicknesses of up to 14 cm. Brackets with an M12 shank (“heavy-duty” design) can be used if, deviating from our heavy-duty design, the distances between the cable and the wall are reduced to 5–6 cm. Other combinations must be ruled out because the deflection defined in the building authority approval for the "EJOT® Iso-Bar" in the area of the wall penetration (maximum 5 mm) may be exceeded, thereby compromising the waterproofing.

Companies such as "Dosteba" offer mounting cylinders and blocks made from thermoplastic (see above), which are more pressure-resistant than mineral wool and polystyrene (rigid EPS foam) and are designed for mounting "light" loads such as letterboxes. They are installed at the relevant fixing points in the insulation layer and, if necessary, also bonded to the substrate.

In mineral wool insulation, these components are generally not suitable for any of FassadenGrün’s mounting systems. However, if the insulation layer is made of polystyrene, the situation is different:

If the fixing takes place directly within the mounting cylinder, simple and lightweight cable and grid brackets may be used at the installer’s discretion. No written approval is required from FassadenGrün in this case, due to the minor nature of the installation.

If the mounting cylinders are drilled through and the respective threaded rod is fixed behind them, i.e. in the load-bearing wall substrate, FassadenGrün can grant approval for GRID brackets provided the insulation thickness does not exceed 14 cm. Larger washers must then be used to distribute the pressure over as large an area as possible on the mounting cylinders; please enquire. For this purpose, our WM 12XX6 bracket can be used, for example, but then with the KG 12004 grid head.

However, even in this case, no approval is granted for CABLE brackets.

Companies such as "Dosteba" also offer "heavy-duty brackets" for railings, canopies and awnings in insulated applications. Double brackets (see above) can be fixed using these where necessary, but single-axis brackets from FassadenGrün are generally not recommended due to the structural concerns outlined above.

Although such brackets and pressure pads have high insulation values, they have comparatively low compressive strengths of less than 1 MPa (such as, for example, rigid PU foam with a density of approx. 0.35 kg/dm³) and are therefore unsuitable for use with FassadenGrün cable brackets. It makes no difference whether an aluminium plate is additionally inserted into the “heavy-duty bracket” or whether the component is fixed to the load-bearing wall surface with four screws. The compressive strength values are too low for our cable holders, and the risk of “creep” (see above) cannot be ruled out. For comparison: compressive strength values of the pads used by FassadenGrün can be found here.

For the fixing of rods and grids, however, the heavy-duty brackets are perfectly suitable; in this case, FassadenGrün can grant approval provided the bracket is drilled through completely and the threaded rod is fixed to the load-bearing wall substrate (usually by bonding with composite mortar). For this purpose, our WM 12XX6 bracket can be used, for example, though in this case with the KG 12004 grid head.