Dimensioning Stainless Steel Wall Brackets for Façade Substructures

The basics of dimensioning: loads and load-bearing capacity

When dimensioning wall brackets, an engineer must account for two primary forces acting on the façade envelope:

• Vertical load (dead load): This is the self-weight of the cladding and the profiles  V=m⋅g V=m⋅g. This force is fully transferred by the fixed-point brackets, which are usually positioned at the top of a vertical profile.

• Horizontal load (wind load): Wind pressure (Wp)(Wp​) and wind suction (Ws)(Ws​) act perpendicular to the façade plane. Both fixed-point and sliding-point brackets are designed to absorb these dynamic wind loads.
  

Why stainless steel fixing systems?

Although aluminium has historically been widely used, stainless steel fixing systems — such as the IPEX 0848 or 0863 — offer superior advantages under heavy loads. Stainless steel has significantly higher stiffness and tensile strength, allowing for greater spans and a higher structural load-bearing capacity at larger projection depths.

Step-by-step dimensioning process

The dimensioning of a substructure for heavy façade cladding follows a strict technical procedure:

1. Substrate analysis

Determine the load-bearing capacity of the supporting wall, whether concrete, masonry, steel, or timber frame construction. For masonry and renovation projects, pull-out tests on site are often required to confirm the exact anchor resistance.

2. Calculation of projection depth

The projection depth of the bracket is determined by the insulation thickness plus the required ventilated cavity. Stainless steel wall brackets are available in versions ranging from 40 mm up to 400 mm.

3. Static calculation and spacing

Based on the project-specific wind loads in accordance with Eurocode 1, the maximum spacing between the brackets (h)(h) and between the vertical profiles (b)(b) is calculated.

4. Thermal correction (χ(χ-value)

Every wall bracket penetrating the insulation layer creates a point thermal bridge. During dimensioning, the χχ-value must be taken into account to calculate the actual net U-value of the façade. Stainless steel performs up to 10 times better than aluminium here due to its significantly lower thermal conductivity (about 15 W/mK versus about 160 W/mK), resulting in a much more favourable Rc-value for the overall façade.

Common design mistakes

Even experienced engineers sometimes make errors that negatively affect the façade’s service life or energy performance:

• Incorrect fixed/sliding ratio: The “floating” principle is not applied correctly. Each profile segment may have only one fixed point, allowing thermal expansion and contraction of the metal without causing deformation or binding in the façade construction.

• Ignoring corrosion classes: In maritime environments or under heavy industrial exposure, stainless steel A2 (304) is often insufficient. In such cases, stainless steel A4 (316) or duplex steel should be selected to guarantee a maintenance-free service life of 50 years.

• Underestimating point losses: Calculating with generic or theoretical U-values without taking the specific χχ-value of the selected bracket into account. This results in façades that, in practice, do not comply with strict BENG requirements.
  

Your engineering partner: IPEX Group

As a leading supplier of complete façade substructure systems, IPEX Group supports engineers, architects, and contractors with advanced services:

• Engineering expertise: Full project-specific structural calculations, including advice on optimal spacing and anchor selection.

• Thermal calculation: 3D modelling of wall brackets to determine the exact χχ-values and the actual net Rc-value of your façade design.

• Customisation & flexibility: With 126 standard variants and the option for customer-specific stamped parts, we offer a suitable solution for every construction detail.

Request a thermal calculation for your current project design.