SFS UK Helps Project Teams Address Thermal Point Loss Early With Integrated Rainscreen Bracket Solutions
Peter Clarke, National Sales Manager, Rainscreen Subframe Systems, SFS UK Construction explains how his company's new approach combines bracket selection, thermal break technology and project-specific calculations, to support façade performance from the outset.
When discussing the thermal performance of a building envelope, the focus naturally falls on insulation thickness, glazing specifications and airtightness strategies. Yet there is another element within the façade build-up that can have a significant influence on overall performance, despite often receiving far less attention: the rainscreen bracket.
A typical rainscreen façade can contain hundreds, sometimes thousands, of brackets. Individually, each one may seem insignificant. Collectively, however, they can have a noticeable impact on a wall's thermal performance and ultimately determine whether a project achieves its target U-value. As building regulations and client expectations continue to place greater emphasis on energy efficiency, thermal point loss is becoming an increasingly important consideration for architects, façade consultants and contractors. In my view, bracket selection should therefore be addressed during the design stage rather than being left until the subframe specification is finalised.
Understanding thermal point loss
U-values remain the primary benchmark for measuring thermal performance, yet they only tell part of the story. Wherever a rainscreen bracket penetrates insulation to connect the façade system back to the structure, there is potential for heat transfer. This is known as thermal point loss. The contribution of each bracket is measured through its point thermal transmittance, commonly referred to as an χ value. These values are then incorporated into the corrected U-value calculation for the external wall. This is where material selection becomes critical.
Aluminium brackets offer strength, durability and versatility but, as a highly conductive material, aluminium can contribute to thermal bridging. Traditionally, isolator pads have been used between the bracket and substrate primarily to reduce the risk of bimetallic corrosion, although they may also contribute to thermal performance depending on the wall build-up. Stainless steel, by comparison, has a lower thermal conductivity. This means it can help reduce thermal point losses while also providing excellent corrosion resistance without the need for an isolator between the bracket and substrate. The key point is that every project is different. Bracket selection should not be based solely on structural requirements; it should also consider the thermal implications across the entire façade build-up.
A joined-up approach to bracket specification
At SFS, we have brought these considerations together within our NVELOPE® Thermal Solutions range, providing designers with aluminium and stainless-steel bracket options alongside the patented NVELOPE® Thermal Pad. Rather than treating thermal performance as a separate consideration, the aim is to support a more integrated approach to façade design.
The NVELOPE® Thermal Pad is supplied pre-fitted to the bracket and has a thermal conductivity of 0.020 W/mK. As a non-compressible thermal break, it is designed to maintain its performance during installation, helping to minimise the difference between calculated and installed performance when correctly specified and fitted. The pad adds 10mm to the cladding zone, a dimension that should be established at an early stage to avoid later design changes.
For projects where reducing thermal point loss is a key driver, the NVELOPE® NVS + Thermal solution combines stainless steel brackets with the non-compressible thermal pad to support lower calculated external wall U-values. Aluminium options, including the VB + Thermal and HB + Thermal systems, utilise the same thermal pad technology to help minimise heat loss while providing the advantages associated with aluminium systems. VB + Thermal brackets are manufactured from aluminium with an average recycled content of 60%, supporting wider sustainability objectives.
Beyond thermal performance, reaction-to-fire performance must also be carefully considered. The aluminium and stainless-steel brackets are classified A1 to BS EN 13501-1, while the NVELOPE® Thermal Pad achieves an A2-s1,d0 classification. As always, fire resistance requirements must be assessed as part of the complete tested system and verified through the appropriate technical channels.
Why early-stage calculations matter
One of the biggest challenges facing project teams is obtaining accurate thermal data early enough in the design process to make informed decisions. Too often, thermal corrections are applied later in the project lifecycle, potentially creating a scenario where insulation depths or façade details require revision to meet performance targets. This can introduce additional costs, programme delays and unnecessary complexity. That is why project-specific calculations are increasingly important.
Through our SFS Project Builder platform, which forms part of the ConnectSuite® digital ecosystem, project teams can submit key design information including substrate type, building height, façade loads, cladding zone requirements, and preferred bracket options. Our technical specialists then assess the project and provide a package of supporting information including indicative static load calculations,
NBS specifications and thermal performance data. Where required, χ values are calculated for the project's specific wall build-up using three-dimensional modelling, rather than relying on generic assumptions or standard correction factors. This allows designers to understand more accurately how bracket selection will influence thermal performance and can also help identify opportunities to optimise insulation thicknesses and potentially reduce costs.
It is important to emphasise that these calculations are intended to support the design team rather than replace their responsibilities. Any outputs should be independently reviewed and verified by appropriately qualified professionals as part of the wider design process.
Getting the details right
The rainscreen bracket will never be the most visible part of a façade. Once the cladding is installed, it disappears from view entirely. However, its influence on building performance remains. By addressing thermal point loss at the design stage, selecting the most appropriate bracket solution, confirming cladding zone requirements and understanding the associated χ values, project teams can make more informed decisions from the outset.
In an industry where every aspect of a building's thermal performance is under increasing scrutiny, the smallest details often have the greatest influence. The bracket may be hidden behind the façade but getting it right early can make a meaningful contribution to the long-term performance of the entire wall system.
For more information about SFS UK's NVELOPE® Thermal Solutions range and Project Builder platform, visit https://uk.sfs.com/ or call 0330 0555888.