Most UK warehouse buildings constructed since 2000 use profiled steel metal roofs. The dominant systems are Kingspan composite panels (insulated steel), Tata Colorcoat HPS200 Ultra (single-skin profiled steel), Corus Twin Therm (insulated), and Ruukki RM (Finnish-engineered). All are excellent solar PV substrates with mature mounting solutions and well-understood warranty preservation.
Profiled steel mounting options
Mechanical fixing (most common pre-2020): system attaches to structural purlins beneath the steel cladding via bolts through the cladding. Lower dead load (5-10 kg/sqm) but penetrates the metal — requires waterproofing detail and may void manufacturer roof warranty. Ballasted (increasingly preferred 2020+): system uses concrete or steel weight to hold against wind uplift, no penetration. Higher dead load (15-20 kg/sqm) but preserves roof warranty entirely. Hybrid: small number of mechanical anchors plus ballast — preserves warranty in most cases.
Manufacturer warranty preservation
Kingspan, Tata, Corus, Ruukki warranties typically void on mechanical fixing through cladding. Each manufacturer has approved mounting partners and pre-engineered ballast solutions. We work with manufacturer technical teams on warranty preservation for every project. Where mechanical fixing is required (e.g. very high wind exposure), we obtain manufacturer pre-approval before fabrication.
Common issues with metal roofs
Roof age and condition: pre-2000 metal roofs may have corrosion or coating degradation requiring inspection. Solar mounting can extend or shorten roof life depending on installation quality. Thermal expansion: large roofs experience significant thermal expansion — mounting must accommodate movement. Cold bridging: insulated metal panel roofs (Kingspan, Corus Twin Therm) require careful roof penetration design to avoid thermal bridging in cold storage applications.
Common questions about metal roof solar
Will solar void our metal roof warranty?
Mechanical fixing typically does void the warranty. Ballasted mounting preserves warranty. We work with manufacturer technical teams (Kingspan, Tata, Corus, Ruukki) on warranty preservation for every project.
How old can a metal roof be for solar?
Roofs up to 25 years old are typically suitable. Beyond that, coating degradation and corrosion may require inspection or refurbishment. Pre-2000 buildings sometimes need re-roof to modern profiled steel before PV can be added.
What about insulated panel roofs (Kingspan)?
Kingspan composite panels (insulated steel) are excellent PV substrates — ballasted mounting preserves panel integrity. Cold storage applications require careful roof penetration design to avoid thermal bridging. We use proven ballasted systems and avoid mechanical fixings unless the roof has been re-engineered for solar mounting.