A metal roof can be a suitable covering for an energy-efficient house, but it does not by itself determine the building's thermal performance. Rather than judging a product by its lambda value, check whether the design ensures continuity of insulation and airtightness across the whole assembly, especially at junctions at the eaves, walls, chimneys and windows. PIR boards above the rafters can reduce layer thickness, but they require proper support and fixing. Choose a board intended for the specific application, not a thin insulating facing. Leave the final layer build-up to the designer, who will select insulation thickness to suit the building's requirements.

After winter, examine the sheet-metal covering, flashings and drainage before deciding the roof is watertight. Start with safe observations from ground level and from inside the building. Damp marks in the attic, a bent gutter or a displaced component call for the cause to be established. A wet patch does not always mean a hole in the metal — condensation or a blocked outlet may be responsible. Repair should therefore follow diagnosis, and inspection of the roof slope and fixings should be left to a suitably prepared specialist.

Choosing a metal roof for a modern company building depends primarily on how the interior will be used, not on the appearance of the covering alone. An open shelter needs a different approach from a heated warehouse, and a heated warehouse needs a different approach from an office. It is therefore worth checking the temperature and humidity inside and the type of business activity, because the roof must suit conditions on both sides of the building envelope. Define acoustic and fire requirements straight away, together with any equipment planned for the roof, such as ventilation units or photovoltaic installations. A project covering these elements from the outset makes installation easier and allows sensible placement of penetrations, skylights and service routes.