A roof's wind resistance depends primarily on the continuity of the entire load-transfer system, not on sheet thickness alone. The building owner or user should check whether the design and installation documentation account for the location, height and surroundings of the property, and whether the fixings and edge details match those assumptions. When assessing an existing roof, it is worth looking for signs of earlier alterations, corrosion and loose components. The scope of any inspection is best based on the individual conditions of the building, not on a pattern copied from a neighbouring property.

Before commissioning cleaning or repair, establish whether the corrosion mark comes from the coating, a metal filing or a fixing. An owner can assess critical points from the ground, paying attention to gutters, the chimney, the eaves and places where leaves collect. Also check the condition of the package on delivery and how sheets are stored and cut, because corrosion can begin before installation. The type and parameters of the coatings affect durability, so leave material selection to the designer, and colour alone does not determine how the sheet will behave in a demanding environment.

Start preparing a metal roof by assessing the substrate, not by picking a colour. Identify the existing coating, clear away dirt and locate any corrosion. Only then choose the renovation system and application conditions. Remember that paint will not fix the cause of a leak or strengthen weakened sheet metal. Begin by checking the sheets, fixings and flashings; where the metal is heavily corroded, perforated or permanently deformed, some sections may need replacing. If the roof leaks, first trace the water path and repair the detail.

There is no single sheet thickness suitable for every roof. The same sheet can perform differently with a different support spacing and load. The height and geometry of the profile are also important. When ordering, a distinction must be made between the steel and the protective layers. The choice is based on the data for the specific product and structure, not just on the price of the sheet. Check whether the specification refers to the nominal steel thickness and how the coatings are described. Metallic and organic protections are not the same as the steel core of the sheet. A total measurement with a micrometer does not always correspond to the value that should be used to verify load-bearing capacity.