What matters is whether the trapezoidal sheet merely encloses the building or also carries loads within the roof structure. In the first case, check above all wind action and the permissible deflection; in the second, check selection for loads in accordance with the design. Profile height alone does not determine suitability; steel grade and thickness, the support scheme and the connections all count. Review the load table for the relevant scheme and conditions, and also consider openings, insulation and surface protection. Leave final design decisions to the designer.

Trapezoidal sheet metal can suit a traditional-style house if its profile, colour and details work with the building form and surroundings. Rather than following a generic recommendation, assess the whole composition: roof proportions, eaves, chimney and façade materials. Check whether the chosen variant disrupts the existing arrangement and whether its technical parameters match the structure and pitch. Compare samples under different lighting conditions and analyse the details at the roof edges. The decision should come from fitting the specific building, not from the name of the covering alone.

T18 trapezoidal steel sheet is suitable for many roofs and façades, but the profile name alone is not enough to place an order. You need to check the cover width, steel thickness and sheet variant. The support spacing depends on the loads and the tables for the specific product. Two sheets marked T18 may have a different width, a different cross-section and different installation conditions. Below we show how to read this data and use it when taking measurements. The number in the name refers to the nominal height of the rib. It does not describe the steel thickness, sheet length or cover width. T18 from two different production lines does not have to have identical ribs.

An anti-condensation layer on the underside of the sheet can reduce dripping of water formed by condensing vapour. It acts as a temporary store of moisture that must subsequently dry out. It is most often considered in adequately ventilated buildings with an uninsulated covering. It does not replace thermal insulation, a vapour barrier or repair of a leaking roof. Whether it makes sense to buy depends on the conditions inside the building and the possibility of removing moisture. The roof surface can cool to a temperature at which the vapour contained in the air begins to condense. Droplets then appear from below, even though no rain has passed through the covering. The phenomenon depends on surface temperature and air humidity. It may be noticeable after a cool night or with a large difference in conditions between the interior and the surroundings.