T35 is worth considering where a simple profile, efficient installation and parameters confirmed by load tables matter. Before measuring, ordering or accepting delivery, check the datasheet for the specific sheet: section geometry, overall and effective cover widths, available thicknesses and steel properties. Also establish whether the variant is intended for a roof or a façade. Two products labelled T35 may differ in their lap design and accessories, so their interchangeability should not be assumed without confirmation in the documentation.

The weight of T18 and T35 trapezoidal sheets follows from the steel thickness, the profile shape and the area the mass is referred to. The coverage area is not the same as the area of the whole sheet. Because T18 and T35 can vary in width, compare their mass in the same unit. With a similar profile, a thicker steel core makes the sheet heavier. Do not rely on the numbers in the profile name alone, as different ribs consume a different strip width per metre of coverage. Catalogue data support transport planning but do not replace roof load-bearing calculations or arrangements for unloading.

It is worth choosing the T14 sheet before building the frame. The profile height alone does not indicate the correct support spacing. First, the application, steel thickness and loads must be determined. Only then can the sheets be ordered. Below we show how to carry out this stage without costly changes on site. The designation T14 refers to a family of low trapezoidal profiles. It is not a full product description. Under this name there may be sheets with different cover widths, thicknesses and profile arrangements. Therefore, an order limited to “T14 in graphite colour” leaves too many unknowns.

The amount next to the profile symbol is only the beginning of the comparison. You need to establish what area it is calculated for and which variant it describes. Sheets with the same trapezoid height may have a different steel thickness or coating. Only after aligning these data can you assess the price per metre of material needed for the roof. Check whether the amount refers to a gross square metre, an effective square metre or a linear metre. Each of these units can lead to a different figure for the same sheet. A price without a specified unit does not allow a reliable comparison of two items.