What affects the price of T18 and T35 trapezoidal steel sheets?

The designation T18 or T35 alone does not describe the whole product. Sheets may differ in width, steel grade, thickness and coating. The unit used in the offer may also differ. A cheaper entry does not always mean cheaper covering of the same roof slope.

Before comparing, record the parameters of both proposals in a single table. You need the nominal sheet thickness, the type of surface protection and the usable width. Check the length of the sheets and the number of pieces. Only such data allows you to assess the actual quantity of material being purchased and the extent of the price difference.

Catalogue example, edition of 28 October 2026: roof sheet T18 with a thickness of 0.50 mm in 25 µm polyester costs €10.34 gross per m² usable. For the T35 version with the same thickness and type of coating, €11.31 gross per m² usable is stated. These are prices for specific variants, not the entire market.

For 100 m² of covering, this gives €1034.00 and €1131.00 respectively, before taking cutting to size into account. The difference is €97.00. This calculation does not determine which profile suits the roof. The choice must first meet the requirements for load-bearing capacity, supports and slope. The cheaper variant will not replace a properly selected solution.

In the same example, T18 has an overall width of 1142 mm and a usable width of 1100 mm. The gross price per overall metre is €9.96. After allowing for the width ratio, we obtain approximately €10.34 per metre of coverage. The difference results from the part of the sheet concealed in the overlap.

With other profiles the ratio will be different. In addition, longitudinal joints between sheets and cut-offs reduce the area that remains usable. The most reliable comparison is based on a complete schedule of sheets. Do not mix the net price of one material with the gross price of another, and do not compare different units.

Greater sheet thickness means more steel and usually a higher price. It may also change the load-bearing parameters of the profile. However, it does not justify arbitrarily increasing the support spacing. The result must be read from the relevant load table, taking the entire installation system into account.

The type of coating affects the cost and the operational requirements. For the example T35 0.50 mm, the price list of 28 October 2026 states €9.20 net per m² usable in 25 µm polyester. The version with 35 µm matt polyester has a price of €10.40 net. This is a comparison of two specified variants, not proof that every matt is better than gloss.

In some applications, an anti-condensation fleece under the sheet is considered. Its purpose is to retain a limited amount of condensate and allow subsequent drying out. The solution requires adequate ventilation. Without it, even a well-executed layer may not meet expectations.

It should not be bought as a substitute for insulation or complete protection against water vapour in a house. Before paying the supplement, establish the building’s purpose and the humidity conditions. Calculate the cost of the solution separately for an unheated building and separately for rooms used all year round. The range of layers required may be completely different.

The price of the covering is increased by flashings, fasteners and seals intended for the selected system. The substructure, drainage and ventilation elements also matter. On a roof with chimneys and roof valleys, the share of these items increases. Omitting them gives an underestimated quote, even when the price of the sheet is correct.

Check the cost of transport and unloading of long sheets. Establish whether the contractor’s quote includes preparation of the substrate and disposal of waste. For a renovation, add removal of the old covering and any necessary repairs. The price per metre of material answers only a small part of the questions about the budget for the whole job.

Provide the roof plan, the lengths of the roof slopes, the pitch and the locations of service penetrations. Specify the required profile, thickness, colour and type of coating. If the selection has not yet been finalised, ask for variants consistent with the design. Do not replace T35 with T18 on your own merely to reduce the total.

In the finished offer, check the validity period and the scope of delivery. The catalogue price list is a reference point, not a commitment by the seller. The sheet layout and the complete set of accessories will allow the roof to be calculated much more accurately than a broad price range. This is the data worth keeping for comparing subsequent proposals.