Bratex trapezoidal sheets, a classic on the roof

Trapezoid-shaped sheet metal is a popular roofing material from the group of the simplest profiles. Production consists in introducing the sheet metal in a circle to the profiling line, forming it longitudinally and cutting it to the desired size. The formation of the trapezoidal sheet starts from the center. First, a wave is formed with a height lower than the target one. With each subsequent pair of forming stations (shafts with rings), the wave profile is deepened (higher) and the overall width of the sheet decreases. Then the formation of the next extreme trapezoids begins and the process is repeated until the final profile is obtained at the end of the machine.

Types of trapezoidal sheets for individual construction and commercial buildings

18mm trapezoid

Trapeze T18

The most common trapezoid for the roofs of houses is a profile with a height of 18 millimeters. T18 trapezoidal sheets by Bratex have seven full trapezoids. It is worth paying attention to this when choosing, because the number of trapezoidal profiles affects the strength (load capacity) of the sheet.

14mm trapezoid

Trapeze T14

An equally popular profile is characterized by a denser arrangement of trapezoids, of which there are as many as nine, each with a height of 14 mm. The product is perfect for smaller areas.

35mm trapezoid

Trapeze T35

Strong appearance, solid trapezoid with a height of 3,5 cm and five waves, less often chosen for individual construction, more often intended for covering smaller warehouses. Please note that the high trapezoidal wave is noticeable when cut at valley gutters. That's why not often this product is the choice for homes.

8mm trapezoid

Trapeze T8

The purpose of the product is most often the headlining, also door or wall padding. The trapezoid with a height of 8 millimeters works well as an ordinary soffit, however, it should be remembered that the screws remain visible, and during the assembly the contractor has to deal with 120 cm wide sheets, which does not facilitate assembly.

As an alternative to the soffit, the company's offer includes panels P01 without a joint and P02 with a joint, these are products of extraordinary aesthetics. They have a hidden fastening, a dedicated set of flashings and a perforated mounting strip, which is also a ventilation system in the P02 model (basically unnecessary with a metal headliner). We encourage you to download a dedicated one panels catalogue.

Bratex soffit panels

Facade version

T14, T18 and T35 trapezoids can be ordered in the façade version, i.e. with varnish on the bottom. The waves are then slightly offset from the side edge of the sheet so as to obtain a precise overlap. The purpose of the façade versions is to cover the wall of the building. It should be noted that the screws on the facade remain visible and that is why Bratex's offer is now being enriched with facade panels. These are products with a hidden mounting strip, closed on the sides, in many stylistic variants, with a set of dedicated flashings. We encourage you to familiarize yourself with a separate catalog when it becomes available.

Trapezoidal facade T14

Trapezoidal facade T18

Trapezoidal facade T35

fleece

Trapezoidal sheets in the roof version can be delivered with DRIPSTOP anti-condensation fleece. The interlining with a weight of 95 g/sqm applied to the sheet is a proposal for thermally non-insulated roof partitions, where the phenomenon of water vapor condensation is a problem. Under normal conditions, condensed water on the underside of the sheet (where the dew point occurs) runs down the sheet and drips onto the livestock. The solution to this problem is the DRIPSTOP interlining, which absorbs the resulting moisture and holds it from the time of drying. When using this product, it is necessary to ensure perfect ventilation in the eaves-ridge line so that the natural air flow dries the wet interlining. More details can be found in the Product Documentation.

Length

We produce trapezoidal sheets up to 8 meters long, and 18 and 35 mm profiles up to 12 meters long. We produce products in the aluminum variant only up to 6 meters, due to twice the linear thermal expansion between winter and summer.

Fireflies

The Bratex offer also includes roof skylights for T35 and T18 trapezoidal sheets. Bratex skylights are dedicated to our profiles, so the longitudinal and transverse joint is as accurate as if another sheet of trapezoidal sheet was installed. Skylights are a good choice for carports and uninsulated buildings, where there is a need to illuminate the place. They are not thermally insulated. The skylights are made of high-quality material, i.e. polycarbonate, thanks to which they are 90% transparent. They have high strength parameters, resistance to UV and weather conditions. They are 1 mm thick and have a fixed length of 2,4 m. Skylights cannot be walked on so as not to damage them.

Assembly

In accordance with the assumptions of the standard and the declaration of performance issued by the manufacturer Bratex Dachy Mrzygłód, the spacing of installation battens under trapezoidal sheets should not exceed 40 cm. In fact, customers lay easy every 50 cm and this also works.
Laying trapezoidal sheets is simple, requires overlapping (i.e. along the length) and alignment at the eaves line. Flashings of roof penetrations (chimneys, windows) should be made in accordance with the roofing art, because these are the most sensitive places where incorrectly performed flashing will be the place of leakage.

Cross-joining

Trapezoidal sheets are most often ordered to the length of the rafters and this is the correct approach. For roofs requiring longer sheets, the sheets should be joined transversely by placing the top top sheet on top of the bottom one. Unfortunately, this type of product is not designed to compensate for excess sheet thickness. Similarly with the place where four sheets of metal are joined. It should be taken into account that the places of joining may be noticeable and it should be taken into account that at the joints of trapezoidal sheets, rainwater with impurities is sucked in between the sheets. This is a feature of the production of trapezoidal sheet and in extreme cases may lead to degradation of the product. More about this phenomenon and solving this problem by our company is described in the article for Bratex system metal roof tiles. When connecting sheets with interlining, it should be peeled off along the length of the overlap and peeled off along the length of the ridge flashing. Unglued interlining will absorb water and over time will lead to the degradation of the metal sheet.

Ventilation

As with any type of roofing, also in the case of trapezoidal sheets, the issue of sheathing ventilation, i.e. air flow between the sheet and the membrane, should be taken into account. It is absolutely forbidden to use foam seals at the eaves and at the ridge. Such seals prevent the passage of air and the drying of the condensed water membrane on the underside of the sheets. Combs or vent strips are used at the eave line to prevent martens and birds from entering through these openings. On the ridge under the flashing, a ventilation tape with a technical fabric is used to ensure air flow.