What is snap seam sheet metal?

Roof coverings with flat longitudinal surfaces attract attention and emphasize the lightness of the building's architecture. The beginnings of roofing with seam sheets dates back decades, when short strips of sheet metal were used and joined by wrapping (on a pipe) or bending (on a seam). Although this method is today considered a craftsmanship and is still used in a large part of public buildings using high-class materials, private houses covered with the rebate method are rarely seen.

That is why a simplified version in the form of a snap seam appeared on the market several years ago, the specification of which built the growing trend of flat roofing. The snap seam is made of standard specification roofing sheet, the cost of the covering service is lower than in the case of the craft seam on the seam.

The main advantages of snap seam sheet metal

In 2011, Bratex Dachy Mrzygłód introduced the first-generation snap seam to its offer, and a few years later, a second-generation product. The year 2017 brought a breakthrough change, as we presented Bratex Snap Lock – indisputably the most refined and aesthetic snap seam. Today, we have three Snap Lock production lines, including one that also produces the modular Bratex Savoy snap seam (we will write a separate article about this unique product).

The seam roofing is characterized by two seams - a covering seam (top seam) and a seam seam (bottom seam), between which there is a flat display surface. For a better effect of the sheathing's attractiveness, the display surface can be profiled in one of several patterns. Profiling is of negligible height and does not change the width of the product.

Variants of finishing the seam surface

Snap Lock seam flat surface finish options

Snap Lock hem is available in three additional surface finishes:

1. "Micro-wave" profiling,
2. "Semi-wave" profiling, which is our original pattern,
3. "Segmentowa" profiling, which is also our original pattern.

For the production of the snap seam, sheet metal in a coil is cut lengthwise to half its standard width. The steel grade is the same as used in the production of trapezoidal sheets and roof tiles. The thickness of the sheet is at least 0,5 mm or 0,6 mm - depending on the selected variant. We recommend 20% thicker sheet metal for this type of flat roofing because it is a stronger material and performs better during handling during installation and throughout its lifetime.

Sheet metal with a thickness of 0,6 mm is available in a variant SSAB Ceramic Matt BT and three colors - graphite (anthracite), black and brown. SSAB's product is protected with 350 grams per square meter of zinc, which is 27% more than standard protection. In addition, the varnish contains components of natural origin, i.e. most nitro solvents have been replaced with biomass of Swedish rapeseed oil. This is a unique solution among all the materials we offer.

Snap Lock hem has an internal zipper. This is a production-demanding type of lock, but it is the best.

Inner zipper in Snap Lock hem

Reasons why Snap Lock is the best:

1. the strongest - after closing, there is no possibility for the sheets to open, e.g. during a storm or hurricane,
2. hides the cut edges - after cutting the sheet, the edges are stripped of varnish, and wrapping them inside (on the rabbet) enhances the aesthetic effect,
3. enables proper execution of transverse laps - connections at roof ledges (windows, chimneys) or with alternating roofing require overlapping the top sheet with the bottom one; thanks to the internal lock, the covering seam of the upper sheet slides over the covering seam of the lower sheet, and the rebate allows the sheets to be held and fitted properly; with the outer zipper (edge ​​folded outward), it is impossible to make an aesthetic transverse overlap, because the upper seam with the same geometry as the lower one will not fit because it cannot be "drawn over the rabbet".

Sheets for the Bratex Snap Lock snap seam have the so-called side bleeds. This is our proprietary design solution. Side bleeds have several advantages:

1. compensate for sheet metal stresses arising when the seams are closed,
2. bring the display surface to the level of the substructure - thanks to this, the flat surface of the sheet rests stably on the membrane or boards,
3. they help calm down, especially during windy days.

Bratex Snap Lock snap hem and side bleeds, marked with a dotted rectangle:

No side bleeds:

The second part of the article is coming soon, and if you have any questions contact us, to get more information about Bratex snap seam sheets and check out our offer!