Roof pitch for trapezoidal sheet - that's how tall it should be

With the roofing of a roof with trapezoidal sheet, the tightness of the roof should be ensured. Ensuring that rainwater drains quickly from the roof by keeping the roof pitch large enough prevents moisture penetration.

Plan overlap of the sheets

In order to ensure the tightness of the roof with a covering made of trapezoidal sheets, not only the roof pitch must be sufficiently high, but the sheets must also overlap a bit depending on the inclination angle of the roof.

Overlap transverse joints

The tightness is guaranteed by most manufacturers only when certain roof pitches are performed with a certain length of overlap at the transverse joints.

But if the roof inclination is less than ten degrees, a polyethylene foam sealing tape is generally recommended to cover the roof with waterproof joints.

  • Roof pitch up to 3 degrees - no crossbar possible
  • Roof pitch 3 to 5 degrees - 20 centimeters overlap
  • Roof pitch 5 to 20 degrees - 15 centimeters overlap
  • Roof pitch from 20 degrees - 10 centimeters overlap

Seal the longitudinal joint

If the roof pitch is below ten degrees, a polyethylene foam sealing tape should be applied over the entire seam. In any case, the overlap must always be a trapezoid field in the longitudinal direction.

Avoid damp support beams

Trapezoidal sheets sweat now, no matter whether they have a sufficiently large roof pitch or not. Thus, if the trapezoidal sheets have not been insulated, some moisture may come underneath the sheets.

Of course, the wood of the girders does not like this permanent moisture permanently. Therefore, you should slide between the support beams and the trapezoidal sheet a piece of tar paper. This keeps the wood protected and lasts much longer.

Tips & Tricks

The water must be able to flow freely from the roof. So are dirt or mosses, which settle in the trapezoidal grooves, a risk for a rainproof roof and for the longevity of the roofing.

For this reason, a gradient is important, which is chosen large enough. This activates a certain self-cleaning of the roof, because dirt is washed away immediately in the next rain, without you have to lend a hand on the roof for a long time.

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