CUSTOMER REQUEST:
We are often asked why, when we are asked to size a fixing system on roofs in grecata lamiera, flat or curved (cupolini), we require so many technical details such as the material, the thickness of the sheet metal, the wheelbase between the Greeks and the slope of the roof.
OUR EXPLANATION:
This is because we need to verify that the loads of wind and snow, calculated according to the Technical Construction Standard (NTC2018), which insist on the system, are lower than the design loads of the fixing elements, with particular attention to the profiles and fixings to the sheet metal (with screws or rivets).
In particular:
- I profiles, or the profile clips, they come tested under traction (wind load) and compression (snow load), modeling them as supported/supported beams (see Figure 1). The pitch of the Greek frets therefore constitutes the distance “L” between the supports of the “beam”.
- Il study material and sheet metal thickness These are fundamental parameters for verifying the correct sizing of the sheet metal fastenings, both in number and type. TEKNOMEGA offers the possibility of using both rivets and self-drilling screws; the resisting behavior of these two elements, however, is different, with rivets generally offering superior shear resistance.
Let us consider, for example, exampleA system in Cremona on a 9-meter-high roof made of corrugated sheet metal with a 10° slope is to be constructed with 2094 x 1134 panels, arranged vertically and fixed along the long side. Assuming the corrugated sheet metal is 5/10 mm thick steel and has a 250 mm corrugation spacing, we see that the profile and section solutions are all valid.
As regards the fixings, we see that, if we want to use one low profile piece (See Figure 2), care must be taken when choosing between screws and rivets because, with 2 fixing points, only the riveted solution is suitable.
Figure 2
Conclusion: even for sheet metal roofs, TEKNOMEGA carries out all the necessary checks to guarantee a robust and certifiable solution.
