English to Italian Tech/Engineering Construction / Civil Engineering roofs

Taken from a fire resistance test report written by a non native speaker:
"2.2.3 Fixing of the panels
Panels are through-fixed to the support construction by means of:
- steel self-drilling screws 5.5 x 270;
- each panel is through-fixed from the unexposed side to each edge support beam at each trapeze rib;
the panels are through-fixed between each other from the unexposed side at the joints between the panels.
U shaped steel storm washers are placed under steel self-drilling screws.
2.2.4 Joint fixing
No joint-stitching screws are used for additional joint fixing."
No further context is available.