Most manufacturers include guidance in their trade literature on the method of handling and storage of their material on site. All the manufacturers of profiled

5.21 Hard body impact test for steel sheeting.

metal depend upon nominated subcontractors for the detailed design and erection of their cladding. The quality of workmanship on site, particularly at the edge of sheets and the method of fixing, are important factors in the proper assembly of profiled sheeting. Edges of sheets crumpled in handling can look unsightly. The present vogue of using profiled metal horizontally (Fig. 5.12) imposes an even greater requirement for care in the assembly and fixing of flashings and trims.

One of the advantages of profiled sheet metal cladding is that, with care, the fixing subcontractors can adjust the setting out of their sheets to take account of inaccuracies in the structural framing. Fixers prefer to pull on rather than bend sheets to fit an overall dimension, and thus the mean size of the sheets in manufacture is normally below the target size.

Although sheet cladding is subject to very close dimensional control during manufacture, the designer cannot assume that no tolerances are necessary, as spreading of sheets can cause cutting or use of infill pieces on corners and junctions. Fixing contractors need guidance from the designers on where tolerances have been allowed for in the design.

One method of controlling the setting out of profiled sheeting is to use setting-out or spacer jigs mounted on the supporting framework.

The minimum height of stacking profiled sheets on site can be important in reducing the effect of spreading of the overall width of those sheets at the bottom of the stack. Even the way in which the units are lifted on and off the lorry can affect the dimension if they are not crated correctly.

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