Generally, rooflights formed of translucent sheeting, whether site or factory assembled, are installed in the same manner as fibre cement sheeting. The main difference is that translucent material is thinner and therefore requires more frequent fixing.
Translucent sheet rooflights are laid unmitred, and since the problem of compound layers at end lap situations does not occur, adjacent fibre cement sheets are also left unmitred at these junctions.
Marley Eternit can supply agricultural grade GRP rooflights with a SAB Class 3 fire rating and a Class C impact performance to the ACR[M] 001:2005 test method.
The translucent sheets should be supported at each purlin position by profiled fillers, fibre cement sheets, or fibre cement closure pieces.
End laps and side laps should be sealed with 10mm diameter extruded mastic sealant.
Self sealing fasteners with a synthetic rubber shank or seam bolts and washers with wide bearings are recommended for side stitching. Self tapping screws and blind rivets should not be used for stitching side laps.
Translucent sheets should be fixed through every corrugation (not including the side laps) to the purlins. The same fixings are used as for fibre cement sheeting, but the holes for GRP translucent sheets should be 2mm oversize, and for polycarbonate sheets 6mm oversize (for sheet lengths up to 2m, otherwise 9mm oversize).
All recommendations of the specialist translucent sheeting supplier should be carefully observed. The fixing recommendations will vary depending on the type, grade and supplier of the material being used.