When re-covering an existing roof structure a thorough inspection should be undertaken, any deterioration should be rectified and the structure modified as required to accept Onduline sheets. A review of the original roof design should also be made to check that sufficient ventilation and insulation is provided, and if necessary alterations incorporated in the refurbishment.
Note: New build structures must be constructed in accordance with relevant design regulations and requirements
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1 - Setting Out. Purlins must be of sufficient section to give support between the rafters.
Set purlin centres as detailed on the left. Use spacers to keep purlins square. |
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2 - Cutting. First mark out the sheet, then cut with an oiled course toothed hand saw, or preferably a power saw. |
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3 - Sheet Layout. Start fixing sheets at the opposite end of the roof from prevailing winds. Cut a sheet in half
vertically, and use to lay sheet courses in a broken bond pattern |
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4 - Nailing (1). Only use Onduline Safe Top nails on timber; check you have correct side and end sheet laps. Use a
string line to keep fixings in line.
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5 - Nailing (2). Nail sheets every corrugation at the eaves and sheet overlaps, and either side of vertical joints. Nail
every other corrugation on intermediate purlins
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6 - Eaves Detail. The maximum sheet overhang at the eaves is 7cm. Reduce the distance of the first purlin from the
facia accordingly |
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7 - Eaves Tray. Developed for use with the Oversheeting and Ondutile systems. The eaves tray can also be used to
reduce the overhang at the eaves. |
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8 - Eaves Ventilator Strip. Fix to the eaves purlin to stop ingress of birds and large insects, whilst allowing free airflow
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9 - Corrugation Filler. Seals corrugations at eaves and ridge from penetration of sand and dust into the roof space.
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10 - Ridge Unit Fixing (1). Fit ridge board and support purlin. Fix second purlin, its position being dictated by the roof pitch.
The sheet/ridge can then be fixed.
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11 - Ridge Unit Fixing (2). Start fixing the ridge at the opposite end of the roof from prevailing winds and form a 12.5cm
overlap. Use a string line to align and nail at every corrugation
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