COP v3.0:installation; setting-out

14.8 Setting Out  

Underlay support if required must be installed before laying of roof sheets commences, and underlay may be cut to length before use.

Laying should commence considering building sequence, prevailing weather, and architectural details. It is not necessary to face laps away from prevailing wind direction as roofs must be designed to withstand weather from any quarter. On critical jobs or when using curved sheets, it is advisable that side laps face away from the line of sight.

Sheets should be laid square to the nearest architectural feature, and regularly checked to correct any misalignment of sheet or squareness of structure. Laying out of square will result in saw-toothing of the eaves line. Saw-toothing of greater than 5 mm may be trimmed back to form a straight line.