01
Set exposure correctly
Determine headlap first, then apply the field exposure formula. A change of one-half inch in exposure materially changes course count on a long slope.
02
Protect side-joint relationships
Narrow widths require careful bond control around valleys and penetrations. Avoid slivers by adjusting several pieces before the obstruction.
03
Estimate beyond the field
Include under-eave pieces, top courses, diagonal cuts, hips, valleys, dormers and attic stock. Historic matching may require extra sorting for thickness and color.