Final answer:
The minimum height and width for flashing at the intersection of asphalt shingles with a vertical sidewall can vary, but newer recommendations suggest it should be as much as 8 diameters side-to-side and 15 diameters deep.
Step-by-step explanation:
The minimum height and width for flashing at the intersection of asphalt shingles with a vertical sidewall can vary depending on different factors. Previously, the general rule of thumb was to have the flashing extend at least 5 side-to-side and 7-8 deep. However, newer recommendations suggest that the flashing should be as much as 8 diameters side-to-side and 15 diameters deep.