Where ice and water shield is required
Building codes in cold climates require ice and water shield along eaves extending at least 24 inches past the interior wall line. Valleys, skylights, chimneys, plumbing vents, and other penetrations also receive membrane protection. Some jurisdictions require full-deck coverage in certain wind zones.
Rolls are typically 36 inches wide and 75 feet long, covering about 200 square feet after accounting for the two-inch minimum overlap at seams.
Eave coverage = Eave perimeter x Required depth up slope
Required depth is usually 36 inches or enough to extend 24 inches past the interior wall line, whichever is greater.