A design methodology for determining a via enclosure rule for use with a self-aligned double pattern (SADP) technique is disclosed. The shape of the block mask serves as a criterion for choosing a via enclosure rule. Different block mask shapes within an integrated circuit design may utilize different rules and provide different margins for via enclosure. A tight via enclosure design rule reduces the margin of a line beyond the via where possible, while a loose via enclosure design rule increases the margin of a line beyond the via where it is beneficial to do so.