In general, buyers of real property should assume that all statements and indications regarding square footage, lot size, boundary lines, and encroachments are approximations. Before entering into a sale agreement, a buyer should employ a qualified appraiser or land surveyor to determine the exact square footage, lot size and boundaries. San Francisco housing is expensive and a new home buyer should not realize "after the fact" that their property is really 400 square feet less than what they thought or that their building actually extends two feet onto the neighbors property. These types of problems can be costly to resolve and may significantly alter an owners ability to sell the property in the future. Title insurance policies often have clauses stating that the policy will not cover discrepancies in boundary lines.