A maintenance bond is a kind of surety bond purchased by the contractor which protects a project owner of a finished construction project for a specified time period (often 1 or 2 years) against faulty materials, workmanship and engineering that could come about after the warranty period expires. A maintenance bond, though not technically insurance, basically functions as an insurance policy on a project and guarantees a contractor will correct any faulty work that arises. A contract, performance, or payment bond will often ‘convert’ to a maintenance bond upon completion of a project. This convertible bond will typically only cover one year after project completion. Sometimes an owner will require 2 years of a maintenance bond in which case an additional cost is commonly charged.