A lease addendum is an added agreement to an existing lease. It is usually agreed upon at the signing of the lease and is a part of the legally binding agreement.
Common items found in a lease addendum include pet clauses, maintenance rules, facility use such as swimming pools and pest control. Not all leases are required to have an addendum, but many do.
It is important for tenants to review the addendum carefully before signing any lease. If there are some things that the tenant would like to see incorporated, it is best to make the inquiry before signing.