As the preference for nonsmoking rental properties grows alongside increased government regulations, landlords who wish to initiate a smoking ban have to develop a plan of action. In order create an addendum, your original lease needs to not prohibit the action and the addendum needs to meet all basic contract requirements. After you write your addendum, you will need to execute it and include it with your original lease. Whether you are a landlord or tenant, there may be times when your residential or commercial lease needs to be added to. In these circumstances, you will use a lease addendum to make the required changes. Unlike a lease amendment, which is a change in the contract itself, a lease addendum is an additional document that is added to the existing lease agreement. For example, in the residential lease context, pet ownership, roommate expectations, crime free agreements, and lawn care policies may all be controlled by addenda (if they are not already controlled by the lease itself).