As a landlord, do I have any responsibility for renters belongings left behind when lease is ended (agreed to in writing by both parties).

Kathleen- A tenant has possession of the property until they move out, voluntarily or involuntarily by eviction. Even though the lease term ends you have no right to possession until the tenant moves out. If the tenant remains in possession on March 16, your only option is eviction by court process. You may not enter , change the lock nor remove tenants possession without court order. If the tenant abandons the property for 14 days you may enter the property inventory the possessions and store them. You must publish a notice of intended disposal and mail the notice to tenants last known address. You can the sell give away or throw away the possessions. There are time frames for notice and disposal. If the tenant is evicted by court process and leaves possessions behind you publish the same notice and dispose of the possessions. All of this may delay your construction. Without publishing the notice ans waiting out the time you cannot destroy the tenants possessions.