Is a Shelf Part of the Real Estate?
As a lone item, a piece of glass is personal property as opposed to real property, but it may be considered part of a fixture. The relationship of landlord and tenant is created by contract, and the terms of the contract (lease) generally determine the rights of the landlord and tenant. You should carefully review the terms of the lease agreement including any definitions of alterations, improvements and trade fixtures to determine your rights and your landlord's obligations regarding the glass. If you are referring to a glass shelf whose removal would limit the functionality of the cabinet, it would depend on the circumstances, such as whether it was removed for repair and who has duty of repair in the situation.
Generally, improvements made by a tenant that are permanently attached to the property become part of the real estate. A trade fixture is an improvement that is attached to real estate that is unique to the operation of a business. It may be removable by a tenant if it can be done without damaging the property. A trade fixture is installed by a tenant under the terms of a lease and is used in the business of the tenant. Trade fixtures are removable by the tenant before the lease expires, however, the tenant is liable for any damages caused by such removal. They are distinguished from other fixtures which are considered improvements to real property and which must be left intact when the tenant vacates the premises.
In the U.S., a sale of land generally includes any permanent fixtures, unless an item is expressly excluded. Trade fixtures are an exception to this general rule. Common factors examined in determining the nature of the fixture include the degree of the item’s annexation or permanence to the property—whether it can be removed without material injury to the land or building to which it was attached; the extent to which the item was adapted for the intended use of the property, that is, its appropriateness for the purposes for which the property was used; and the intention of the person who annexed it.