68 Pa. Stat. § 101
In all cases in which any real estate is now or shall be hereafter held by two or more persons as tenants in common, and one or more of said tenants shall have been or shall hereafter be in possession of said real estate, it shall be lawful for any one or more of said tenants in common, not in possession, to sue for and recover from such tenants in possession his or their proportionate part of the rental value of said real estate for the time such real estate shall have been in possession as aforesaid; and in case of partition of such real estate held in common as aforesaid, the parties in possession shall have deducted from their distributive shares of said real estate the rental value thereof to which their co-tenant or tenants are entitled.
68 P.S. § 101