Pennsylvania Statutes Title 68 P.S. Real and Personal Property § 250.202. Leases for more than three years

Real property, including any personal property thereon, may be leased for a term of more than three years by a landlord to a tenant or by their respective agents lawfully authorized in writing. Any such lease must be in writing and signed by the parties making or creating the same, otherwise it shall have the force and effect of a lease at will only and shall not be given any greater force or effect either in law or equity, notwithstanding any consideration therefor, unless the tenancy has continued for more than one year and the landlord and tenant have recognized its rightful existence by claiming and admitting liability for the rent, in which case the tenancy shall become one from year to year.