A statutory warranty deed is a form of real property conveyance in some states. It is typically an abbreviated form of a warranty deed, authorized by a statute that allows a deed in the statutory form to include the standard title covenants found in a warranty deed by implication, without the necessity of stating them.
For example, in Washington when a grantor (seller) delivers a statutory warranty deed, the grantor warrants "(1) That at the time of the making and delivery of such deed he was lawfully seized of an indefeasible estate in fee simple, in and to the premises therein described, and had good right and full power to convey the same; (2) that the same were then free from all encumbrances; and (3) that he warrants to the grantee, his heirs and assigns, the quiet and peaceable possession of such premises, and will defend the title thereto against all persons who may lawfully claim the same, and such covenants shall be obligatory upon any grantor, his heirs and personal representatives, as fully and with like effect as if written at full length in such deed." RCW 64.04.030. A warranty deed has nothing to do with the quality or condition of the improvements -- the warranties affect title only.
