overbuild

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To build over or on top of.
• intransitive verb To construct more buildings in (an area) than necessary.
• intransitive verb To build with excessive size or elaboration.
• intransitive verb To construct more homes, office buildings, or commercial complexes than necessary in an area.

from The Century Dictionary.

• To cover, overhang, span, or traverse with a building or structure; build over.
• To build more than the area properly admits of, or than the population requires: as, that part of the town is overbuilt.
• To build beyond the demand; build beyond one's means.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To build over.
• transitive verb To build too much; to build beyond the demand.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb transitive To perform excessive construction on a building or in an area.
• verb transitive To build over or on top of another structure.
• verb transitive To build with excessive size or elaboration.
• verb intransitive To construct more homes, office buildings, or commercial complexes than necessary in an area.