Floodplain Development Information

                                   FLOODPLAIN DEVELOPMENT



If your home or business is located within the floodway fringe or floodway as designated on the adopted February 4, 2015, Flood Insurance Maps (FIRM’s), you will want to be aware of the “50% rule”.  For help in understanding how the City applies this rule, please contact the University City Department of Public Works at 314-505-8560.

Essentially, structures located in these flood-prone areas which are “substantially damaged” or “substantially improved” must be brought into compliance with the City’s floodplain development regulations, which may include elevating the lowest floor of the structure at least 2.0 foot above the base flood elevation.

 Substantial Damage

When the cost to repair any damaged structure to its previous condition would equal or exceed 50% of the market value of the structure before the damage occurred.

 Substantial Improvement

When the cost of any reconstruction, rehabilitation, addition, or other improvement of a structure would equal or exceed 50% of the market value of the structure before “start of construction”. This term includes structures which have incurred “substantial damage” regardless of the actual repair work performed. The term does not, however, include either:

  • Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications that have been identified by the city code enforcement official and which are the minimum necessary to assure safe living conditions.
  • Any alteration of a “historic structure”, provided that the alteration will not preclude the structure’s continued designation as a “historic structure”.
  • An improvement that does not require a building permit under applicable codes.

 Identifying Classification

 University City, following the National Flood Insurance Program (NFIP) requirements, has the responsibility to determine “substantial damage” and “substantial improvement” and has implemented the following procedures to do so:  University City will calculate Market Value by using the St. Louis County tax assessment value of your structure (excluding land). If you disagree with this estimate of Market Value, you may hire a state licensed appraiser and submit a comparable property appraisal for the market value of the structure

  1. You must submit a Floodplain Development Permit Application.
  • Identify and describe the work to be covered by the floodplain development permit.
  • Describe the land on which the proposed work is to be done by lot, block and tract, house and street address, or similar description that will readily identify and specifically locate the proposed structure or work.
  • Indicate the use or occupancy for which the proposed work is intended.
  • Indicated the assessed value of the structure and the fair market value of the improvement.
  • Specify whether development is located in a designated floodway fringe or floodway.
  • You must obtain and submit to University City a detailed and complete cost estimate for the addition, remodeling, reconstruction, or repair of all the damages sustained by your home or business, prepared and signed by a licensed general contractor. University City will evaluate the costs of improvements or repairs and determine if they are fair and reasonable.
  1. If your home is determined to have “substantial damage” or is proposed to be “substantially improved”, then an elevation certificate must be submitted to determine the lowest floor elevation.
  • If the lowest floor is below the base flood elevation, then the structure must be elevated at least 1.0 foot above the base flood elevation. Likewise, all utility and sanitary facilities must be elevated or floodproofed up to the regulatory flood protection elevation. Single electric service for recreational uses must be elevated a minimum of 10 feet above existing average grade.
  • Building plans must be prepared and submitted that show how the structure is to be elevated. One set of your sealed plans must be submitted to the University City Planning Department. An elevation certificate must be submitted to the University City Public Works Department and have the seal of an engineer or land surveyor.
  1. If your business is determined to have “substantial damage” or is proposed to be “substantially improved”, then a certificate from a registered professional engineer or architect that the floodproofed structure meets the floodproofing criteria.


  1. Other information that may be requested by the Floodplain Administrator may include:
  • Description of the extent to which any watercourse will be altered or relocated as a result of proposed development.
  • In order to make any change to a floodway, a State of Missouri professional engineer must perform a hydrological study. The study must be formulated indicating no change of elevation or direction of flow of water will occur at, below or above the improvement because of the improvement.
  • A “No-Rise Certificate” is required when any work is performed or proposed in a regulatory floodway.
  • A U.S. Army Corps of Engineers 404 Permit.
  • State Department of Natural resources 401 Permit.
  • Environmental Protection Agency NPDES Permit.