County Laws & Code

Complete County Code:

The complete county code is maintained by Municipal Code Corporation, the nation's leading codifier.  This online document is updated semi-annually.  However, in order to keep pace with changes to Chapter 40 of the County Code, known as the Unified Development Code (UDC), an up-to-date copy of this chapter is made available below.  Other selected sections of the County Code related to the UDC and Building Code are also available in PDF format further below.

Unified Development Code:

Chapter 40 of the county Code is the primary guide to development within New Castle County. The Unified Development Code (UDC) establishes standards, procedures, and minimum requirements, consistent with the Comprehensive Development Plan.  The UDC regulates and controls the following: creation and administration of zoning districts; general development of real estate in the unincorporated areas of New Castle County; planning and subdivision of lands; and use, bulk, design and location of land and buildings.

Cover Page from New UDC (Updated) Print Opens in new window

*Note: the online version of the UDC is temporarily unavailable. In the meantime, please utilize the PDF version. 

A PDF version of the complete UDC is available at: Unified Development Code (Revised 5/29/19 plus Appendix 2 fee changes effective 7/1/19)).  

Two additional UDC documents are also available below:

Please also see our UDC Revisions page for information regarding any updates being considered for the UDC.

Property Maintenance Code: 

The New Castle County Property Maintenance Code applies to premises and structures and contains minimum standards for light, ventilation, space, heating, sanitation, protection from the elements, a reasonable level of safety from fire and other hazards, and sanitary maintenance.

County Code Enforcement applies the International Property Maintenance Code, 2018 edition as amended by local amendments.

Chapter 7 of the New Castle County Code (PDF) and the Appendix (PDF) contain those amendments and are available for download. Copies of the ICC Codes may be purchased directly from the International Code Council (ICC) at

Building Code:

The Department of Land Use regulates construction to the standards of the following:

  • International Building Code, 2018 edition
  • International Residential Code, 2018 edition
  • International Existing Building Code, 2018 edition
  • International Swimming Pool and Spa Code, 2018 edition
  • International Energy Conservation Code 2012
  • International Mechanical Code, 2015 edition
  • International Fuel Gas Code, 2015 edition
  • International Plumbing Code, 2015 edition

Chapter 6 (PDF) of the New Castle County Code and its appendices (PDF) contain amendments to the adopted codes and is available for download. Copies of the ICC Codes may be purchased from the Department of Land Use. In addition, a list of International Code Council and Staff Code Interpretations may be found online at the Code Opinions by Code Version and Section