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. 

Click here to access the online version of the UDC.

Two additional UDC documents are also available below:

• UDC Appendix 3 - Plant Lists
• UDC Bufferyard Model

Please also see our Legislation and Initiatives page for information regarding any updates being considered for the UDC.

Drainage Code: 

Ordinance 22-030, that will reduce water pollution and flooding in New Castle County, was signed into law on April 23, 2022. The ordinance updates the County’s Drainage Code, requiring developers to strategically introduce quality treatment practices to their stormwater runoff and reduce the impacts of flooding attributable to legacy development through better stormwater facilities. This is important in this era of climate change where we have more frequent and more intense storm events. Improvements to our stormwater requirements are also important given recent reporting on the poor quality of the State’s rivers and streams. View an unofficial copy of the Drainage Code.

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. Please visit our Code Enforcement page for more information.

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 2018 – effective 1/1/21
• International Mechanical Code, 2018 edition – effective 1/1/21
• International Fuel Gas Code, 2018 edition – effective 1/1/21
• International Plumbing Code, 2018 edition – effective 1/1/21
  

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 listed above may be purchased directly from the International Code Council. 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