Impervious Area or Built-Upon Area

What does impervious area refer to?

Why do we have impervious restrictions? 

  • State and local regulations (specifically water supply watershed protection ordinances and postconstruction ordinances) protect streams and lakes in Mecklenburg County from pollution by restricting activities in the land areas that drain to them. Built-upon area (also called impervious area) is a source of pollution that is controlled by these regulations. Pollutants, such as oil and chemicals, deposited on these surfaces wash straight to creeks and lakes in runoff during rain events causing negative water quality impacts.  

What materials are considered impervious?

  • Built-upon area is defined as both impervious and partially impervious cover including buildings, pavement, gravel, recreational facilities (tennis courts, etc.) but does not include wooden slatted decks and the water area of a swimming pool.

Do all properties have impervious restrictions? 

  • Built-upon area restrictions apply to all properties located in water supply watershed restriction areas and most all other properties in Mecklenburg County. Properties developed in Huntersville after July 1, 2007, are likely subject to built-upon area restrictions. Click HERE to view a map of the area impacted by impervious restrictions.

How do I determine if my property has impervious restrictions? 

  • To determine if a property is located in a water supply watershed restriction area, go to (select “Departments”, select “Geospatial Information Services”, select “POLARIS 3G”). Enter the property address or PID in the search field (upper left corner) and select “Floodplain, Zoning & Watershed Info” at the lower-left portion of the screen. If a “Watershed Class” such as PA or Ca is indicated under the heading “Watershed District” at the bottom left portion of the screen, then the property is located in a water supply watershed restriction area and is likely subject to the built-upon area requirements. To view the specific watershed ordinances and guidelines, click on “Detailed Information” at the bottom left portion of the screen
  • If a property is located in a subdivision, the maximum built upon area allocated to that property can be obtained from the approved recorded plat, which is sometimes available by using the “Legal Desc.” link on the left side of the screen in POLARIS under the property address. This will take you to the Register of Deeds website for viewing of the recorded plat. While viewing the recorded plat you will see on the left-hand side of the page a “Related Documents” link. Click this link to see if there is a revised plat that may include changes to allotted impervious restrictions. The revised plat will be noted as MAP/R. Should you want to go back to the previous plat click the back button. If the property in question is not located in a subdivision or if the subdivision was approved prior to the effective date of the regulation, then the maximum allowed built upon area can be obtained by reviewing the applicable regulation as described above.
  • If you need assistance determining the impervious restrictions you can email the property address to and request assistance with impervious calculations. One of our Planners will be happy to assist you. 

Are there types of structures/surfaces that I could use that would not be considered impervious?

  • Slatted wood decks and walkways (such as a handicap ramp) do not count as impervious surfaces. If, however, a deck is enclosed to create a screened porch or sunroom, the roof means it now becomes impervious and must be counted towards any maximum allowance.
  • NOTE: Products marketed as permeable pavers have not been approved by Mecklenburg County for use as permeable. These items will count as impervious surface. 

Show All Answers

1. Accessory Dwelling/Mother-In-Law Suites
2. Building Codes
3. Building Permits
4. Business License
5. Commercial Projects
6. Decks
7. Fences
8. Home Based Businesses
9. Impervious Area or Built-Upon Area
10. Livestock (Chickens, Goats, Horses, etc.)
11. Nuisance/Violations/Mimimum HousingCode
12. Plat/Survey/Floorplan
13. Setbacks
14. Swimming Pools
15. Water/Sewer/Septic
16. Zoning