Impervious surface area is regulated by Wake County. The County has prepared a presentation, Residential Lot Impervious Surface Area, to help property owners understand impervious surfaces, impervious surface area limits and the stormwater deviation process.
Single Lots
Stormwater Certifications
Review Fee = $50
Each zoning district has a maximum impervious surface percentage that is allowed. The upper limit on residential lots is 30% impervious; however, subdivisions may range from 6% to 30% impervious depending on the level of stormwater treatment installed during development. During the subdivision approval process, the application and their design engineer determined what level of impervious the subdivision would have and whether stormwater devices would be installed for the entire subdivision.
Post-2006 subdivisions are recorded with a perpetuity statement, "Maximum Impervious Area Square Footage on each Individual Lot will be Stringently Enforced with no Exceptions into Perpetuity." Lots in these subdivisions are not permitted to deviate from the approved impervious on an individual lot basis. If there is no perpetuity statement, individual lot stormwater management may be permitted by application and installation of stormwater treatment. The application will be referred to stormwater staff for review and you will be invoiced $50 through the Portal.
Building permit applications are required to supply a plot plan which includes a scale drawing of the lot and the proposed impervious features (house footprint, driveway, sidewalks, porches, outbuildings, etc.).
Stormwater staff will contact the applicant to allow for revision of the plan or for potential deviation from the impervious requirement.
Stormwater Deviation Process
Permit Fee = $400
For recently recorded lots, the recorded plats should list the maximum allowable impervious area per lot. For older subdivisions, you will have to determine your zoning district. When searching for your property's zoning district, iMaps can be a helpful tool to determine this criteria. Simply locate your property by searching by owner, an address, or PIN number. Contact the Planning Department for Zoning questions.
Stormwater Control Measures may be installed when a residential site plan is allowed to exceed the maximum allowable impervious surface coverage on that lot. Small deviations can be mitigated by the applicant or homeowner; however, large Stormwater Management devices should be designed by qualified professionals. A few solutions are listed below; however, keep in mind that there are many different possibilities for stormwater management.
Refer to the NC DWR Stormwater Design Manual for detailed explanation. However, engineering design is not required for most systems. Permeable pavement is the exception, compliance with the State manual is required.
- Rain Gardens
- Cistern (above ground or underground tanks)
- Rain Barrels
- Infiltration Devices
- Dry detention basins
- Permeable Pavement - requires engineered design
Deviation requirements include:
- Deviation Application and site plan
- Stormwater Deviation Submittal Checklist
- Permit fee ($400)
- Approved stormwater management plan
- As-built survey
- Recorded maintenance document
- Recorded stormwater agreement
- Homeowners Annual Inspection Checklist
To schedule a pre-submittal meeting please contact Watershed Management at 919-856-7436. For additional guidance please review section 4.3.2 of the Stormwater Design Manual.
Apply for Stormwater Deviation through the Permit Portal; also upload a site plan with the stormwater device(s) to your building permit or land use plan; septic review may be required.
Technical support in design of rain gardens and cisterns is available through NC Cooperative Extension.
Falls Lake Single Lot Stormwater Requirements
If you are building a new home in the Falls Lake Watershed with over 1/2 acre of residential land disturbance and non-residential with over 12,000 sq. ft., you may need to apply for a Stormwater Permit to comply with the Falls Lake Stormwater Rules.
These rules apply to lots that are rural, i.e. outside a permitted subdivision, in an minor subdivision or existing subdivision without recorded impervious limits.
Apply through the Permit Portal for:
- Permits
- Watershed
- Stormwater Management – Residential
Subdivisions
Wake County Subdivisions
Subdivision approval in Wake County is a tiered process that starts with the Planning Department. Environmental Services/Watershed Management staff reviews preliminary and construction plans for compliance with stormwater, erosion control and floodplain management. Environmental Services / On Site Wastewater reviews proposed subdivisions for well and septic capacity.
- Preliminary Approval – Apply through the Permit Portal / PLANS for Preliminary Subdivision PLAN – a PLG case will be created.
- Construction Plan Approval – Apply through the Permit Portal / PLANS for Construction PLAN – a PLG case will be created.
Upload construction plans with erosion control and stormwater details, narrative, calculations, stormwater tool, etc; stormwater (SWF) and land disturbance (SEC) permits will be created and linked to the PLG case; if flood review is needed, you will be directed to apply for a Flood Study Permit. - Final Plat Approval – Apply through the Permit Portal for Plat Approval; a Performance Guarantee may be required if stormwater improvements have not been completed.
Municipal Subdivisions
Requirements are specific to each municipal area
Please contact the appropriate municipal area for application requirements.
Wake County issues land disturbance permits for Garner, Morrisville, Rolesville, Wendell and Zebulon. You must have Plan Approval from the appropriate local government prior to Wake County land disturbance permit approval.
Wake County issues stormwater permits for Rolesville, Wendell and Zebulon. You must have Plan Approval from the appropriate local government prior to Wake County stormwater permit approval. Apply for the Wake County Stormwater Permit through the Permit Portal.
Garner and Morrisville are responsible for final approval and closeout of stormwater in their jurisdictions. For projects in Rolesville, Wendell and Zebulon: Completion of stormwater conditions of approval (as-built survey, engineer's certificate, field inspection compliance, recorded documents, etc.) are required prior to release of performance guarantee and permit closeout.
Non-Residential Development
Wake County Projects
Commercial Building Permit and Stormwater Construction Approval Needed
Non-residential permit approval in Wake County starts with the Planning Department; contact Planning Staff to schedule a pre-submittal meeting. Non-residential projects include townhomes, apartments, churches, athletic fields and other commercial developments.
Questions we may answer include: Is the proposed use allowable? Is a rezoning needed? Is a special use permit required? Can you proceed with application for construction plan review? What are the submittal requirements?
Watershed Management staff reviews building permits and construction plans for compliance with stormwater, erosion control and floodplain management. Onsite Water Protection reviews proposed development for well and septic capacity.
- Construction Plan Approval – Apply through the Permit Portal for Construction Plan Review, SEC and SWF permits as needed. If there are State or Federal funds involved, erosion control will be issued by the State.
- Commercial Building Permit – Apply through the Permit Portal for Commercial Building Permit; a hold will be placed on permit issuance until erosion control measures have been installed and approved.
- Exempt Plat Approval (record approved impervious limits and stormwater SCMs and associated easements) – Apply through the Permit Portal for Plat Approval
- Stormwater requirements – As-built survey and field inspections, recordation of easements and stormwater agreement shall be completed prior to Commercial Building Permit completion.
Municipal Projects
Requirements are specific to each municipal area
Please contact the appropriate municipal area for application requirements.
Wake County issues land disturbance permits for Garner, Morrisville, Rolesville, Wendell and Zebulon. You must have Plan Approval from the appropriate local government prior to Wake County land disturbance permit approval.
Wake County issues stormwater permits for Rolesville, Wendell and Zebulon. You must have Plan Approval from the appropriate local government prior to Wake County stormwater permit approval. Apply for the Wake County Stormwater Permit through the Permit Portal.
Stormwater completion is required prior to certificate of occupancy.