Building in the South Carolina Lowcountry is heavily regulated to protect the unique coastal environment. In unincorporated Charleston County, you cannot simply sketch a box on a piece of paper and get a building permit.
The Zoning and Planning Department requires an accurate site plan drawn to an engineer's scale. But more importantly, before you even think about setbacks, you have to look at the trees and the marshes.
Do You Need a Site Plan for a Small Permit in Charleston County?
Yes. If your project requires a zoning permit or building permit, you must submit a dimensional site layout plan.
The county specifically requires:
- Four (4) copies of an accurate, legible Site Plan drawn to an Engineer's Scale.
- Property lines with complete dimensions.
- Existing and proposed structures with their locations and square footage.
- Setbacks explicitly labeled.
- Parking areas dimensioned and paving materials noted.
- Grand Tree survey (if applicable).
- DHEC-OCRM Critical Line (if coastal/marshfront).
Who Runs Into This in Charleston County
- New residents who cut down a 26-inch oak tree to make room for a shed, completely unaware of the Grand Tree ordinance, resulting in massive fines.
- Coastal homeowners who submit a site plan for a pool, but have it rejected because the OCRM Critical Line signature on their plat is out-of-date.
- DIYers who sketch a deck layout using a standard architectural scale (like 1/4" = 1') instead of the required Engineer's Scale (like 1" = 20'), causing the county to reject the drawing.
- City of Charleston residents trying to navigate the county website, not realizing they are in incorporated city limits and must use the municipal permit office.
What Needs a Site Plan in Charleston County
- Fence permit site plan — Required if building an opaque fence for screening; site plan proves compliance with easements and rights-of-way.
- Shed permit site plan — Required for sheds over 120 sq ft. (Sheds 120 sq ft or less are exempt from zoning permits).
- Deck permit site plan — Required. Must show footprint, setbacks, and distance to any Grand Trees.
- Patio permit site plan — Required to calculate lot coverage and verify buffer zones.
- Pool permit site plan — Required. Must show pool, equipment, barriers, setbacks, and critical line buffers.
- Addition permit site plan — Required. A formal Site Plan Review is triggered if you increase the building footprint by more than 25%.
- Earth Disturbance — A Site Plan Review is required for any earth-disturbing activity equal to or greater than 5,000 square feet.
Why This Trips People Up in Charleston County
The Grand Tree Ordinance. This is the most unique and strictly enforced rule in Charleston County. Any tree measuring 24 inches or greater in diameter at breast height (DBH) is considered a "Grand Tree." Your site plan must include a survey showing all Grand Trees located within 40 feet of your project area. You must show tree barricades on the plan, and you must sign a Tree Affidavit. Removing a Grand Tree without approval is illegal. (Note: Pine trees and Sweet Gum trees are exempt from the Grand Tree definition).
Engineer's Scale. The county explicitly requires plans drawn to an Engineer's Scale (e.g., 1 inch = 10 feet, 1 inch = 20 feet, 1 inch = 50 feet). Many homeowners accidentally draw using an Architectural Scale (e.g., 1/4 inch = 1 foot), which is standard for floor plans but will often be rejected for a Charleston County site plan.
OCRM Critical Lines. If your property backs up to a marsh or saltwater wetland, the state Department of Health and Environmental Control (DHEC) establishes a coastal Critical Line. Your site plan must show this line, and the signature verifying it must be up-to-date (they expire). You cannot build within the required buffers of this line.
The 120 Square Foot Exemption. If you are building a one-story accessory structure (like a shed or playhouse) that is 120 square feet or less, you do not need a zoning permit.
Zoning and Setbacks in Charleston County
Setbacks are governed by the Zoning and Land Development Regulations Ordinance (ZLDR).
General Guidelines for Accessory Residential Structures:
- Front / Street Side: 25 feet minimum
- Interior Side: 15 feet minimum
- Rear: 25 feet minimum
- Accessory Structures (detached): 5 feet minimum from side/rear lines
Note: The Zoning and Planning Director may approve setback reductions of up to 15 feet if deemed compatible with existing development patterns, but this is never guaranteed.
How the Tool Handles This — 5 Steps
Our Site Plans Builder Tool loads Charleston County parcel data so you can generate the exact type of Engineer-scaled digital plan the county requires:
- Enter your address — Lot lines load directly from the county GIS data.
- Place your project — Add your deck, pool, or shed to the lot.
- Set the Engineer's Scale — The tool automatically generates a proportionate, scaled drawing to meet the county's Engineer's Scale requirement.
- Mark your Grand Trees — Use the tool's annotation features to drop markers for any 24"+ DBH trees within 40 feet of your project.
- Export a clean PDF — Download a professional plan ready to be emailed to siteplanreview@charlestoncounty.org or printed as the required 4 hard copies.
Where This Tool Fits — and Where It Doesn't
| Situation | Best path |
|---|---|
| Shed over 120 sq ft, deck, or standard addition | SitePlans.ai for the required Engineer-scaled site plan |
| Shed under 120 sq ft | SitePlans.ai to verify setbacks before you build without a permit |
| New single-family home | SC Licensed Surveyor/Design Professional legally required |
| City of Charleston limits | SC Licensed Surveyor legally required for city plot plans |
| DHEC-OCRM Critical Line properties | Licensed Surveyor required to obtain the updated critical line signature |
What This Doesn't Replace
SitePlans.ai helps create preliminary, conceptual site plans for residential projects where unincorporated Charleston County allows homeowner-prepared drawings. It is not a licensed land survey. If you are building a new single-family home, applying inside the incorporated City of Charleston, or need to establish a DHEC-OCRM Critical Line, you legally must hire a South Carolina licensed land surveyor or design professional.
Comparison: Your Options for a Charleston County Site Plan
| Method | Cost | Time | Stamp | Notes |
|---|---|---|---|---|
| Hand sketch | Free | 1–2 hrs | ✗ | Difficult to accurately draw to an Engineer's Scale by hand |
| SitePlans.ai | Free first plan | Minutes | ✗ | Automatically applies the required scale and allows tree annotations |
| CAD drafter | $300–$800+ | 1–2 weeks | Sometimes | Overkill for most accessory structures |
| Licensed surveyor | $500–$2,000+ | 2–4 weeks | ✅ | Mandatory for new homes, city limits, or marshfront properties |
| SitePlans.us (done-for-you) | Custom | 1–3 days | ✗ | Best if your first attempt was rejected by the Site Plan Review committee |
Common Mistakes That Delay Charleston County Permits
- Forgetting the Grand Trees — Submitting a plan without a tree survey, causing an immediate rejection from the Zoning Department.
- Wrong scale format — Submitting a site plan drawn at 1/4" = 1' (architectural scale) instead of 1" = 20' (engineer's scale).
- Outdated Critical Lines — Uploading an old plat for a marshfront property where the DHEC signature verifying the critical line has expired.
- Applying in the wrong jurisdiction — Using the county portal when the property is inside the City of Charleston, Mount Pleasant, or North Charleston.
- Missing the Tree Affidavit — Failing to sign and include the required Tree Affidavit with the site plan submission.
Support and Local Resources
- Charleston County Zoning and Planning — charlestoncounty.org
- Charleston County Building Services — charlestoncounty.org
- Charleston County GIS Parcel Viewer — ccgisapps.charlestoncounty.org — CRITICAL for verifying jurisdiction.
- SCDHEC OCRM — scdhec.gov (for critical line inquiries).
- FEMA Flood Maps — msc.fema.gov
Nearby Counties
- South Carolina permit site plan requirements
- [DavidsonCounty site plan guide]((counties/davidson-county-tn)) —
Frequently Asked Questions
1. Does the City of Charleston use the same permit rules as Charleston County?
No. While they share geography, the incorporated City of Charleston has its own building department and zoning rules. Furthermore, the City of Charleston explicitly requires site plans to be prepared, signed, and sealed by a SC licensed land surveyor or design professional, whereas the unincorporated county sometimes allows homeowner drawings for accessory structures.
2. What is a Grand Tree in Charleston County?
A Grand Tree is any tree (except pine or sweet gum) that measures 24 inches or greater in diameter at breast height (DBH). Your site plan must show all Grand Trees within 40 feet of your project.
3. Do I need a permit for a shed in Charleston County?
If the shed is a one-story accessory structure that is 120 square feet or less, it is exempt from a zoning permit. If it is larger than 120 square feet, a permit and an engineer-scaled site plan are required.
4. What is the difference between an Engineer's Scale and an Architectural Scale?
An architectural scale uses fractions of an inch to represent feet (e.g., 1/4 inch = 1 foot). An engineer's scale uses whole numbers (e.g., 1 inch = 10 feet, or 1 inch = 20 feet). Charleston County site plans must use an engineer's scale.
5. What is the DHEC-OCRM Critical Line?
It is a state-regulated boundary along coastal waters and tidelands (marshes). If your property touches this area, your site plan or plat must show the critical line, and the state's signature verifying that line must be current, as marshes move over time.
6. Can I use SitePlans.ai for a Charleston County permit?
Yes. For residential accessory projects in the unincorporated county that do not touch the critical line, SitePlans.ai allows you to create an Engineer-scaled PDF site plan, complete with annotations for your Grand Trees.
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Start Your Charleston County Site Plan
Check your jurisdiction on the Charleston County GIS first. If you are in the unincorporated county, enter your address below to pull your property lines, place your project, annotate your Grand Trees, and download the Engineer-scaled PDF you need for your permit application.
Build My Charleston County Site Plan →
Got a correction notice from the Zoning and Planning Department? Send the comments to SitePlans.us and we'll draft the revision for you.
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