Research by DoINeedAPermit Research Team · Updated May 2026
The Short Answer
Any attached deck in St. Marys requires a permit unless it is freestanding, ground-level, and under 200 square feet. Even small attached decks need ledger-flashing plans and footing details.
St. Marys enforces Georgia State Building Code (currently adopting the 2012 IBC with amendments) through the City of St. Marys Building Department. The critical local twist: St. Marys sits in the Coastal Plain and Piedmont transition zone with 12-inch frost depth and sandy/clay soils—both of which mean footing depth requirements are non-negotiable on plan review. Additionally, because St. Marys is within the Coastal Zone Management Act jurisdiction (Camden County), decks near tidal marshes or within mapped coastal setback zones may trigger additional environmental review and setback spacing. The city's online portal and plan-review process are accessed through the municipal portal, and most attached decks (any deck ledger-attached to the house) require structural review, framing inspection, and final sign-off—not over-the-counter approvals. Unlike some nearby unincorporated areas, St. Marys does not grant blanket exemptions for small attached decks; the attachment point itself triggers the permit requirement.

What happens if you skip the permit (and you needed one)

St. Marys attached deck permits — the key details

St. Marys enforces the Georgia State Building Code, which incorporates the 2012 International Building Code (IBC) with state amendments. The critical rule is IRC R507.9: any deck attached to a house via a ledger board must have flashing that prevents water intrusion into the house rim band. In St. Marys' warm, humid climate (CZ 3A), this ledger flashing is absolutely non-negotiable because standing water rots the band board and rim joist within 2–3 years. The city's Building Department will reject any deck plan that doesn't show flashing details—typically a minimum 2-inch overhang from the top of the ledger, extending down to below the rim and folded up behind the rim siding. Many homeowners skip this detail because it seems cosmetic; the city will not sign off. Second, footing depth in St. Marys is 12 inches minimum below grade to avoid frost heave (even though southern frost lines are shallow, the clay-sand transition soils here shift). All footing details—hole depth, diameter, concrete specs, and post-to-footing attachment—must be shown on the plan.

The second major local angle is coastal setback and environmental review. St. Marys is in Camden County, which falls under Georgia's Coastal Zone Management Act. If your deck is within 1,000 feet of a tidal marsh or within mapped coastal setback zones (typically landward of the mean high water line of the Intracoastal Waterway or St. Marys River), the city may require a Coastal Zone Management Permit from the Department of Natural Resources before the Building Department issues the deck permit. This adds 2–3 weeks to the timeline and an extra $100–$300 fee. The city's Building Department staff can tell you immediately if you're in the zone; bring your legal description or address. If you are in the zone, you'll need both a local deck permit and a state CZM permit—a two-step process that many homeowners don't anticipate.

Guardrail height and stair geometry are the third common pain point. Georgia Code (following IBC 1015) requires guards on decks over 30 inches high. The guard must be 36 inches minimum from deck surface to the top of the rail (measured vertically). The infill (spindle spacing or mesh) must not allow a 4-inch sphere to pass through. Stair stringers must have treads no less than 10 inches (nosing to nosing) and rise no more than 7.75 inches per step. Landing dimensions must be no less than 36 inches deep in the direction of travel. Many homeowners buy pre-fab stairs that don't match these dimensions and have to rebuild or re-engineer them on the plan. The city will call this out in the first plan review; budget extra time if your stair design is off-the-shelf.

Beam-to-post connections and lateral-load devices are the fourth detail that trips up DIY plans. IRC R507.9.2 requires positive lateral-load attachment between the beam and posts—not just gravity. This typically means Simpson DTT (deck-to-timber) lateral ties or equivalent metal hardware rated for the loads. Many homeowners show bolts or nails alone, which does not satisfy the code. The plan must specify the hardware by model number (e.g., 'Simpson DTT4 ties, four per post'). The Building Department will ask for this detail if you've omitted it; it's a cheap fix (about $20–$40 per post) but must be in the plan before the city will issue the permit.

Finally, the permit fee and timeline. St. Marys charges based on estimated valuation, typically 1.5–2% of the deck cost. A $6,000 deck costs $90–$120 in permit fees (plus $25–$50 inspection fees for framing and final). The plan review takes 2–4 weeks depending on whether it's over-the-counter (rare for attached decks) or goes to the structural engineer on staff. Inspections are three-point: footing before pour, framing before fastening, and final after rails and stairs are complete. If the city finds a code violation during framing inspection, work must stop until it's corrected. The typical timeline from permit application to final approval is 6–8 weeks, including plan review and three inspections.

Three St. Marys deck (attached to house) scenarios

Scenario A
12-foot by 16-foot attached deck, 18 inches above grade, rear yard, Oswego subdivision—wood frame, no stairs, no electrical
A 192-square-foot deck that is 18 inches above grade is below the 200-square-foot threshold BUT is attached to the house (ledger board), which automatically requires a permit in St. Marys. The deck is under 30 inches, so guardrails are not required by code, but the ledger flashing and footing details are mandatory on the plan. Because Oswego is not in a mapped coastal zone, you do not need a separate state CZM permit. The footing depth in this Piedmont clay soil (Cecil series) is 12 inches minimum below grade, and you'll need to show footing layout—either two rows of posts (or three, depending on beam span and live load) with 12-inch holes, 10-inch diameter minimum, concrete-filled. The ledger board attaches directly to the rim band of the house; the plan must show 2x6 rim ledger with flashing extending behind the house siding and down 1 inch below the rim joist. Fastening is 3/8-inch bolts or lag screws, 16 inches on center, with joist hangers or equivalent connection hardware. Plan review is typically 2–3 weeks; footing inspection (before pour) is about 1 week after permit issuance; framing inspection is 2–3 days after construction starts; final is same-day or next day. Total permit fee is approximately $120–$150 (at 2% of $6,000–$7,500 valuation). You do not need stairs, so you avoid stringer code and landing dimensions; this is the simplest attached-deck scenario.
Permit required (attached ledger) | 12-inch frost depth | Footing pre-pour inspection | Framing and final inspections | $120–$150 permit fee | No guardrail required (under 30 inches) | Plan review 2–3 weeks | No coastal zone review needed
Scenario B
16-foot by 20-foot elevated deck, 42 inches above grade, with 8 wood stairs and metal guardrail—riverside property near St. Marys River, no electrical
A 320-square-foot deck at 42 inches high definitely triggers the permit requirement (over 30 inches, over 200 sq ft, attached). This scenario showcases the coastal setback and environmental review angle. Riverside properties in St. Marys within 1,000 feet of the St. Marys River are almost always in the Coastal Zone Management Act jurisdiction. Before the City Building Department will issue the deck permit, you must obtain a Coastal Zone Management Permit from the Georgia Department of Natural Resources (DNR). This adds 3–4 weeks and a $100–$300 fee. The DNR will review whether the deck location, footprint, and proximity to marsh or river comply with setback rules (typically 25–100 feet, depending on habitat type). Assuming the DNR approves, the City Building Department plan review must include footing details (12-inch depth minimum in sandy coastal-plain soils), ledger flashing, guardrail design (36-inch height minimum, 4-inch infill), and stair geometry. The stairs are 8 risers at 5.25 inches per rise (42 inches ÷ 8 = 5.25 inches, compliant). Each stair tread must be 10 inches deep (nose to nose) and treads must not vary by more than 3/16 inch. The landing below the stairs must be 36 inches deep. Guardrail height is 36 inches measured from the deck surface; the rail must reject a 4-inch sphere at all points. Metal balusters (1.5-inch spacing) are typical and compliant. Beam-to-post connections must show Simpson DTT or equivalent lateral-load hardware (four ties per post minimum at 42-inch height). Permit valuation is approximately $12,000–$15,000 (complex deck, stairs, higher risk); permit fee is $180–$300. Plan review is 3–4 weeks (coastal review adds time). Inspections are footing (before pour), framing (before fastening), and final. Total timeline: 10–12 weeks (including DNR review).
Permit required (attached, over 30 inches, over 200 sq ft) | Coastal Zone Management Permit required (DNR, 3–4 weeks, $100–$300) | 12-inch frost depth, sandy soil | Guardrail 36 inches required | Stair treads 10 inches, rise 5.25 inches | Metal balusters, 1.5-inch spacing | Simpson DTT lateral ties per post | $180–$300 permit fee, City | Plan review 3–4 weeks (DNR adds time) | Three inspections (footing, framing, final)
Scenario C
10-foot by 12-foot low-platform ground-level deck, 6 inches above grade, no stairs, freestanding (no ledger attachment), Woodentop community
A freestanding ground-level deck under 200 square feet (10 × 12 = 120 sq ft) and under 30 inches high (6 inches) is exempt from the permit requirement under Georgia Code and IRC R105.2. Because this deck is NOT attached to the house (no ledger board), it is freestanding and therefore falls into the exemption category. However, the exemption comes with an important caveat: if you ever upgrade this deck later—adding a ledger attachment to the house, raising it to 24 inches, or expanding it beyond 200 sq ft—you will lose the exemption and must pull a permit retroactively. Additionally, your HOA (if Woodentop is an HOA community) may have separate approval requirements, so check your covenants before construction. For a freestanding ground-level platform, you do not need to file with the City Building Department, but you should keep construction notes (footing photos, post spacing, fastener types) in case the city later questions the work. Use 12-inch minimum frost-depth footings (below grade) to avoid heave in the clay-sand soils; pressure-treated posts (UC4B or better) are recommended for longevity in Georgia's humid climate. Typical cost is $1,500–$3,000 materials only, no permit fees.
No permit required (freestanding, under 200 sq ft, under 30 inches) | Exempt under IRC R105.2 | Check HOA covenants separately (may require approval) | 12-inch frost-depth footings still recommended | Use PT lumber UC4B or better | No inspections required | $0 permit fee | Typical cost $1,500–$3,000 materials only

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Ledger flashing and rot prevention in St. Marys' humid climate

St. Marys is in IECC Climate Zone 3A (warm-humid), which means high rainfall, standing water risk, and fungal decay pressure on wood. The ledger board—the 2×6 or 2×8 that bolts directly to the house rim joist—is the most rot-prone component because water pools where it meets the siding. IRC R507.9 requires flashing, but the local climate makes this even more critical. Georgia-adopted code specifies a minimum 2-inch metal flashing that starts at the top of the ledger, extends down the back (face) of the ledger, and wraps down below the house rim joist by at least 1 inch, then folds up behind the house siding or bands. The flashing must be Step flashing (overlapping shingles or siding) or fully sealed with backer rod and sealant. Many DIY plans show a single L-flashing; the city will reject this and require a more robust design. Typical detail shows the flashing as part of a full-section drawing (rim band, ledger, flashing, footing) that the Building Department approves before work starts.

If flashing is installed incorrectly or omitted, water infiltrates the rim band and rim joist within 1–2 years in the humid climate. This causes the wood to soften, fasteners to pull out, and the deck to separate from the house—a safety hazard and a structural failure. The Building Department requires photographic proof of correct flashing installation before signing off the framing inspection. If flashing is found to be missing or non-compliant at final inspection, the city will issue a correction order and the deck will not be approved until it is fixed. Correcting a flashing problem after the deck is built is extremely difficult and costly (often $2,000–$4,000 in contractor time and material rework), so getting it right on the plan and in the first inspection is essential.

For decks that remain unpermitted and developed without proper flashing, the long-term cost of rot repair—rim joist replacement, band board replacement, structural re-sistering—can exceed $8,000–$12,000. The homeowner's insurance will not cover this if the work was unpermitted; it's treated as a pre-existing condition or defect. When selling, the Residential Property Disclosure Statement must flag unpermitted work; the buyer's home inspector will identify rot and demand repair before closing.

Coastal Zone Management review and timeline impact

St. Marys' location in Camden County places it under Georgia's Coastal Zone Management Act (CZMA) for properties within mapped coastal areas. The relevant zone includes lands within 1,000 feet of tidal marshes, estuaries, and major rivers such as the St. Marys River, Crooked River, and Satilla River, as well as the Intracoastal Waterway. If your property address falls within this zone, any development—including a deck—requires a separate Coastal Zone Management Permit from the Georgia Department of Natural Resources (DNR) before the City Building Department will issue the local permit. The DNR review examines whether the deck footprint, pilings, grading, and proximity comply with saltwater-marsh protection rules (setbacks, no dredge spoil on protected areas, vegetation impact). This review typically takes 3–4 weeks and costs $100–$300. The City Building Department can tell you in 10 minutes whether your address is in the zone; if it is, you must submit the DNR application concurrently with or before the local deck permit application. Delaying this step will delay your local permit by 4 weeks, so the two-step process must be planned from the start.

For inland (non-coastal) properties in St. Marys—typically north and west of downtown, in areas like Oswego subdivision and Woodentop—the CZMA does not apply, and you only need the local City Building Department permit. Knowing your property's coastal status is the first question to ask the Building Department. If you are in doubt, provide your address or legal description to the city or DNR and ask for a coastal-zone determination letter (free, takes 5–10 business days). This single step will clarify whether you face a one-step local permit or a two-step local plus DNR process. Many homeowners have been surprised by a 4-week delay because they didn't know they were in the coastal zone; planning for this upfront avoids frustration.

If your deck is approved by the DNR, that approval is added to the City Building Department plan file and does not require re-review. The city's Building Department process (footing, framing, final inspections) proceeds on the same timeline as non-coastal decks. The coastal-zone permit is a gating item—you cannot start construction without it—but once approved, it is a one-time document.

City of St. Marys Building Department
St. Marys City Hall, St. Marys, Georgia (exact address in online portal or 912-576-3211)
Phone: 912-576-3211 or check municipal portal for building-specific line | https://www.ci.st-marys.ga.us/ (check municipal portal for permit application link)
Monday–Friday, 8:00 AM–5:00 PM (verify locally; may be closed holidays)

Common questions

Do I need a permit for a small attached deck in St. Marys?

Yes. Any deck attached to your house via a ledger board requires a permit in St. Marys, regardless of size. The attachment point itself triggers the requirement because it involves structural connection to the house rim band and requires flashing inspection per IRC R507.9. Only freestanding, ground-level decks under 200 square feet are exempt. If your deck is attached, you need a permit.

What is the frost-depth footing requirement for decks in St. Marys?

Footings must extend 12 inches below finished grade in St. Marys. This accounts for the clay-sand transition soils (Cecil series and Coastal Plain sandy soils) and prevents frost heave and settling. Even though St. Marys is in a warm zone, the 12-inch depth is enforced by Georgia State Building Code and the City Building Department. All footing detail drawings must show this depth; the Building Department will inspect before concrete is poured.

How long does the deck permit process take in St. Marys?

Plan review takes 2–4 weeks for simple attached decks; add 3–4 weeks if your property is in the Coastal Zone and requires a DNR permit. After the city approves the plan, construction can begin. Inspections (footing, framing, final) typically take 1–2 weeks. Total timeline is 6–8 weeks for inland properties, 10–12 weeks for coastal properties. Starting the coastal-zone check early saves time.

Do I need a coastal-zone permit for my St. Marys deck?

Only if your property is within the mapped Coastal Zone Management Area (within 1,000 feet of tidal marsh, river, or Intracoastal Waterway). Downtown St. Marys and river-front properties typically are; inland subdivisions usually are not. The City Building Department can tell you immediately if you are in the zone. If you are, you must obtain a Georgia DNR Coastal Zone Management Permit before the city will issue the local deck permit. This adds $100–$300 and 3–4 weeks.

What does ledger-flashing detail need to show on the deck plan?

The detail must show the 2×6 or 2×8 ledger bolted to the house rim band, with a metal flashing (minimum 2-inch width) that extends down the back of the ledger, wraps below the rim joist, and tucks behind the house siding or bands. Fastening is typically 3/8-inch lag bolts or screws, 16 inches on center. Step flashing where ledger meets siding is required. The City Building Department will provide a standard detail or accept a plan-stamped section. This detail is non-negotiable for plan approval.

Do I need guardrails on my St. Marys deck?

Yes, if the deck surface is more than 30 inches above grade. The guardrail must be at least 36 inches high (measured from the deck surface to the top of the rail) and must be designed to reject a 4-inch sphere at all points. Spindle spacing, balusters, or mesh infill must not allow a 4-inch ball to pass. If your deck is under 30 inches high, guardrails are not required by code, though local HOA rules may differ.

Can I hire a contractor to pull a deck permit, or must I do it myself?

You can hire a contractor, architect, or engineer to prepare and submit plans on your behalf. Georgia Code § 43-41 allows owner-builders (homeowners) to pull permits for work on their own primary residence, but most people hire contractors who have experience with local plan review and inspection processes. Either way, the City Building Department will work with whoever submits the application. If you are an owner-builder, you are responsible for complying with all code and inspection requirements yourself; the city will still conduct the same inspections.

What is the permit fee for a deck in St. Marys?

Permit fees are typically 1.5–2% of the estimated valuation of the work. A $6,000 deck costs $90–$120; a $12,000 deck costs $180–$240. Add inspection fees (usually $25–$50 per inspection, or a flat fee of $75–$100 for all three inspections). Check the current fee schedule with the City Building Department or online portal. Fees are separate from any DNR coastal-zone permit fees ($100–$300 if applicable).

What happens if I build a deck without a permit in St. Marys?

If discovered, the city will issue a stop-work order and a fine of $500–$1,500, depending on scope and duration of unpermitted work. You may be ordered to remove the deck or bring it into compliance through a retroactive permit and reinspection (which costs more and may require design changes). At resale, unpermitted work must be disclosed on the Georgia Residential Property Disclosure Statement, and buyers can back out or demand price reduction. Insurance may deny coverage for damage related to unpermitted structural work. The long-term costs of avoiding the permit usually exceed the permit fee and timeline.

Are there exemptions for freestanding ground-level decks in St. Marys?

Yes. A freestanding deck (not attached to the house) that is under 200 square feet and under 30 inches above grade is exempt from the permit requirement under IRC R105.2 and Georgia Code. However, check your HOA covenants if applicable; the HOA may require approval separately. If you later attach the deck to the house (add a ledger) or raise it, you will lose the exemption and must pull a permit. Use proper 12-inch frost-depth footings and pressure-treated lumber (UC4B) for durability in the humid climate, even though no permit is required.

Disclaimer: This guide is based on research conducted in May 2026 using publicly available sources. Always verify current deck (attached to house) permit requirements with the City of St. Marys Building Department before starting your project.