GEORGIA · CHATHAM COUNTY / CITY OF SAVANNAH
River-City Squares Built to Stand the Atlantic's Hurricane Reach
Where the Savannah River meets low-country marsh, design pressure rides in on coastal gusts. Here is what Chatham County permitting and ASCE 7-22 ask of every structure.
COASTAL VELOCITY · EXPOSURE READ
Why the Coast Pushes Savannah's Numbers Up
Tybee's open Atlantic front sits at the top of the band; the moss-draped historic squares sit lower — the river estuary blurs the line between them.
Atlantic Front — Tybee & the Sound
Direct ocean exposure pulls the design gust toward the upper 125–130 mph edge under open-water Exposure C.
EXPOSURE CLive-Oak Canopy — the Inland Squares
Dense urban fabric west of the river can justify Exposure B, settling projects nearer the 120–125 mph floor.
EXPOSURE BEstuary Reach — River & Port
Open water along the Savannah River carries coastal exposure well inland to Garden City and the port terminals.
SITE-SPECIFICRead the band, not a single number. Savannah's 3-second-gust design speed runs 120–130 mph for Risk Category II and shifts with your exact address and terrain — never assume one fixed mph for the whole county.
ASCE 7-22 · TABLE 1.5-1 MAP SELECTION
How Occupancy Re-Maps Your Design Speed
Risk category never multiplies a number — it sends you to a longer-return-period map, and that map reads higher over coastal Chatham County.
| Risk Category | Map / Return Period | Typical Savannah Structures |
|---|---|---|
| I | 300-year MRI (lowest) | Marsh storage sheds, minor agricultural & temporary structures |
| II | 700-year MRI · 120–130 mph | Homes, shops, most downtown and southside occupancies |
| III | 1,700-year MRI (higher) | Schools, large assembly, hazardous-materials facilities |
| IV | 3,000-year MRI (highest) | Memorial Health, fire stations, EOCs, hurricane shelters |
PERMIT-READY CHECKLIST
What Chatham County Needs Before You Break Ground
Every sealed wind-load package for a Savannah permit pulls these pieces together — coastal exposure and the historic district add the local twist.
Site Wind Speed
Address-derived V from ASCE 7-22 maps, stated for the project Risk Category.
3-SEC GUSTExposure Call
C for Tybee, the river front and the port; B may apply behind the inland canopy.
C / BRisk Category
Table 1.5-1 classification with documentation of occupancy and use.
I–IVMWFRS & C&C
Main-frame and component-and-cladding pressures for walls, roof and openings.
FULL ASCE 7-22Historic-District Fit
Concealed shutters & uplift retrofits cleared by the Historic Review Board.
22 SQUARESGeorgia PE Seal
Calculations sealed by a Professional Engineer or Architect licensed in Georgia.
REQUIREDWHY IT MATTERS HERE
Lessons the Low Country Already Learned
Matthew (2016) made landfall as a Category 1 near the coast and flooded the riverfront; Irma (2017) brought tropical-storm winds the next year. Both proved that uplift detailing and preservation-friendly shutters protect Savannah's irreplaceable fabric.
Spanish moss does not count. Canopy may soften gusts in the squares, but it can never be credited in a wind-load calculation — the structure carries the full design pressure.
EXPLORE THE NETWORK
Georgia Codes & Official Chatham Resources
Statewide context and the offices that enforce it along the coast.
Georgia Statewide
How the Peach State adopts ASCE 7-22 across its regions.
STATE GUIDEAll States
Compare adopted editions and wind maps nationwide.
DIRECTORYSpeed by Location
Look up design wind speed for any address.
MAP TOOLHistoric Savannah Foundation
Preservation-compliant wind mitigation guidance.
PRESERVATIONRUN THE NUMBERS
Calculate Savannah Loads in Minutes, Not Hours
Enter a Chatham County address and the calculator pulls the right 120–130 mph band, exposure read, risk-category map and C&C pressures — PE-ready for permit.