Georgia Wind Zone Map for Roofing

Understanding the ASCE 7-16 Wind Speed Map for Georgia

The wind speed that governs your roofing installation comes from ASCE 7-16, "Minimum Design Loads and Associated Criteria for Buildings and Other Structures," published by the American Society of Civil Engineers. The International Residential Code (IRC) references these wind speed maps to determine the design criteria for residential roofs across the United States. Georgia's building code, managed by the Georgia DCA with state amendments, adopts these maps as the basis for wind resistance requirements.

ASCE 7-16 maps display "ultimate design wind speeds," measured as 3-second gust speeds at 33 feet above ground in Exposure Category C (open terrain). These numbers represent the wind speed that a building's components and cladding must resist over the structure's design life. The maps assign a specific wind speed to every geographic coordinate in the country, creating contour lines that define wind zones.

Georgia spans a wide range of wind speeds. The northwestern mountains see design speeds around 110-115 mph. Metro Atlanta and the central portion of the state sit at 115-120 mph. Southern Georgia interior regions range from 115-125 mph. The coastal counties from Savannah to the Florida border face 130-150+ mph design speeds, reflecting hurricane exposure from the Atlantic Ocean.

These wind speeds do not represent the maximum wind your area will experience. They represent the statistical wind speed with a specific probability of occurrence during the building's design life. A 115 mph design speed means there is approximately a 7% probability of that wind speed being reached or exceeded during a 50-year period. The numbers account for geography, terrain, proximity to the coast, and historical wind data.

For homeowners, the practical impact is straightforward: your location on the wind speed map determines which shingles, which fastener patterns, which underlayment attachment methods, and which structural connections your roof requires to meet Georgia building code.

Georgia's Three Wind Regions and What They Mean for Roofing

Georgia divides into three broad wind regions based on ASCE 7-16 contour lines. Each region carries different requirements for roofing materials, installation methods, and structural connections.

Mountain Region: 110-115 mph

The mountain counties of north Georgia, including Fannin, Union, Towns, Rabun, Gilmer, and Pickens counties, sit in the lowest wind zone in the state. Design speeds range from 110-115 mph. This zone allows standard fastener patterns and material ratings for most residential roofing applications. However, elevation and terrain effects can create localized wind acceleration around ridges and gaps that may warrant additional measures for specific building sites.

Metro Atlanta and Central Georgia: 115-120 mph

The broad central band of Georgia, including the entire metro Atlanta area, falls in the 115-120 mph zone. This is the zone that governs roofing installations in Alpharetta, Buckhead, Johns Creek, Marietta, Roswell, Sandy Springs, Lawrenceville, and every community within a 30-mile radius of Atlanta.

At 115-120 mph, asphalt shingles must carry wind resistance ratings of ASTM D7158 Class G (120 mph) or ASTM D3161 Class F (110 mph) with appropriate fastener schedules. Most architectural shingles from GAF and CertainTeed meet or exceed these ratings. The key variable is the fastener pattern: a 4-nail pattern satisfies the minimum code requirement in this zone, but a 6-nail pattern provides superior hold-down strength and is required for enhanced wind warranty coverage from both manufacturers.

Coastal Georgia: 130-150+ mph

Georgia's coastal counties face design wind speeds of 130-150+ mph, reflecting direct hurricane exposure. Chatham County (Savannah) sits at approximately 130-140 mph. The barrier islands and immediate coastline can reach 150 mph or higher. This zone requires shingles rated to ASTM D7158 Class H (150 mph), 6-nail fastener patterns as a minimum, enhanced underlayment attachment, and structural connections (hurricane clips or straps) that tie the roof assembly to the wall framing.

While coastal requirements do not apply to metro Atlanta, they illustrate how wind speed drives every aspect of a roofing installation. The same principles that protect coastal homes from hurricanes protect inland homes from severe thunderstorms, tornadoes, and tropical storm remnants that track through central Georgia.

Ultimate Design Wind Speeds for Georgia Cities

The following table lists ASCE 7-16 ultimate design wind speeds for cities across Georgia. These values apply to Risk Category II buildings (standard residential construction). Values represent the 3-second gust speed at 33 feet above ground in Exposure Category C.

For metro Atlanta homeowners, note that every city in the service area falls within the 115-120 mph range. This means the same shingle ratings, fastener patterns, and installation methods apply across our 30-mile service radius. You do not need different materials for a project in Roswell versus Marietta.

City	County	Wind Speed (mph)	Region
Atlanta	Fulton	115	Metro Atlanta
Alpharetta	Fulton	115	Metro Atlanta
Roswell	Fulton	115	Metro Atlanta
Johns Creek	Fulton	115	Metro Atlanta
Sandy Springs	Fulton	115	Metro Atlanta
Buckhead	Fulton	115	Metro Atlanta
Marietta	Cobb	115	Metro Atlanta
Lawrenceville	Gwinnett	115	Metro Atlanta
Decatur	DeKalb	115	Metro Atlanta
Duluth	Gwinnett	115	Metro Atlanta
Gainesville	Hall	115	North Georgia
Dahlonega	Lumpkin	110	Mountain
Blue Ridge	Fannin	110	Mountain
Macon	Bibb	115	Central Georgia
Augusta	Richmond	120	East Georgia
Columbus	Muscogee	115	West Georgia
Valdosta	Lowndes	120	South Georgia
Savannah	Chatham	140	Coastal
Brunswick	Glynn	145	Coastal
St. Simons Island	Glynn	150	Coastal
Tybee Island	Chatham	150	Coastal

Wind speeds increase as you move from the mountains toward the coast. The jump from 120 mph in Augusta to 140 mph in Savannah reflects the transition from inland thunderstorm exposure to coastal hurricane exposure. This jump triggers significant changes in roofing requirements, including mandatory enhanced fastener patterns, impact-rated materials, and structural connection requirements.

How Wind Zones Drive Material Selection and Fastener Patterns

Your position on the wind speed map creates a chain of requirements that flows from the ASCE 7 map through the IRC, through manufacturer specifications, and onto your roof. Each link in the chain must be satisfied for the installation to meet code and maintain warranty coverage.

Shingle Wind Resistance Ratings

The IRC requires asphalt shingles to carry wind resistance ratings that meet or exceed the design wind speed for the installation location. Two ASTM test methods establish these ratings:

• ASTM D3161 assigns Class F (110 mph), Class G (120 mph), or Class H (150 mph) ratings based on a fan-forced wind test.
• ASTM D7158 assigns Class D (90 mph), Class G (120 mph), or Class H (150 mph) ratings based on a mechanical uplift test that better simulates real-world wind forces.

For metro Atlanta's 115 mph zone, shingles must carry at least ASTM D7158 Class G or ASTM D3161 Class F. GAF Timberline HDZ shingles carry ASTM D3161 Class F and ASTM D7158 Class H ratings, exceeding the metro Atlanta requirement. CertainTeed Landmark shingles carry similar ratings. Both manufacturers' premium product lines meet or exceed requirements for every wind zone in Georgia.

Fastener Pattern Requirements

Fastener patterns scale with wind speed. The IRC and manufacturer specifications define two standard patterns:

• 4-nail pattern: Four nails per shingle strip, placed in the manufacturer's designated nailing zone. This satisfies the minimum code requirement for the 115-120 mph zone when paired with appropriately rated shingles.
• 6-nail pattern: Six nails per shingle strip. Required in zones above 120 mph and recommended by both GAF and CertainTeed for enhanced wind warranty coverage in all zones. Increases hold-down strength by approximately 50% over the 4-nail pattern.

1 Source Roofing uses the 6-nail pattern on every installation regardless of wind zone. The additional material cost is minimal. The performance improvement is significant. And the enhanced wind warranty coverage from both GAF and CertainTeed provides homeowners with stronger protection against wind damage claims. See our wind speed requirements guide for detailed fastener specifications.

Underlayment Attachment in Wind Zones

Underlayment must remain attached to the roof deck under wind loading. In standard wind zones, cap nails at 6-inch spacing along overlaps and 12-inch spacing in the field satisfy code. In higher wind zones, the spacing tightens and some manufacturers require adhesive-backed (self-adhering) underlayment at eaves, rakes, and ridges where wind uplift forces are highest. Proper underlayment attachment prevents wind-driven rain infiltration if shingles are displaced during a storm.

Exposure Categories and Roof Pressure Zones

Wind speed alone does not determine the forces acting on your roof. Two additional factors modify the effective wind load: the exposure category of your building site and the pressure zone location on the roof surface.

ASCE 7 Exposure Categories

ASCE 7 defines three exposure categories for wind loading calculations:

• Exposure B: Urban and suburban areas, wooded areas, or terrain with numerous obstructions the size of single-family homes or larger. Most residential sites in metro Atlanta fall into Exposure B.
• Exposure C: Open terrain with scattered obstructions. Rural areas, open fields, and properties near large bodies of open water. This is the baseline exposure used for the wind speed maps.
• Exposure D: Flat, unobstructed coastal areas exposed to wind flowing over open water for at least 1 mile. Applies to Georgia's barrier islands and immediate coastline.

Exposure B produces lower wind pressures than Exposure C for the same design wind speed, because surrounding buildings and trees reduce wind velocity at the roof level. Most homes in Alpharetta, Johns Creek, Buckhead, and other established neighborhoods qualify for Exposure B. A home on an open hilltop or at the edge of a large open area may require Exposure C calculations.

Roof Pressure Zones: Field, Edge, and Corner

Wind does not apply equal pressure across the entire roof surface. ASCE 7 divides the roof into three pressure zones with increasing wind forces:

• Field zone (Zone 1): The central area of the roof. Experiences the lowest wind uplift pressures. Standard fastener patterns apply here.
• Edge zone (Zone 2): The perimeter strips along eaves and rakes. Wind accelerates as it flows around building edges, creating higher uplift forces. Enhanced fastener patterns or additional adhesive may be required.
• Corner zone (Zone 3): The corner areas where two edges meet. Experiences the highest wind uplift pressures on the roof. Some manufacturers require 6-nail patterns or supplemental adhesive in corner zones even when 4-nail patterns satisfy the field zone.

The combination of design wind speed, exposure category, and pressure zone determines the actual uplift force at each point on your roof. A qualified contractor accounts for all three when selecting materials and fastener patterns. This is one reason 1 Source Roofing uses the 6-nail pattern across the entire roof: it eliminates the risk of under-fastening in edge and corner zones where wind forces concentrate.

"ASCE 7 divides every roof into three pressure zones. Corner zones experience up to 2.5x the uplift force of the field zone. A 6-nail pattern across the full roof surface covers the worst-case zone by default."

How Wind Zones Connect to Other Georgia Roofing Code Requirements

Wind zone requirements do not exist in isolation. They connect to every other aspect of Georgia's roofing code, creating an integrated system where each component must work together to resist wind forces.

Drip edge: Drip edge at eaves and rakes provides a finished edge that prevents wind from lifting the shingle starter course. In higher wind zones, drip edge must be face-nailed at 4-inch spacing rather than the standard 12-inch spacing. Even in metro Atlanta's moderate wind zone, proper drip edge installation is critical because eaves and rakes are edge pressure zones where wind uplift forces are highest.

Flashing: Flashing at wall intersections, chimneys, and penetrations must resist wind-driven rain. In high wind zones, step flashing dimensions increase and counter flashing attachment requirements tighten. Our chimney flashing guide and flashing installation guide cover the specific requirements for metro Atlanta.

Ventilation: Ridge vents and other exhaust vents must resist wind uplift while maintaining airflow. Wind-driven rain can enter through vents during storms if the vent product does not incorporate baffles or weather filters. Vent selection in wind-exposed locations requires attention to both ventilation performance and wind resistance.

Structural connections: In coastal wind zones, the IRC requires structural connections (hurricane clips or straps) that tie the roof framing to the wall framing. While metro Atlanta does not require these connections under the current code, they represent a valuable upgrade for homeowners who want maximum wind resistance. When a structural engineer evaluates a roof, they assess these connections as part of the overall wind resistance system.

Re-roofing considerations: When re-roofing a home in any wind zone, the new installation must meet the current wind speed requirements, not the code that was in effect when the original roof was installed. A home built in 1990 under older wind speed maps gets re-roofed to current ASCE 7-16 standards. This sometimes means upgrading from a 4-nail to a 6-nail pattern or selecting higher-rated shingles than the original installation used.

Wind-Rated Roofing Installation from 1 Source Roofing

Every residential roof in metro Atlanta must resist 115-120 mph design wind speeds. Meeting this requirement depends on material selection, fastener patterns, underlayment attachment, and proper installation at every detail point where wind forces concentrate.

1 Source Roofing approaches wind resistance as a system, not a checklist. We select shingles that exceed the design wind speed for your location. We use 6-nail patterns on every installation. We attach underlayment with appropriate fastener spacing. We install drip edge, flashing, and ridge vents with attention to wind resistance at every connection point.

As a GAF Certified and CertainTeed Certified contractor, we install materials that carry the highest wind resistance ratings available. GAF Timberline HDZ with LayerLock technology achieves ASTM D7158 Class H (150 mph), exceeding metro Atlanta's 115 mph requirement by a wide margin. CertainTeed Landmark carries equivalent ratings. Both manufacturers back their products with enhanced wind warranty coverage when installed by a certified contractor using the 6-nail pattern.

If storm damage has affected your roof, or if you are planning a roof replacement, call us at (404) 277-1377 for a free inspection. We serve Alpharetta, Buckhead, Johns Creek, Marietta, Roswell, Sandy Springs, and every community within a 30-mile radius of Atlanta.

Wind Zone Guides and Roofing Services