Wind Speed Roofing Code in Georgia

Georgia's Wind Speed Design Requirements

Georgia adopts the International Residential Code (IRC), which references ASCE 7-16 wind speed maps for structural design. These maps assign an ultimate design wind speed to every location in the state. The number represents the three-second gust speed a structure must withstand during its 50-year design life.

Metro Atlanta falls in the 115 to 120 mph zone. Coastal Georgia sees higher ratings. The Savannah area reaches 140 mph, and barrier islands push past 150 mph. But inland metro Atlanta's 115-120 mph designation still carries significant material and installation requirements that many contractors ignore or misunderstand.

The Georgia Department of Community Affairs (DCA) enforces these standards statewide. Local jurisdictions in Fulton County, Gwinnett County, DeKalb County, and Cobb County can add requirements but cannot reduce the state baseline. When your building inspector reviews a roof replacement permit, wind speed zone compliance sits at the top of the checklist.

Wind Speed Zones for Metro Atlanta Cities

Every city in the 1 Source Roofing service area falls within the 115-120 mph ultimate design wind speed zone. Here is the breakdown by community:

Exposure Category B applies to most suburban Atlanta neighborhoods with trees and adjacent structures that break wind flow. Homes on hilltops, lake frontage, or large cleared lots may fall into Exposure Category C, which increases the effective wind pressure on the roof and can require upgraded attachment methods.

How Wind Speed Zones Affect Your Roof

Wind speed zone classification drives three critical decisions during any roof replacement: material selection, fastener patterns, and underlayment attachment.

Material selection. The IRC requires shingles tested and rated for the design wind speed at your location. In Atlanta's 115 mph zone, three-tab shingles rated to only 60 mph (ASTM D3161 Class A) fail code. Your contractor must select shingles with wind ratings that meet or exceed the local requirement. Architectural (laminate) shingles from GAF, CertainTeed, and Owens Corning all offer product lines rated to 130 mph or higher.

Fastener patterns. The number of nails per shingle changes based on wind zone. Standard installations in lower-wind areas use four nails per shingle. In Atlanta's 115-120 mph zone, manufacturers require six nails per shingle to activate their highest wind warranty coverage. This applies to the field shingles, starters, and hip and ridge caps.

Underlayment attachment. Synthetic underlayment in high-wind areas requires closer fastener spacing than standard installations. The IRC specifies cap nail spacing of 6 inches on center at laps and 12 inches on center in the field for areas with design wind speeds above 110 mph. Self-adhered (peel-and-stick) underlayment eliminates this concern because it bonds to the roof deck without relying on mechanical fasteners.

"Wind code compliance is a warranty issue, an insurance issue, and an inspection issue. Skip the six-nail pattern in Atlanta's wind zone, and you risk all three."

The IRC also addresses edge metal (drip edge) wind resistance. Section R905.2.8.5 requires drip edge installed at eaves and rakes, with fastener spacing of 12 inches on center. In areas with design wind speeds above 110 mph, that spacing tightens. Your contractor must verify the specific spacing requirement for your jurisdiction.

Shingle Wind Ratings and ASTM Standards

Two ASTM test methods govern shingle wind resistance. Understanding the difference matters because contractors and insurance adjusters reference these ratings in documentation, claims, and permit applications.

ASTM D3161: Fan-Induced Wind Resistance

This older test subjects shingle tabs to forced air at controlled speeds. Shingles receive one of three classifications:

• Class A: Resists 60 mph wind
• Class F: Resists 110 mph wind
• Class H: No established threshold under D3161 (this designation belongs to D7158)

D3161 tests wind resistance through tab lifting. The test has limitations because it measures wind blowing across the surface without accounting for uplift pressure beneath the shingle.

ASTM D7158: Uplift Force Resistance

This newer, more rigorous test measures the actual uplift force shingles withstand before failure. Classifications under D7158:

• Class D: Resists wind speeds up to 90 mph
• Class G: Resists wind speeds up to 120 mph
• Class H: Resists wind speeds up to 150 mph

For metro Atlanta's 115 mph zone, shingles must carry a minimum ASTM D7158 Class G rating. Class H provides an additional safety margin. GAF Timberline HDZ shingles, which 1 Source Roofing installs as a standard product, carry D7158 Class H (150 mph) and D3161 Class F (110 mph) ratings.

When reviewing a roofing proposal, ask your contractor which ASTM ratings the proposed shingle carries. If the answer does not include D7158 Class G or H, the product may not meet code for your location. Check the manufacturer's product data sheet for confirmation.

Fastener Patterns in High-Wind Zones

Nail placement determines whether a shingle survives an Atlanta thunderstorm or ends up in your neighbor's yard. The IRC and manufacturer specifications both address fastener count and placement, and they must agree for warranty and code compliance.

Four Nails vs. Six Nails

Standard shingle application calls for four nails per shingle, placed in the manufacturer's designated nailing zone. In wind zones with design speeds above 110 mph, the code and every major manufacturer require six nails per shingle. Metro Atlanta's 115 mph zone triggers this six-nail requirement across all jurisdictions.

The two additional nails go at the outer edges of the nailing zone, about one inch from each end of the shingle. This pattern prevents wind from catching the shingle edges and peeling them upward. Studies by the Insurance Institute for Business and Home Safety (IBHS) found that six-nail patterns reduce shingle blow-off by over 50% compared to four-nail installations in the same wind conditions.

Hand-Nailing vs. Pneumatic Nailers

Both methods can produce code-compliant installations. The risk with pneumatic nailers is over-driving. An over-driven nail breaks through the fiberglass mat, reducing holding power to near zero. Under-driven nails sit proud of the surface and prevent the shingle above from sealing properly.

1 Source Roofing crews calibrate pneumatic nailers at the start of each project and re-check throughout the day as temperature and humidity change. Building inspectors in Gwinnett, Fulton, and Cobb counties flag over-driven and under-driven nails as code violations. A failed inspection means the crew must pull affected shingles, add new ones, and re-nail.

Starter Strip Fastening

Starter shingles along eaves and rakes require their own fastener pattern. In high-wind zones, manufacturers specify nails at 12-inch intervals along the starter strip, placed low enough to be covered by the first course of field shingles. The adhesive strip on the starter bonds to the first course above, creating a sealed edge that resists wind uplift at the roof perimeter where wind forces concentrate.

Hip and Ridge Cap Wind Requirements

Hip and ridge caps sit at the highest points of your roof. Wind speeds increase with elevation, and these components face more wind exposure than field shingles on the slopes below. Yet many contractors treat ridge caps as an afterthought, using hand-cut field shingles instead of purpose-built hip and ridge products.

The IRC requires hip and ridge shingles to meet the same wind resistance standards as field shingles. Manufacturers go further. GAF requires their proprietary TimberTex or Seal-A-Ridge products installed with two nails per cap shingle in standard zones and two nails at specific placements in high-wind zones. CertainTeed specifies similar requirements for their Shadow Ridge line.

Factory-made hip and ridge cap shingles contain pre-applied adhesive strips sized for cap application. Hand-cut three-tab shingles lack these adhesive strips and have thinner profiles. In Atlanta's wind zone, hand-cut ridge caps create a weak point that wind exploits during severe storms. Insurance adjusters recognize this failure pattern and may attribute the damage to improper installation rather than the storm itself.

Key ridge cap requirements in the 115-120 mph zone:

• Use manufacturer-specified hip and ridge products
• Follow the manufacturer's nail count and placement diagram
• Apply a bead of roofing cement under each cap in enhanced wind zones if required by the manufacturer
• Maintain proper overlap (exposure) per manufacturer instructions, which varies by product line

1 Source Roofing uses factory-made hip and ridge products on every installation. The cost difference between hand-cut caps and purpose-built products is small. The performance difference during a 70 mph straight-line wind event is substantial.

Storm Damage and Code Compliance

Atlanta's wind events hit hard. Severe thunderstorms produce straight-line winds between 60 and 100 mph. Tornadoes, though less frequent, strike metro Atlanta with EF0 to EF2 intensity (65 to 135 mph). The March 2021 tornado outbreak damaged hundreds of roofs across Coweta, Fulton, and DeKalb counties. In each case, replacement roofs had to meet current wind speed code requirements.

Georgia's building code contains a code upgrade provision. When storm damage requires replacement of your roof, the new installation must comply with the code edition in effect at the time of replacement. A home built in 1998 under older wind maps now sits in a zone with higher design wind speeds. The new roof must hit those higher numbers.

This matters for your insurance claim. Georgia law (O.C.G.A. 33-24-46) requires insurers to pay the cost of bringing damaged portions of a home up to current building code when the policyholder carries replacement cost coverage. Your contractor must document the specific code requirements that apply to your replacement and include them in the insurance claim scope.

Common code upgrade items covered by insurance when documented:

• Upgraded shingle wind rating (from Class D to Class G or H)
• Six-nail pattern where four nails were used on the original installation
• Synthetic underlayment replacing deteriorated felt paper
• Ice and water shield in valleys and at eaves per current requirements
• Drip edge at eaves and rakes (many older homes lack drip edge)

A contractor who fails to document these code upgrades leaves money on the table. The homeowner pays the difference out of pocket, or the new roof gets installed below current code. Both outcomes are unacceptable. Read more about insurance vs. out-of-pocket replacement costs and how denied claims in Georgia can be challenged.

"Every storm damage claim should include current code requirements. Georgia law supports the homeowner's right to a code-compliant replacement. The contractor who skips this step costs you thousands."

1 Source Installs for Atlanta's Wind Conditions

1 Source Roofing and Restoration exceeds Georgia's wind speed code minimums on every residential installation in metro Atlanta. Code sets a floor. We build above it.

GAF Timberline HDZ with LayerLock Technology. This shingle carries a 130 mph limited wind warranty when installed per GAF specifications. The ASTM D7158 Class H rating covers 150 mph uplift resistance. Atlanta's 115 mph code requirement falls well within the product's tested performance range. Learn more about GAF roofing systems.

Six-nail patterns on every shingle. No exceptions. Our crews nail six per shingle in the manufacturer-designated nailing zone. We verify placement throughout installation and before the final walkthrough.

Factory ridge caps, not hand-cut. GAF TimberTex or Seal-A-Ridge products on every hip and ridge line. Proper adhesive coverage. Proper nail count.

Starter strip at eaves and rakes. We install GAF Pro-Start or WeatherBlocker starter strips along every eave and rake edge with 12-inch nail spacing. The adhesive bond between starter and first course seals the most vulnerable roof perimeter.

Documentation for permits and insurance. We pull permits, specify wind-rated materials on the scope of work, and photograph fastener patterns during installation. This documentation supports your permit inspection, manufacturer warranty registration, and any future insurance claim.

Cities across our service area trust 1 Source Roofing to meet and exceed wind code requirements:

• Storm damage restoration in Alpharetta
• Roof replacement in Buckhead
• Roof replacement in Sandy Springs
• Storm damage restoration in Johns Creek
• Roof replacement in Marietta
• Roof replacement in Roswell

For detailed information on Georgia's residential roofing code framework, visit our Georgia Residential Roofing Code Guide. For roof slope and ventilation requirements that interact with wind code, see our pages on minimum roof slope and ventilation requirements.