Metal Roofing Code in Georgia

Two IRC Sections, Two Metal Roof Categories: R905.4 and R905.10

Georgia's building code splits metal roofing into two categories, each governed by its own IRC section. Understanding which section applies to your project determines the slope minimum, attachment method, and testing standards your contractor must follow.

IRC R905.4 covers metal roof shingles. These are individual panels stamped to resemble traditional shingles, slate, or tile. They interlock at the edges and attach to the roof deck through concealed or exposed fasteners. The code requires metal shingles to comply with UL 580 wind uplift classification and meet the manufacturer's published installation specifications.

IRC R905.10 covers metal roof panels. This category includes standing seam systems, corrugated panels, and structural metal panels. These products span larger areas than shingles and attach through clips, through-fasteners, or a combination. R905.10 references ASTM E1592 for structural performance and UL 580 for wind uplift classification.

The distinction matters for your project's permit application. A building inspector in Fulton County or Gwinnett County will verify that the installed system matches the code section cited on the permit. Installing a standing seam system under an R905.4 permit creates a compliance conflict that triggers re-inspection and potential correction orders.

1 Source Roofing and Restoration holds GAF certification and CertainTeed certification, and our crews install both metal shingle and metal panel systems across metro Atlanta. We identify the correct code section during the proposal phase, pull the appropriate permit, and coordinate all inspections through project completion.

Minimum Slope: From 0.25:12 for Panels to 3:12 for Metal Shingles

Metal roofing offers the widest slope range of any roofing material permitted under Georgia code. That flexibility makes metal the go-to solution for complex roof geometries that combine steep pitches with low-slope transitions.

Metal shingles under IRC R905.4 require a minimum 3:12 slope. This matches the minimum for wood shingles and reflects the fact that metal shingles rely on overlapping edges to shed water. At slopes below 3:12, water moves too slowly across the panel surface and can wick under the interlocking joints.

Metal roof panels under IRC R905.10 allow far lower slopes. Standing seam panels with lapped, non-soldered seams (no sealant) can go as low as 0.25:12. That is one quarter inch of rise per foot of horizontal run. Panels with sealant at the laps permit slopes as low as 0.5:12. Panels with soldered seams have no minimum slope restriction.

For modern custom homes in Buckhead and Sandy Springs, architects often specify standing seam metal for low-slope roof sections that connect steep gable ends. The 0.25:12 minimum makes this possible without transitioning to a flat roof membrane system like modified bitumen. The result: one material system across the entire roof, with consistent aesthetics and a single warranty.

UL 580 and ASTM E1592: Wind Uplift Standards for Georgia Metal Roofs

Metro Atlanta sits in a wind zone where design speeds range from 115 to 130 mph under ASCE 7-16. Every metal roofing system installed in this zone must demonstrate resistance to the wind pressures those speeds generate. Two testing standards prove that resistance: UL 580 and ASTM E1592.

UL 580 classifies metal roofing into uplift resistance categories: UL 30, UL 60, and UL 90. Each number represents the sustained negative pressure (in pounds per square foot) the system withstood during testing. UL 90 is the standard specification for commercial and premium residential installations in Georgia. A UL 90 rated system resisted 90 psf of uplift pressure in a controlled laboratory test without panel separation, seam failure, or clip disengagement.

ASTM E1592 tests structural performance of metal roof panel systems under uniform static air pressure. The test applies positive and negative pressures to a full-size panel assembly and measures deflection, fastener withdrawal, and seam integrity. The test report documents the maximum pressure the system withstood before failure. Your contractor compares this rated pressure against the calculated design pressure for your specific building to confirm adequacy.

Wind pressure varies across the roof surface. Corners experience the highest uplift. Perimeter zones rank second. The field (center) area sees the lowest pressures. ASCE 7-16 divides the roof into these three zones and assigns different design pressures to each. Your metal roofing system must meet the pressure requirement for each zone. In practice, this means tighter clip spacing at corners and perimeters than in the field. A system that passes UL 90 in the field may need UL 120 equivalent performance at corners.

For homes in Alpharetta and Johns Creek situated on elevated lots with open exposures, the calculated wind pressures increase. Trees, neighboring structures, and terrain features affect the exposure category. Hilltop homes with minimal surrounding obstructions fall into Exposure C or D, which produce higher design pressures than the Exposure B classification that applies to typical suburban settings.

Fastener Patterns and Thermal Expansion: The Details That Make or Break a Metal Roof

Metal roofing expands and contracts with temperature changes. A 20-foot standing seam panel in metro Atlanta can grow by 0.25 inches between a 30-degree winter morning and a 160-degree summer roof surface temperature. That 130-degree swing happens every year, and the fastening system must accommodate it without buckling panels, breaking seams, or loosening clips.

Standing seam systems handle thermal movement through floating clips. The panel locks into the clip at the seam, but the clip allows the panel to slide along its length as it expands and contracts. Fixed clips anchor the panel at one point (typically the ridge or eave), and all other clips float. This design keeps the seam locked tight against wind uplift while allowing the panel body to move with temperature.

Through-fastened metal panels (corrugated and R-panel systems) handle thermal movement less gracefully. The screws penetrate the panel face and lock it to the purlin or deck below. As the panel expands, the screw holes elongate, and the neoprene washers compress. Over 10 to 15 years, this repeated cycling loosens the fasteners and creates leak paths around each screw hole. For this reason, through-fastened systems are less common on premium residential installations in Roswell and Marietta.

Georgia code requires that metal roofing fasteners match the panel material's corrosion resistance. Stainless steel fasteners work with all metal roof types. Galvanized fasteners pair with galvanized steel panels. Aluminum rivets pair with aluminum panels. Mixing fastener and panel metals creates the galvanic corrosion problem discussed below.

Clip spacing follows the manufacturer's tested installation schedule, which the code incorporates by reference. Typical standing seam clip spacing runs 12 to 24 inches in the field area and 6 to 12 inches at perimeters and corners. Your contractor must follow the specific schedule for the product being installed. Wider spacing than specified voids the warranty and creates a code violation.

Dissimilar Metal Contact: The Corrosion Code You Cannot Ignore

The IRC prohibits direct contact between dissimilar metals in roofing assemblies. When two different metals touch in the presence of moisture, an electrochemical reaction called galvanic corrosion attacks the less noble (anodic) metal. Georgia's humid subtropical climate provides constant moisture, making this code requirement critical for every metal roof in the state.

The galvanic series ranks metals from most noble (cathodic) to least noble (anodic). Copper and stainless steel sit near the noble end. Aluminum falls in the middle. Galvanized steel and zinc sit toward the anodic end. When copper contacts aluminum, the aluminum corrodes at an accelerated rate. When aluminum contacts galvanized steel, the galvanized steel corrodes faster.

In practical roofing terms, this restriction affects several common details. Copper gutters installed on a steel or aluminum metal roof create galvanic corrosion at the contact point and wherever copper-laden runoff touches the metal panels below. Aluminum flashing fastened against a copper roof corrodes within 3 to 5 years. Stainless steel screws in aluminum panels create minimal galvanic potential and are generally acceptable, but zinc-plated screws in copper panels are not.

The code solution: use the same metal throughout the roof system, or install isolating barriers between dissimilar metals. Isolating barriers include neoprene washers, butyl tape, EPDM strips, or factory-applied coatings that prevent metal-to-metal contact. These barriers must remain intact for the life of the roof, so they must resist UV degradation, heat cycling, and compression.

For homeowners in Buckhead considering a copper standing seam roof with steel structural supports, your contractor must detail every connection point where dissimilar metals might touch. The proposal should specify the isolation method at each point and include the material specifications for the isolating barriers. This level of detail separates a professional installation from a future corrosion problem.

Panel Gauge, Coatings, and Material Standards for Georgia Metal Roofs

The IRC does not specify a universal minimum gauge for metal roofing. Instead, it references the manufacturer's tested assembly and requires that the installed system match the tested configuration. In practice, premium residential metal roofing in metro Atlanta uses 24-gauge or 26-gauge steel for standing seam panels. Thinner gauges (29-gauge) appear on agricultural buildings and outbuildings but lack the rigidity for residential installations subject to foot traffic during maintenance.

The gauge number works inversely: lower numbers mean thicker metal. A 24-gauge steel panel measures 0.0239 inches thick. A 26-gauge panel measures 0.0179 inches. That 0.006-inch difference translates to measurable increases in dent resistance, wind uplift performance, and panel flatness. For a premium home, 24-gauge is the standard specification.

Coatings determine the metal roof's lifespan and appearance retention. Galvalume (55% aluminum, 43.4% zinc, 1.6% silicon alloy coating) provides the base corrosion protection for most steel metal roofing. On top of the Galvalume base, manufacturers apply paint systems rated by their PVDF (polyvinylidene fluoride) resin content. Kynar 500 and Hylar 5000 are the two dominant PVDF resin brands. A full PVDF paint system with Kynar 500 or Hylar 5000 resists chalking, fading, and erosion for 30 to 40 years.

Galvanized steel (zinc-only coating) was the traditional standard but has largely given way to Galvalume for metal roofing. Galvalume outperforms galvanized steel in cut-edge corrosion resistance, which matters at every panel end, clip point, and penetration. Georgia's humidity and salt-influenced coastal air (which reaches inland during storm events) accelerate cut-edge corrosion on unprotected metal.

Aluminum panels use no protective coating on the base metal because aluminum forms its own oxide layer. Manufacturers paint aluminum panels for aesthetics, not corrosion protection. Aluminum weighs about one-third as much as steel, making it attractive for weight-sensitive applications. The tradeoff: aluminum costs more per square foot and dents more readily than steel of equivalent thickness.

Georgia Permit and Inspection Requirements for Metal Roofing

Every metal roof installation in Georgia requires a building permit. The permit application must specify the metal roof type (shingle or panel), the applicable IRC section (R905.4 or R905.10), the manufacturer and product name, the wind uplift rating, and the proposed attachment schedule. For new construction, the structural drawings must show the roof framing designed for the specific metal roofing system's load and attachment requirements.

For reroofing projects, Georgia code permits metal roofing installation over one layer of existing asphalt shingles in most cases, provided the existing deck structure is sound. The inspector verifies that the existing roof has been evaluated and that the new metal system's attachment reaches through to solid sheathing. Installing metal over multiple layers of existing roofing is not permitted.

Building inspectors in Fulton County, Gwinnett County, and Cobb County check several specific items during a metal roof inspection: clip or fastener spacing matches the approved plan, panel seam engagement is complete, flashing at penetrations and transitions meets IRC R903.2, drip edge and underlayment comply with their respective code sections, and the overall installation matches the manufacturer's published specifications.

1 Source Roofing and Restoration manages the complete permit and inspection process for every metal roofing project. We prepare the application with all required documentation, submit to the appropriate jurisdiction, schedule inspections at each milestone, and close the permit upon final approval. Homeowners in Alpharetta, Johns Creek, and Roswell receive a clean permit record that supports future property transactions and insurance claims.

Related Georgia Roofing Code Requirements