When homeowners search for "galvanized metal roofing" or "galvanized steel roofing," they're usually looking for the most affordable path to a metal roof. And galvanized steel is indeed the entry-level option for metal roofing, with corrugated panels starting as low as $4 to $5 per square foot installed. But in coastal Florida, there's a critical distinction that can mean the difference between a 30-year roof and a 10-year roof: galvanized versus Galvalume.
Pinellas County sits on a peninsula bordered by the Gulf of Mexico to the west and Tampa Bay to the east. Salt air reaches every corner of the county. Even homes in Largo or Pinellas Park, 5+ miles from the nearest shoreline, experience enough salt exposure to affect the performance of standard galvanized coatings over time. For waterfront communities like Clearwater Beach, Indian Rocks Beach, St. Pete Beach, and Treasure Island, the salt environment is aggressive enough to destroy unprotected metal roofing within a decade.
This guide explains the chemistry behind galvanized and Galvalume coatings, compares their performance in Florida conditions, covers the panel profiles available, breaks down costs, and helps you choose the right metal roofing system for your specific Pinellas County location.
Galvanized Steel Roofing: What It Is and How It Works
Galvanized steel roofing is steel sheet that has been coated with a layer of zinc through a hot-dip galvanizing process. The steel sheet passes through a bath of molten zinc at approximately 860°F, and the zinc bonds metallurgically to the steel surface. The result is a corrosion-resistant coating that protects the underlying steel from rust and oxidation.
Galvanized Coating Weights
The thickness of the zinc coating determines how long the protection lasts. Coating weight is measured in ounces of zinc per square foot of total surface area (both sides combined):
| Coating Designation | Zinc Weight (oz/sq ft) | Zinc Thickness (per side) | Typical Use |
|---|---|---|---|
| G-40 | 0.40 | ~0.35 mil | Interior, dry environments only |
| G-60 | 0.60 | ~0.50 mil | Budget agricultural panels |
| G-90 | 0.90 | ~0.75 mil | Standard roofing and siding |
| G-115 | 1.15 | ~0.95 mil | Premium roofing, moderate exposure |
For roofing applications in Florida, G-90 is the minimum acceptable coating weight. G-60 panels sold at agricultural supply stores may be tempting at $2 to $3 per linear foot, but they corrode much faster in our salt air environment and should be avoided for any structure you want to protect long-term.
How Zinc Protection Works
Zinc protects steel through two mechanisms. First, it forms a physical barrier between the steel and the atmosphere. Second, and more importantly, zinc provides cathodic (sacrificial) protection. If the coating is scratched or damaged, exposing the steel underneath, the surrounding zinc corrodes preferentially, protecting the exposed steel from rust. This self-healing property is what makes galvanized coatings effective.
The limitation is that the zinc is gradually consumed over time. In a dry inland environment, G-90 zinc can last 50+ years before significant depletion. But in Florida's humid, salt-laden coastal air, the zinc corrodes much faster. White rust (zinc hydroxide) forms on the surface as the zinc reacts with moisture and salt. Once the zinc layer is depleted, the exposed steel rusts rapidly.
Galvalume Metal Roofing: The Florida-Friendly Alternative
Galvalume was developed by Bethlehem Steel Corporation in 1972 as an improvement over standard galvanized coatings for applications requiring superior corrosion resistance. The coating consists of 55% aluminum, 43.4% zinc, and 1.6% silicon by weight. This specific ratio was determined through extensive testing to provide the optimal balance of barrier protection (from the aluminum) and cathodic protection (from the zinc).
Why Galvalume Outperforms Galvanized in Florida
The aluminum component in Galvalume is what makes the difference in coastal environments. Aluminum forms a dense, self-healing oxide layer (aluminum oxide) that is highly resistant to salt air corrosion. This oxide layer acts as a barrier that dramatically slows the rate of coating consumption compared to pure zinc.
| Property | Galvanized (G-90) | Galvalume (AZ-55) |
|---|---|---|
| Coating composition | 100% zinc | 55% aluminum, 43.4% zinc, 1.6% silicon |
| Barrier protection | Moderate | Excellent (aluminum oxide layer) |
| Cathodic protection | Excellent | Good (zinc component) |
| Cut-edge protection | Good (zinc migrates to edges) | Moderate (less zinc to migrate) |
| Salt air resistance | Fair (white rust develops) | Very good (aluminum oxide resists salt) |
| Heat reflectivity | Moderate | High (aluminum is more reflective) |
| FL coastal lifespan (unpainted) | 8-20 years | 25-40 years |
| FL inland lifespan (unpainted) | 20-30 years | 40-60 years |
| Cost premium over galvanized | Baseline | +10-20% |
Bethlehem Steel's original field test panels installed in 1972 have been monitored continuously. After 50+ years, Galvalume panels in moderate marine environments still show serviceable coating integrity. Galvanized panels from the same test batch experienced complete zinc depletion and active steel corrosion within 15 to 25 years in the same locations.
Galvalume Coating Chemistry Explained
Understanding the coating structure helps explain why the 55/43.4/1.6 ratio was selected. The aluminum forms a continuous dendritic (tree-like) matrix throughout the coating, with zinc filling the spaces between the aluminum dendrites. The silicon is added to promote bonding between the coating and the steel substrate.
When the coating is exposed to the atmosphere, the aluminum phase forms a protective aluminum oxide layer that is extremely thin but highly effective at blocking further corrosion. The zinc phase provides cathodic protection at scratches and cut edges, though with less zinc mass than a fully galvanized coating, this cathodic protection is more limited in scope. This is why painted Galvalume roofing (with edge protection from paint) performs even better than bare Galvalume in coastal applications.
Galvanized vs. Galvalume: When to Use Each in Pinellas County
The decision between galvanized and Galvalume roofing in Pinellas County depends primarily on your property's proximity to saltwater and the importance of the structure:
When Standard Galvanized Is Acceptable
- Agricultural buildings: Barns, equipment sheds, and pole buildings in inland areas where the structure's expected useful life doesn't exceed 20 years and budget is the primary constraint.
- Temporary or semi-permanent structures: Covered storage areas, seasonal market canopies, and structures where replacement in 10 to 15 years is an acceptable plan.
- Inland budget projects: Properties in eastern Pinellas County (Oldsmar, East Lake, Palm Harbor inland) that are more than 5 miles from saltwater, where the galvanized coating will last longer.
- Interior or sheltered applications: Covered breezeway ceilings, under-deck roofing, or applications protected from direct rain and salt spray.
When Galvalume Is Required
- Any primary residence: Your home deserves the longer-lasting coating. The 10-20% cost premium for Galvalume pays for itself many times over through extended lifespan.
- Commercial buildings: Business properties where roof failure creates liability, business interruption, and costly emergency repairs.
- Properties within 3 miles of saltwater: This includes the vast majority of Pinellas County. At this distance, salt air is aggressive enough to significantly shorten galvanized coating life.
- Barrier island and waterfront properties: Clearwater Beach, Indian Rocks Beach, Madeira Beach, St. Pete Beach, Treasure Island, and similar locations. In these environments, even Galvalume should be paired with a premium paint system (Kynar/PVDF) for maximum protection.
- Any roof where 30+ year lifespan is expected: If you're investing in a metal roof to avoid future replacements, Galvalume is the minimum coating specification.
The "Galvanized Tin Roof" Confusion
Many homeowners search for "galvanized tin roof" when shopping for metal roofing. It's worth clearing up this terminology because no modern roofing panel is made from tin. The term persists from the early 1900s when tin-plated steel was common for roofing. Today's "tin roof" is actually galvanized steel or Galvalume steel.
If you're looking for that classic corrugated "tin roof" appearance, you're shopping for galvanized or Galvalume corrugated steel panels. The familiar wavy profile is still available and remains one of the most affordable metal roofing options. Just make sure you're getting the right coating for your Florida location, and be aware that the charming "weathered tin" look that some homeowners admire is actually active corrosion. An intentionally weathered or aged appearance should come from architectural paint finishes, not coating failure.
Panel Profiles: Corrugated vs. Standing Seam
Both galvanized and Galvalume steel are available in multiple panel profiles. The two most common for residential and commercial roofing are corrugated (exposed fastener) and standing seam (concealed fastener):
Galvanized Corrugated Metal Roofing
Corrugated panels feature a repeating wave or rib pattern and are attached with fasteners driven through the panel face into the structure below. This is the classic "tin roof" profile and remains the most affordable metal roofing option.
- Cost: $4.00-8.00 per square foot installed
- Pros: Lowest cost, fastest installation, readily available, easy to repair individual panels
- Cons: Exposed fasteners require maintenance (rubber washers degrade over time), limited color options in bare galvanized, lower wind ratings than standing seam
- Best for: Budget residential, agricultural, sheds, carports, and properties where cost is the primary driver
For a detailed look at corrugated metal roofing options and performance in Florida, see our corrugated metal roofing guide.
Standing Seam Metal Roofing
Standing seam panels interlock along raised seams and are attached with concealed clips that allow the panels to expand and contract with temperature changes. No fasteners penetrate the panel face, eliminating the maintenance issues associated with exposed fastener systems.
- Cost: $8.00-14.00 per square foot installed
- Pros: No exposed fasteners to maintain, superior wind uplift resistance, thermal expansion accommodation, premium appearance, longest lifespan
- Cons: Higher cost, requires skilled installation, longer installation time
- Best for: Primary residences, high-end commercial, coastal properties, any building where maximum performance and longevity justify the premium
Our standing seam metal roof guide covers this profile in detail, including the specific benefits for Florida's high-wind environment.
Panel Profile Comparison
| Feature | Corrugated (Exposed Fastener) | Standing Seam (Concealed Fastener) |
|---|---|---|
| Installed cost/sq ft | $4.00-8.00 | $8.00-14.00 |
| Wind rating | 110-150 mph (with proper fastening) | 140-180 mph |
| Fastener maintenance | Required (every 5-10 years) | Not required |
| Thermal movement | Restricted (fastener holes elongate) | Accommodated (floating clips) |
| Leak resistance | Good (depends on fastener integrity) | Excellent (no panel penetrations) |
| Lifespan (Galvalume, FL) | 25-40 years | 40-60 years |
| Appearance | Rustic/agricultural | Clean/modern/architectural |
| DIY friendly | Somewhat (small structures) | No (requires specialized tools) |
Galvanized Metal Roofing Cost: Complete Breakdown
Here's a detailed cost breakdown for galvanized and Galvalume metal roofing in the Pinellas County market in 2026:
| System | Coating | Cost/Sq Ft Installed | 2,000 Sq Ft Roof | FL Lifespan |
|---|---|---|---|---|
| Corrugated (26 ga) | Galvanized G-90 | $4.00-6.00 | $8,000-12,000 | 15-25 years |
| Corrugated (26 ga) | Galvalume AZ-55 | $4.50-7.00 | $9,000-14,000 | 25-40 years |
| Corrugated (24 ga) | Galvalume + SMP paint | $5.50-8.00 | $11,000-16,000 | 30-45 years |
| Corrugated (24 ga) | Galvalume + PVDF paint | $6.50-9.00 | $13,000-18,000 | 35-50 years |
| Standing seam (24 ga) | Galvalume AZ-55 | $8.00-11.00 | $16,000-22,000 | 40-55 years |
| Standing seam (24 ga) | Galvalume + PVDF paint | $9.00-14.00 | $18,000-28,000 | 45-60+ years |
For a comprehensive cost comparison including all metal roofing options, see our metal roof cost guide.
Paint Systems: SMP vs. PVDF (Kynar)
Most galvanized and Galvalume roofing panels are available with factory-applied paint finishes. The paint system affects both appearance and longevity:
- SMP (Silicone Modified Polyester): The standard paint finish for metal roofing. SMP paints offer good color retention and UV resistance at a moderate cost. They typically maintain acceptable appearance for 15 to 25 years in Florida before noticeable fading occurs.
- PVDF (Kynar/Hylar): The premium paint finish. PVDF paints use a fluoropolymer resin (polyvinylidene fluoride) that provides exceptional UV resistance, color retention, and chemical resistance. In Florida's intense sun, PVDF-coated panels maintain their color and gloss for 30 to 40+ years. The coating also provides an additional barrier against salt air corrosion.
For coastal Pinellas County properties, PVDF paint over Galvalume substrate is the recommended specification. The combination of Galvalume's superior base corrosion resistance and PVDF's UV and chemical protection creates a roofing panel that can last 50+ years with minimal maintenance.
Florida Building Code Compliance
All metal roofing installed in Pinellas County must comply with the Florida Building Code requirements for wind resistance, fire rating, and structural loading. Here are the key code considerations for galvanized and Galvalume metal roofing:
Wind Uplift Requirements
Most of Pinellas County falls within wind zones requiring roofing systems rated for 150 to 170 mph ultimate design wind speeds. Metal roofing systems achieve these ratings through a combination of panel gauge, profile geometry, and fastener/clip spacing. Thinner gauge panels (29 or 26 gauge) with exposed fasteners may not achieve the required ratings in all locations without very tight fastener spacing. Heavier gauge panels (24 gauge) with standing seam profiles and engineered clip spacing more easily meet the requirements.
Florida Product Approval
All roofing products installed in Florida must carry a valid Florida Product Approval (FPA) or Miami-Dade Notice of Acceptance (NOA). The product approval documents the tested wind resistance, fire rating, and other performance characteristics. When purchasing galvanized or Galvalume panels, verify that the specific product carries a current FPA number. Generic agricultural panels from out-of-state suppliers may not have Florida Product Approval and cannot be legally installed for permitted work in Pinellas County.
Minimum Gauge for Roofing
While the Florida Building Code doesn't specify a minimum gauge for all metal roofing, the practical requirements for wind resistance mean that:
- 29 gauge: Generally too light for Florida roofing. Limited to sheltered applications and small non-permit structures.
- 26 gauge: Acceptable for corrugated and R-panel profiles on residential structures with proper fastener spacing. Common for budget installations.
- 24 gauge: The standard for quality residential and commercial metal roofing in Florida. Provides adequate structural strength for standing seam clips and resists denting from foot traffic and debris.
- 22 gauge: Premium specification for coastal commercial and institutional buildings. Maximum strength and dent resistance.
Maintaining Galvanized and Galvalume Roofing in Coastal Florida
Metal roofing is often described as "maintenance-free," but that's not entirely accurate in a coastal salt air environment. Here's what maintenance looks like for each coating type in Pinellas County:
Galvanized Steel Maintenance
- Annual rinse: Use a garden hose to rinse salt deposits from the roof surface at least twice per year (more frequently for coastal properties). Salt accumulation accelerates zinc depletion.
- Inspect for white rust: White powdery deposits on bare galvanized surfaces indicate zinc corrosion. If white rust appears, the coating is being consumed. Consider applying a zinc-rich paint to extend the protection.
- Fastener inspection: For exposed fastener systems, check all fasteners annually for loose screws and degraded rubber washers. Replace washers or entire fasteners as needed.
- Touch-up scratches promptly: Any scratch that exposes bare steel should be touched up with cold galvanizing compound or zinc-rich paint immediately.
Galvalume Maintenance
- Semi-annual rinse: Rinse the roof surface with a garden hose twice per year to remove salt and debris. Galvalume is more salt-resistant than galvanized, but regular rinsing extends the coating life.
- Clean debris from seams and valleys: Leaf litter and debris that trap moisture against the panel surface can cause localized corrosion, even on Galvalume. Keep valleys, gutters, and seam areas clear.
- Inspect paint (if painted): For SMP or PVDF painted panels, look for paint chalking, fading, or peeling during annual inspections. Well-maintained paint extends the coating life significantly.
- Fastener maintenance (exposed systems): Same as galvanized. Exposed fastener systems require periodic washer replacement regardless of coating type.
Galvanized vs. Galvalume vs. Other Metal Roofing Options
Galvanized and Galvalume are the two most common steel coating options, but they're not the only metal roofing materials available. Here's how they compare to the full range of options for Pinellas County:
| Material | Salt Air Resistance | Cost/Sq Ft | FL Lifespan | Best Application |
|---|---|---|---|---|
| Galvanized steel (G-90) | Fair | $4.00-8.00 | 15-25 years (coastal) | Inland agricultural, budget |
| Galvalume steel (AZ-55) | Very good | $4.50-14.00 | 30-55 years | Residential, commercial |
| Galvalume + PVDF paint | Excellent | $6.50-14.00 | 40-60+ years | Coastal residential, premium |
| Aluminum (mill finish) | Excellent | $7.00-16.00 | 40-60 years | Direct waterfront, salt zones |
| Copper | Superior | $18.00-30.00 | 75-100+ years | Architectural, historic |
| Zinc | Excellent | $15.00-25.00 | 60-100 years | Architectural, low maintenance |
For a comprehensive comparison of all steel roofing options available for your property, our steel roofing guide covers every coating, gauge, and profile combination.
Choosing the Right Metal Roof for Your Pinellas County Property
Here's our straightforward recommendation based on property type and location:
- Waterfront/barrier island home: 24-gauge Galvalume standing seam with PVDF paint and stainless steel clips. This is the premium specification for maximum corrosion resistance and longevity. Consider aluminum panels for properties within 1,500 feet of saltwater.
- Residential (within 3 miles of coast): 24-gauge Galvalume with PVDF or high-quality SMP paint. Standing seam preferred. Corrugated with Galvalume and PVDF is an acceptable budget option.
- Residential (inland Pinellas): 24 or 26-gauge Galvalume with SMP paint. Standing seam or corrugated based on budget and aesthetics.
- Commercial/industrial: 24-gauge Galvalume standing seam with PVDF for premium projects. 24-gauge Galvalume R-Panel for budget commercial.
- Agricultural/storage: 26-gauge galvanized corrugated is acceptable for budget applications where 15 to 20 year lifespan is adequate.
No matter which specification you choose, make sure the product carries a valid Florida Product Approval and that your contractor designs the installation to meet the Florida Building Code wind requirements for your specific location. The difference between a metal roof that survives 30+ years and one that fails prematurely almost always comes down to the coating selection and installation quality.
Frequently Asked Questions About Galvanized and Galvalume Metal Roofing
What is the difference between galvanized and Galvalume metal roofing?
Galvanized steel roofing is coated with a layer of zinc (typically G-90 at 0.90 ounces of zinc per square foot). Galvalume metal roofing is coated with a blend of 55% aluminum, 43.4% zinc, and 1.6% silicon. The aluminum in Galvalume provides superior corrosion resistance and better performance in salt air environments, while galvanized relies entirely on zinc for protection. Galvalume lasts 2 to 3 times longer than galvanized in coastal Florida conditions.
How long does galvanized steel roofing last in Florida?
Galvanized steel roofing lifespan in Florida depends on location. Inland properties more than 5 miles from saltwater can expect 20 to 30 years from standard G-90 galvanized panels. Properties within 1 to 5 miles of the coast may see 10 to 20 years. Coastal properties within 1 mile of saltwater should expect only 8 to 15 years from galvanized steel before significant corrosion develops. For coastal locations, Galvalume is the better choice.
Is galvanized steel roofing good for Florida salt air?
Standard galvanized steel roofing is not ideal for Florida salt air environments. The zinc coating corrodes when exposed to salt spray, and coastal Pinellas County properties can see white rust developing within 3 to 5 years. For properties within 3 miles of saltwater, Galvalume-coated steel or aluminum panels with PVDF paint are recommended. For properties within 1,500 feet of saltwater, aluminum or stainless steel clips and fasteners should also be used.
What is a galvanized tin roof?
The term "galvanized tin roof" is a common but technically inaccurate name for galvanized steel roofing. Modern metal roofing panels are made from steel coated with zinc (galvanized) or aluminum-zinc alloy (Galvalume), not tin. The name persists from the early 1900s when tin-plated steel was used for roofing. If you are shopping for a "tin roof" today, you are actually looking for galvanized steel or Galvalume steel roofing panels.
How much does galvanized metal roofing cost in Florida?
Galvanized metal roofing costs $4.00 to $8.00 per square foot installed for corrugated panels and $8.00 to $14.00 per square foot for standing seam profiles in Pinellas County in 2026. Galvalume-coated panels add $0.50 to $1.50 per square foot over standard galvanized. Premium paint finishes (Kynar/PVDF) add another $1.00 to $2.00 per square foot. A complete 2,000-square-foot galvanized corrugated roof runs $8,000 to $16,000 installed.
Does galvanized corrugated metal roofing meet Florida building code?
Yes, galvanized corrugated metal roofing can meet Florida Building Code requirements when properly engineered and installed. The product must carry a valid Florida Product Approval or Miami-Dade NOA, and the installation must be designed to meet the wind uplift requirements for the specific building location. Most of Pinellas County requires systems rated for 150 to 170 mph ultimate design wind speeds. Fastener type, spacing, and panel gauge all affect code compliance.
What is Galvalume and why is it better for Florida roofing?
Galvalume is a coating for steel roofing panels made from 55% aluminum, 43.4% zinc, and 1.6% silicon by weight. It was developed by Bethlehem Steel in the 1970s and is now manufactured under license by multiple companies. Galvalume outperforms standard galvanized coatings in Florida because the aluminum component creates a durable oxide barrier that resists salt air corrosion. In field studies, Galvalume panels last 2 to 3 times longer than equivalent galvanized panels in coastal environments.
Should I use galvanized or Galvalume roofing in Pinellas County?
For most residential and commercial roofing projects in Pinellas County, Galvalume is the recommended choice. Pinellas County is a coastal peninsula surrounded by Tampa Bay and the Gulf of Mexico, so even inland properties experience some salt air exposure. Galvanized steel is acceptable for agricultural buildings, storage structures, and projects more than 5 miles from saltwater where maximum budget savings is the priority. For any primary residence or commercial building, Galvalume provides significantly better long-term value.
Get a Metal Roofing Quote for Your Pinellas County Property
Choosing between galvanized and Galvalume is one of the most important decisions you'll make when investing in a metal roof for your Florida property. The right coating selection, combined with the appropriate panel profile and paint system, determines whether your metal roof lasts 15 years or 60+ years. In coastal Pinellas County, that distinction is worth getting right.
Our team installs both corrugated and standing seam metal roofing systems throughout Pinellas County. We work with all major metal roofing manufacturers and understand the specific coating, gauge, and fastener requirements for every location in our service area, from waterfront homes in Dunedin to commercial buildings in St. Petersburg.
Contact us for a free metal roofing estimate. We'll evaluate your property's salt air exposure, discuss your priorities, and provide a detailed proposal with the right specification for your location and budget. No generic quotes, just recommendations tailored to your specific Pinellas County property.