Install Galvalume Metal Roof

A galvalume metal roof is built from steel sheet coated with a precise blend of aluminum and zinc-typically 55% aluminum, 43.4% zinc, and 1.6% silicon-and that alloy gives you 2 to 4 times the rust resistance of plain galvanized steel in most inland and moderate-coastal environments. For Nassau County homes set back from the immediate ocean spray, a properly installed galvalume system offers the best balance of durability, cost, and low maintenance in metal roofing. For houses right on the water-think Oceanside beachfront or Atlantic Beach-aluminum or a painted galvalume upgrade may still be the smarter call.

I’m Chris Valenti. I’ve been installing metal roofs across Long Island for 17 years, with the last decade focused heavily on galvalume systems once I saw how they age compared to traditional galvanized or bargain uncoated steel. My shop in Mineola handles everything from standing seam on colonials to exposed-fastener panels on commercial garages, and I’ve learned exactly which galvalume profiles, coatings, and details survive our weather and salt air. This guide will walk you through what galvalume actually is, how it stacks up against alternatives, when it’s the right choice for your Nassau County property, and what an installation project looks like from planning to final trim.

What Is a Galvalume Metal Roof?

Galvalume Coating Basics

Galvalume is a steel roofing substrate coated at the mill with an aluminum-zinc alloy. That alloy combines the galvanic corrosion protection of zinc with the barrier and heat-reflective properties of aluminum. The result is a sheet that resists general atmospheric rust far better than traditional galvanized (zinc-only) steel. You’ll often see it called “AZ” coating on mill sheets-AZ50 or AZ55, with the number indicating coating weight. This coating is applied continuously during steel production, creating a smooth, metallurgical bond that won’t flake off like aftermarket paints can.

Bare galvalume has a distinctive dull silver-gray appearance and will naturally develop a patina over time as the aluminum oxidizes. That patina actually helps protect the underlying steel. Most residential and commercial projects, though, use painted galvalume-the galvalume substrate is factory-coated with high-performance paint, usually a PVDF resin like Kynar, which adds color, further corrosion resistance, UV protection, and a 25- to 40-year fade warranty depending on the manufacturer and color family.

Galvalume Panel Types and Profiles

• Standing seam panels: Typically 12-, 16-, or 18-inch-wide ribs with concealed clip fasteners. Made from galvalume coil with factory paint. Clean lines, minimal leaks, best for homes with any pitch above 3:12.
• Corrugated or ribbed exposed-fastener panels: Screws go through the panel into purlins or deck. Common on barns, workshops, sheds, and light commercial roofs. Less expensive than standing seam but requires more fastener maintenance over time.
• Metal shingles or tile profiles: Some systems stamp galvalume into shapes that mimic asphalt shingles or Spanish tile. These give you the galvalume substrate with a more traditional look, popular in HOA-controlled neighborhoods that resist visible seams.

Galvalume vs Other Metal Roofing Materials

Galvalume vs Galvanized Steel

Galvanized steel uses a pure zinc coating, applied hot-dip or electrolytically. It’s been the workhorse substrate for corrugated roofing for decades. The problem: zinc alone sacrifices itself quickly in wet, salty, or acidic environments, leading to red rust staining and eventual perforation. Galvalume’s aluminum component forms a tougher oxide barrier, slowing that process significantly. In Nassau County’s coastal-influenced atmosphere, galvanized roofs unpainted may show rust streaks in 8 to 12 years. A painted galvalume roof properly maintained can stay clean and intact for 30 to 50 years.

Edge corrosion-where panels are cut and raw steel is exposed-is also less aggressive on galvalume because the aluminum migrates slightly to cover the cut. You still should seal cut edges with touch-up paint or edge sealant, but galvalume gives you more forgiveness than galvanized if a contractor misses a spot.

Galvalume vs Aluminum

Aluminum roofing is the gold standard for coastal and high-salt environments because aluminum doesn’t rust-it forms a passive oxide that doesn’t stain or spread. If your house is within 500 feet of open saltwater with breaking waves, aluminum is usually my first recommendation. The tradeoffs: aluminum costs 40 to 60% more than painted galvalume, and it’s softer, so hail or foot traffic can dent panels more easily. Aluminum also has a higher coefficient of expansion, meaning you need careful clip and fastener design to allow movement without oil-canning.

Galvalume is a middle ground. It’s stronger and less expensive than aluminum, and in Nassau County locations more than half a mile inland-think Garden City, Westbury, Massapequa inland sections-it performs nearly as well as aluminum at a fraction of the cost. The key is distance from direct salt spray and proper detailing at seams and flashings.

Where Painted Galvalume Fits

Factory-applied paint systems on galvalume serve three purposes: they add a second layer of corrosion protection over the already-protective galvalume coating, they provide color and aesthetic options (everything from matte charcoal to bright reds), and they boost energy performance by reflecting solar heat. A light-colored PVDF finish can reflect 60 to 70% of solar energy, reducing attic temperatures and cooling loads in summer.

Paint also matters for warranty. Bare galvalume typically carries a 20- to 25-year perforation warranty. Add a premium PVDF topcoat, and you can get a combined 30- to 40-year paint and substrate warranty. For Nassau County homes, I almost always recommend painted galvalume over bare unless the client specifically wants the industrial look and understands the maintenance and appearance changes that come with natural patina.

Is Galvalume a Good Choice in Nassau County?

Distance from the Coast and Salt Exposure

Nassau County is unusual because you can be five miles from the ocean and still catch salt mist during nor’easters, or you can be two blocks from the water but buffered by dunes and other buildings. Galvalume manufacturers typically rate their product for “mild marine” or “moderate marine” environments-that means you’re near the coast but not in the direct salt-spray zone where waves break and mist lands on your roof daily.

In my experience, if you’re in towns like Levittown, Hicksville, Plainview, or the inland parts of Massapequa and Seaford, painted galvalume is an excellent choice. You get long-term corrosion resistance at a reasonable cost. If you’re on a waterfront street in Long Beach, Atlantic Beach, or Island Park, I’ll steer you toward aluminum or a very heavy paint system over galvalume with upgraded edge sealing and frequent inspections. A site visit and honest conversation about exposure always beats a one-size-fits-all material decision.

Wind and Storm Resilience

Galvalume is the substrate-wind performance comes from the panel profile, clip design, fastener spacing, and overall assembly. A standing seam galvalume roof with clips tested to 200 psf uplift will handle Nassau County’s coastal wind events as well as the same profile made from aluminum or galvanized steel. What matters is using tested assemblies, following manufacturer fastening schedules, and ensuring the deck and structure can transfer those loads.

One advantage of galvalume standing seam: the panels are typically 24- or 26-gauge steel, stiffer than equivalent aluminum, so they resist panel flutter and buckling under high wind or rapid pressure changes. In Superstorm Sandy aftermath work, I saw galvalume roofs lose ridge caps or trim pieces-fixable-but the field panels stayed locked down when installed correctly. Asphalt roofs next door were gone.

Aesthetic and Neighborhood Fit

Galvalume’s range of profiles and colors means it can match almost any architectural style. Bare galvalume has a modern, industrial vibe-great for contemporary builds or outbuildings but sometimes at odds with traditional colonials or Cape Cods. Painted galvalume in earthy tones-charcoal, forest green, terracotta, slate gray-blends beautifully with Long Island’s suburban character.

If you’re in an HOA community, check your covenants early. Some restrict metal roofs entirely; others allow them but specify “shingle-look” profiles or certain color palettes. I’ve had clients in Garden City Estates and parts of Manhasset required to use metal shingles rather than standing seam, and painted galvalume shingles meet that requirement while still delivering the substrate’s longevity.

Planning a Galvalume Metal Roof Installation

Evaluate the Existing Roof and Structure

Before I spec any galvalume system, I climb up and inspect what’s there. How many layers of shingles? Any sagging or soft spots in the deck? Signs of leaks, mold, or inadequate ventilation? Metal roofing is only as good as what it sits on. If your plywood deck is rotted or your rafters are undersized for snow and wind loads, we address that first.

Weight isn’t usually the issue-galvalume roofing typically weighs 1 to 1.5 pounds per square foot, far lighter than asphalt shingles. But if we’re adding furring or a vented air gap under the panels, or if we’re overlaying an existing metal roof, I verify the framing can handle the extra dead load and any changes to how wind uplift transfers through the assembly.

Select the Galvalume System Type

Your roof’s pitch, complexity, and visibility drive system choice. For steep-slope residential roofs-anything 4:12 and up-I usually recommend standing seam galvalume with concealed fasteners. It’s cleaner, more weather-tight, and easier to maintain. For low-slope commercial buildings, large garages, or agricultural structures where cost is paramount, exposed-fastener galvalume ribbed panels make sense; just plan for fastener inspections and possible replacements every 10 to 15 years.

Metal shingles or tile profiles are the aesthetic middle ground. They cost more than standing seam per square because they’re more labor-intensive to install, but they satisfy HOA rules and give you the galvalume substrate under a profile that doesn’t scream “metal roof” to the neighbors.

Confirm Local Code, Permits, and HOA Requirements

Nassau County requires building permits for most re-roofing projects, and the permit application will ask for details on materials, fastening, and sometimes energy compliance. Metal roofs must meet the same wind-uplift and fire-rating standards as any other roofing-typically Class A or B fire rating and tested assemblies rated for local design wind speeds, which range from 110 to 130 mph depending on your zone.

HOA approval can take as long as the permit process, sometimes longer. Submit panel samples, color chips, and manufacturer cut sheets early. If the HOA board meets monthly, plan for a two-month lead time before you can even order materials.

How a Galvalume Metal Roof Is Installed

1. Tear-Off or Preparation of the Old Roof

Most Nassau County residential projects involve a full tear-off of existing asphalt shingles down to the deck. We remove all layers, pull old nails, and inspect every sheet of plywood. Any spongy or delaminated sheets get replaced with new ½-inch or ⅝-inch CDX plywood, screwed down rather than nailed for better holding power. Debris goes into a dumpster or trailer the same day-no piles sitting on your lawn.

On some commercial or agricultural jobs, if there’s a single layer of sound existing metal and the deck underneath is solid, code and the galvalume panel manufacturer may allow an overlay. In that case, we still inspect for rust perforation, loose fasteners, and any places where water has gotten under the old roof. Overlay saves tear-off labor and disposal cost, but it’s only viable if the existing roof is in good shape and flat enough to support the new panels without telegraphing waves.

2. Underlayment, Ice Protection, and Ventilation

Even though galvalume panels are extremely weather-tight, building codes and best practices require a secondary water barrier. We roll out synthetic underlayment-usually a slip-resistant product rated for high-temp applications, since metal roofs can get hot under summer sun. At eaves, valleys, and around penetrations, we install self-adhering ice-and-water barrier strips. These create a sealed plane that catches any wind-driven moisture that sneaks past panel seams during extreme storms.

Ventilation is critical under metal roofs to prevent condensation and manage attic heat. We evaluate existing soffit intake and ridge or gable exhaust vents and add or upgrade them as needed. On some projects, we’ll install a vented batten system or use a raised-seam clip that creates an air gap between the underlayment and the panels, allowing continuous airflow to vent moisture and heat. Proper ventilation extends the life of both the galvalume panels and the roof deck.

3. Panel or Shingle Layout and Attachment

Layout starts with establishing straight lines-usually a chalkline snapped parallel to the eave or ridge. For standing seam, we set a starter strip or edge trim at the eave, then begin laying panels from one rake edge, working across the roof. Each panel locks into the previous one via a male-female seam edge, and concealed clips screwed to the deck hold the panels down while allowing thermal expansion and contraction.

Clip spacing and fastener type are dictated by engineering-typically every 12 to 18 inches on-center along the seam, using #14 pancake-head screws into solid deck or structural purlins. We double-check every clip is seated flat and every screw is snug but not over-driven; over-tightening can dimple the clip and reduce holding power. For exposed-fastener panels, screws go through the high ribs (not the flat pans where water runs) with neoprene washers to seal the penetration. Every screw line is laid out with a string or laser to keep rows straight and professional-looking.

4. Flashings, Trims, and Final Detailing

The ridge cap is where two roof planes meet at the peak. On a standing seam galvalume roof, we use a vented ridge cap that allows hot air to exhaust while keeping rain and snow out. The cap is secured to the ridge with clips or concealed fasteners, matching the panel profile. Rake trims cover the gable edges, and eave trims seal the bottom edge and create a drip edge to keep water away from fascia boards.

Wall flashings-where the roof meets a vertical surface like a chimney, dormer, or sidewall-are custom-bent from matching galvalume coil and sealed with high-grade polyurethane or butyl sealant. Pipe flashings around vent stacks use neoprene boots or lead-free metal collars designed to flex with the panel profile. Every penetration is a potential leak point, so we take extra time to ensure sealant coverage and mechanical attachment are both correct.

Final walkthrough includes checking panel alignment, verifying all fasteners are covered or sealed, inspecting underlayment exposure at any cut edges, and cleaning metal shavings and sealant smears off the panels. Galvalume panels can be walked on, but we use roof pads or walkboards to avoid scuffing the paint finish. Once the client signs off, we haul away all waste and leave the site cleaner than we found it.

Maintenance and Lifespan of a Galvalume Metal Roof

Routine Checks and Cleaning

A properly installed painted galvalume roof in Nassau County should last 30 to 50 years with minimal intervention. Annual or biannual inspections-either from the ground with binoculars or a quick professional walk-catch small issues before they become expensive. Look for debris buildup in valleys, leaves clogging gutters, or any panels that have lifted or shifted after high winds.

Cleaning usually means hosing off dust, pollen, and salt residue once or twice a year. A garden hose and a soft brush are enough; avoid pressure washers that can force water under seams or damage the paint. Keep tree branches trimmed back so they don’t rub the finish, and clear gutters regularly so water doesn’t back up under the eave trim.

Watching for Coating Wear and Fastener Issues

PVDF paint finishes on galvalume are extremely durable, but over 20 to 30 years you may see slight fading or chalking, especially on south-facing slopes. That’s cosmetic; the underlying galvalume substrate remains protected. If you do see bare metal showing-from a scratch, impact, or failed paint-touch it up promptly with manufacturer-supplied touch-up paint to prevent localized rust.

On exposed-fastener systems, the neoprene washers under screw heads will harden and crack after 15 to 20 years of UV and temperature cycling. When that happens, water can wick under the screw head and cause rust staining or deck rot. Plan for a fastener inspection and possible re-sealing or screw replacement at the 15-year mark. Standing seam systems with concealed clips avoid this issue entirely, which is why they cost more up front but save money over the roof’s life.

Working with a Nassau County Roofer on a Galvalume Installation

Questions to Ask About Galvalume Experience

• How many galvalume roofs have you installed in the past two years, and what panel systems? You want a contractor who works with the material regularly, not someone experimenting on your dime.
• Which galvalume manufacturers do you source from, and why? Brand matters-reputable mills like ATAS, McElroy, Berridge, or Fabral have track records and warranty support. A contractor using no-name import coil is a red flag.
• How do you handle coastal exposure and edge sealing? The answer should include site evaluation, possible upgrade to heavier paint or aluminum for extreme zones, and specific edge-sealing or touch-up protocols.
• What does your galvalume warranty package include? You should get a written workmanship warranty from the contractor (typically 5 to 10 years) plus the manufacturer’s material and paint warranties transferred to your name.

Understanding Warranties and Specifications

Galvalume material warranties typically cover substrate perforation for 20 to 25 years and may extend to 30 years if the coating weight is heavier. Paint warranties on PVDF finishes usually cover color fade and chalking for 25 to 40 years, depending on color family-lighter and more neutral colors hold up better than deep reds or blues. Both warranties are prorated, meaning if a failure happens at year 15, you’ll receive partial credit, not full replacement.

Workmanship warranties from your contractor cover leaks, fastener failures, improper flashing, and installation defects. Make sure this is in writing and clarify what maintenance you’re required to do to keep the warranty valid-most require annual inspections and prohibit pressure washing or harsh chemical cleaners.

Frequently Asked Questions About Galvalume Metal Roofs

Will a galvalume roof rust?
The galvalume coating greatly reduces red rust compared to plain galvanized steel, but edges where panels are cut, areas where the coating is scratched or damaged, and severe exposure zones can still corrode. Proper edge sealing, touch-up paint on cut ends, and keeping debris off the roof minimize this risk. In Nassau County’s moderate-coastal environment, a painted galvalume roof maintained correctly should not show rust for decades.

Is galvalume safe to use right on the coast?
Manufacturer guidelines often limit bare galvalume in the “severe marine” zone-within 500 to 1,000 feet of breaking surf where salt spray is constant. In those areas, aluminum or a premium painted galvalume system with heavier topcoat and edge protection is recommended. For properties further inland or shielded by other structures, painted galvalume performs very well. A local roofing pro should evaluate your specific site before specifying the substrate.

Does galvalume cost less than aluminum roofing?
Yes. Painted galvalume standing seam typically runs $9.50 to $13 per square foot installed in Nassau County. Aluminum standing seam runs $13 to $18 per square foot. The cost difference reflects material pricing-aluminum coil is more expensive-and slightly higher labor because aluminum’s softness requires more care during handling and fastening. For non-extreme coastal sites, galvalume offers better value.

Can galvalume be used under solar panels?
Absolutely. Galvalume standing seam is one of the best substrates for roof-mounted solar because the raised seams accept clamp-on solar rail brackets that don’t penetrate the roof. No new holes means no new leak points. Your solar installer should use S-5! or equivalent clamps engineered for your specific panel profile, and coordination between the roofer and solar contractor ensures the roof layout accommodates both the panel seams and the array framing.

Do you install galvalume metal roofs in Nassau County?
Yes. TWI Roofing designs and installs painted and bare galvalume standing seam, exposed-fastener, and metal shingle systems throughout Nassau County. We’ll evaluate your property’s distance from saltwater, roof pitch, aesthetic goals, and budget, then recommend the galvalume system-or an alternative like aluminum if your exposure is severe-that makes the most sense. Request a site assessment and written proposal to see costs, timelines, and warranty details specific to your home.

Turn Galvalume from a Line Item into a Well-Designed Roof

Galvalume metal roofing offers Nassau County homeowners a rare combination: proven long-term corrosion resistance, lower cost than aluminum, and a broad palette of profiles and colors to match any architectural style. But “galvalume” alone isn’t a complete specification-it’s a substrate that performs best when matched to your specific site exposure, paired with the right paint system and profile, and installed with attention to edge details, fasteners, and ventilation.

Whether you’re replacing worn-out asphalt shingles on a colonial in Levittown or upgrading a commercial building in Westbury, a conversation about galvalume should include your distance from saltwater, roof slope, visibility, maintenance expectations, and long-term plans. That discussion helps us choose between standing seam or shingles, bare or painted, standard or heavy-duty topcoat, and whether galvalume or aluminum ultimately makes more sense.

Schedule a roof evaluation with TWI Roofing and bring your questions-about warranties, installation timelines, panel samples, and exactly how we’ll detail flashings and seams for Nassau County weather. The best galvalume roof isn’t the one that checks a box on a spec sheet; it’s the one designed and built for your house, your budget, and your piece of Long Island.