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Metal roof materials

Aluminum vs Steel Metal Roof: Which Is Better in Florida?

Aluminum does not rust, so it is the usual choice for roofs near salt water. Steel is stronger against dents, moves less in heat and costs less, but many steel warranties stop within 1,500 feet of the coast. Distance from the water should decide which metal you buy.

By Josh Hildebrand, owner of Coastline Roofing · Florida license CCC1331076 ·

You are weighing two metals and one of them costs more. Here is what each does well, and where Florida salt air changes the answer.

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The basics

What is the difference between an aluminum and a steel metal roof?

Steel is strong and costs less but can rust. Aluminum does not rust, which is why it is the usual pick near salt water.

Steel roofing panels are a steel core with a metal coating (zinc or aluminum-zinc), often with paint on top. If the coating is scratched through or cut, the steel under it can rust. Aluminum is a different metal. Sheffield Metals explains that aluminum forms a hard oxide film on its surface that protects it, so it does not make red rust the way steel does.

That one trait explains most of the advice you will hear. Sheffield says aluminum is almost always recommended in coastal areas where salt water is present. Many steel roof warranties, by contrast, stop near the coast. We cover those on our Galvalume vs galvanized page.

Aluminum is not simply better, though. It dents more easily, it moves more with heat, and it usually costs more. The right choice depends on how close your home is to salt water, and on what you need from the roof.

Close to the water and unsure about metal?

Coastline installs 24-gauge standing seam and 5V crimp. An inspection with a written photo report shows what is on your roof and how it is aging. Coastline Roofing works all over Florida (license CCC1331076).

Call (941) 896-7793 or text your town and a photo.

Side by side

How do aluminum and steel metal roofs compare?

Aluminum wins on salt air and weight. Steel wins on denting, movement and price.

Aluminum and steel metal roofing compared
FeatureAluminumSteel (Galvalume or galvanized)
RustForms a protective oxide film, no red rustCan red rust if the coating is cut or worn through
Salt airAlmost always recommended near salt water, per SheffieldMany warranties stop within 1,500 feet of salt water
WeightA .032 inch aluminum roof weighs under 0.5 pound per square footA 24-gauge Galvalume roof weighs about 1 to 1.5 pounds per square foot
Strength and dentsTensile strength comparable to steel, but dents more easilyHarder surface, resists dents better
Heat movementExpands and contracts about twice as much as steelMoves less
Typical thickness.032 or .030 inch for homes24 or 26 gauge for homes
Material priceMid to high range, usually the premium optionLower than aluminum
WarrantySubstrate warranties usually about 20.5 years or less, with a rinse rule near the seaGalvalume substrate warranties typically run 15 to 25.5 years, with salt exclusions

Sources for the table: Sheffield Metals on aluminum and on warranty types; Florida Roof magazine and Metal Construction News on coastal practice. Weights and thicknesses are Sheffield's figures for its products, so other makers vary.

Corrosion. Sheffield calls aluminum much better than steel in corrosion resistance, especially in harsh coastal settings. It notes that aluminum is the metal most often installed in the Caribbean. Metal Construction News quotes an industry expert who says aluminum, stainless steel and copper are preferred in coastal settings.

Weight and strength. Sheffield says a .032 inch aluminum roof weighs under half a pound per square foot, where a typical 24-gauge Galvalume roof weighs 1 to 1.5 pounds. Tensile strength is comparable, but aluminum is more prone to dents. Florida Roof magazine quotes a Drexel Metals representative who says aluminum is lighter and corrosion resistant but softer, and handles severe hail less well.

Heat movement. Sheffield says aluminum expands and contracts about twice as much as steel. Restricting that movement can cause oil canning, noise and more maintenance, so it recommends expansion clips on mechanically seamed panels longer than 15 to 20 feet. See oil canning on metal roofs.

Price. In words, not numbers: Sheffield puts aluminum in the mid-to-high range for material cost, and it is the premium option next to steel. The roof total depends on the profile, the gauge, the finish and the roof shape. Our metal roof cost guide shows what moves the price.

Near salt water

Why is aluminum used near salt water, and when is steel still fine?

Distance from the water sets the answer. Here is how makers and trade writers frame it.

It does not rust

Aluminum's oxide film protects it from the red rust that attacks steel. That is the main reason it is used on the coast.

Steel warranties stop at the coast

McElroy's Galvalume paint warranty is void within 1,500 feet of salt water or where salt spray lands. Sheffield lists 1,500 feet for breaking surf, 800 feet for a large bay and 400 feet for a marsh.

Western States says avoid steel by the ocean

Western States Metal Roofing says metal near the ocean should not have a steel substrate, and that coastal paint warranties are based on an aluminum substrate.

Steel can still work with the right finish

Metal Construction News quotes an expert who would use at least G90 galvanized with a quality paint finish if steel must be used.

Coastal finishes exist

Florida Roof magazine notes Sherwin-Williams' Flurothane Coastal finish is designed for projects within 1,500 feet of the coastline, and a Garland consultant recommends a two-coat PVDF system for harsh coastal conditions.

Aluminum needs rinsing

Sheffield's warranty guide says coverage on pre-painted aluminum within one mile of a seacoast can be lost if the owner skips an annual fresh-water rinse. Read the clause.

Watch for

What can go wrong with an aluminum roof?

Dents, heat movement, metal contact and fasteners are the usual problems, and each has a fix.

Dents. Aluminum is softer. Walking on it and hail can mark it. That is a look issue more than a leak issue, but it is worth knowing.

Metal contact. Different metals touching can cause corrosion where water sits between them. McElroy's warranty excludes damage from runoff from copper, lead, nickel and stainless steel touching or draining on its panels. Ask your roofer how trim, fasteners and flashing metals are kept apart from the panels.

Fasteners. Florida Roof magazine quotes experts who say to use stainless steel fasteners on the coast, even for concealed-fastener roofs, and one cites FEMA guidance for full 300-series stainless within 3,000 feet of salt water. That quote is about fasteners, not panels. Ask what the fasteners are and why.

Thickness. Residential roofs typically use .032 or .030 inch aluminum, per Sheffield. Florida Roof magazine quotes a consultant who says the go-to on the coast is .040 or .050 inch. The 2010 Florida Building Code text quoted by DBPR sets 0.024 inch as the minimum for roll-formed aluminum panels. Ask for the thickness in writing.

Wind rating. A Boral representative quoted in Florida Roof magazine says warranty and wind performance for aluminum, copper and zinc may be lower than other materials. Whatever the metal, ask for the Florida Product Approval for the exact panel, deck and fastening.

A note on what Coastline installs

Coastline installs 24-gauge standing seam and 5V crimp metal roofs. If your home is close to salt water, tell us how close in your inspection request. We will look at what is on the roof, give you a written photo report and answer plainly.

How to decide

How do you choose between an aluminum and a steel roof?

Start with the distance from salt water, then weigh price, dents and the warranty.

  1. Measure the distance to salt water

    Gulf, bay, river or marsh. The warranty clause names a distance for each.

  2. Read the warranty for your address

    Find salt exclusions and rinse rules in writing, before you sign.

  3. Compare finishes

    PVDF is the common high-end paint. Ask whether it is coil applied and what the paint warranty covers.

  4. Ask about fasteners and trim

    Material, type and how dissimilar metals are kept apart.

  5. Compare total cost, not panel price

    Weigh the premium for aluminum against how much longer a steel roof would last at your address.

Who and when. Coastline Roofing is a Palmetto-based Florida roofing contractor, and Josh reviews every job through photo reports. The best time to ask is before you sign a metal roof contract, because the metal and warranty are set when the order goes in. If your roof is already up and showing rust, see is my metal roof rusting.

Where. Much of Manatee County sits on Tampa Bay, the Manatee River or the Gulf, so salt air is a real question here. Our best roofing for coastal Florida page compares other materials, and our salt air warranty guide goes deeper on the clauses. For styles, see standing seam vs 5V crimp and our metal roofing page.

Reviews

What homeowners say about working with Coastline

★★★★★
"From beginning to end the roof was done in 2 days. One night the crew stayed until 8:00. Each evening before leaving the crew ensured the yard was cleaned. We are so happy, and our roof is beautiful!"
Sharon T.Roof replacement
★★★★★
"Russell was great to work with. He was prompt in coming out to assess our roof and very knowledgeable. ... The job was complete in 2 days once work began."
Bryan S.Roof replacement
★★★★★
"Josh was especially amazing. He was professional, patient, and took the time to explain everything clearly so I felt comfortable and informed throughout the entire process. You can tell he genuinely cares about his customers and takes pride in his work."
Madison T.Roofing customer
Keep reading

Related guides

Metal Roofing

Standing seam and 5V crimp from Coastline.

See our metal roofing →

Metal Roof Cost in Florida

What moves the price of a metal roof.

Read the cost guide →

Galvalume vs Galvanized

The two steel coatings and their salt air limits.

Compare the coatings →

Also see metal roof rust in coastal Florida and stone coated steel roofing.

FAQ

More questions

Does aluminum roofing rust?

Not the red rust that steel gets. Sheffield says aluminum forms a hard oxide film that protects it. Aluminum can still corrode where it touches other metals with water between them, and some warranties require a regular fresh-water rinse near the coast. Fasteners and trim need to be chosen with that in mind.

Is an aluminum roof more expensive than steel?

Usually, yes. Sheffield puts aluminum in the mid-to-high range for material cost, and it is the premium option next to steel. Exact prices depend on the profile, thickness, finish and the roof's shape, so we keep numbers on our metal roof cost guide rather than here.

Is aluminum roofing strong enough for Florida wind?

Strength depends on the tested system, not just the metal. Sheffield says aluminum's tensile strength is comparable to steel. A Boral representative says wind performance for some non-steel metals may be lower than other materials. Ask for the Florida Product Approval for the exact panel, deck and fastening.

How close to salt water is too close for steel?

It depends on the maker. McElroy's paint warranty is void within 1,500 feet of salt water. Sheffield lists 1,500 feet for breaking surf, 800 feet for a large bay and 400 feet for a marsh. Metal Construction News says suppliers set limits that can range from 1,000 feet to a mile.

Does Coastline install aluminum roofs?

Coastline installs 24-gauge standing seam and 5V crimp metal roofs. If you are close to salt water and want to know what fits, ask for an inspection with a written photo report. We will tell you plainly what we would put on your roof and what we would not.

Sources

  1. Sheffield Metals: What is aluminum roofing?
  2. Sheffield Metals: Metal roof warranty types
  3. Sheffield Metals: Galvalume vs. Galvanized continuing education course
  4. Metal Construction News: Using metal in coastal environments
  5. Florida Roof Magazine: Metal Roofing by the Sea (October 2021)
  6. Western States Metal Roofing: Metal roofing in coastal areas, paint warranties
  7. McElroy Metal: Fluropon Kynar 500 PVDF with Galvalume substrates warranty
  8. Florida DBPR: Staff analysis for Declaratory Statement DS2014-002, quoting 2010 FBC Chapter 15 metal roof sections

Not sure which metal fits your home?

Josh will look at your roof and your distance to salt water and send you a written photo report with a straight answer.

Call (941) 896-7793 Text (941) 345-0072
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