Aluminum Roofing Types for Houses Near Salt Water
Aluminum comes in most of the shapes steel does. These are the four parts of an aluminum roof to get quotes on.
Aluminum Standing Seam Panels
Aluminum standing seam comes in the same snap-lock and mechanically seamed profiles as steel. The code minimum for aluminum roll-formed panels is 0.024 inch (ASTM B209), but the standing seam data sheets we read list heavier metal: .040 inch for one maker's 2-inch mechanical seam panel and .032 to .040 inch for its 1.5-inch snap-lock panel.
The same sheets list the aluminum panels narrower than the steel ones: 16 inches against 18 for the mechanical seam, and 15 against 19 for the snap-lock. Narrower panels mean more seams and more clips across the same roof. Seam types and heights are compared on Standing Seam Metal Roofs.
Aluminum Shingles and Shakes
Press-formed aluminum shingles are stamped to look like shakes, slate or tile. The building code's minimum for them is 0.019 inch, a little under the panel minimum above. A cost guide notes that aluminum roofs come in both shingles and panels.
Shingles suit a house where standing seam would look out of place. Every metal shingle has to pass a code wind test; those tests are listed on Metal Shingles.
PVDF-Painted Aluminum
When aluminum is painted, the finish is where quotes differ. Finishes sold under the Kynar 500 name have to contain at least 70% PVDF resin by weight under Arkema's licensing terms and meet the AAMA 2605 performance specification. The resin maker recommends getting validation from the paint licensee that a finish really contains it.
Arkema describes these finishes as having a proven record under severe ultraviolet exposure for more than 25 years, which counts on a roof that takes full Lowcountry sun. On the estimate, ask for the finish by name and resin type, not "premium paint" or "coastal-rated finish". The same specification covers factory finishes on galvanized and aluminized steel, so a PVDF name alone doesn't tell you the panel underneath is aluminum.
Aluminum Trim, Clips and Fasteners
An aluminum roof is only as corrosion-resistant as its weakest part. Without manufacturer instructions, the 2021 IBC accepts aluminum fasteners for aluminum roofs attached to aluminum supports, and stainless steel fasteners on any metal roof. A steel coil maker's galvanic corrosion bulletin goes further for salt air, recommending that stainless hardware be used with aluminum panels in corrosive environments.
Ask for the drip edge, rake trim, ridge and flashings in aluminum too. A steel trim piece on an aluminum roof puts the less corrosion-resistant metal at the edges of the roof.
Why Charleston homeowners call Charleston Metal Roofing Co.
- Estimate at no cost to you
- Metal, seam and fasteners named on paper
- Your request goes to a single local roofer
- Referral is free; you pay only the roofer you hire
Aluminum Roofing and Steel Warranty Distances From Salt Water
In Charleston, the argument for aluminum starts with the fine print on steel warranties. Two manufacturers' Galvalume warranties, both read in full, set these distance limits:
| Warranty | Surf coastline | Large bay | Marsh or canal |
|---|---|---|---|
| 25-year acrylic-coated AZ55 Galvalume (one maker) | must be at least 2,800 ft away | at least 1,200 ft | at least 600 ft |
| 50-year PVDF-painted AZ50 Galvalume (another maker) | excluded within 1,500 ft | within 800 ft | within 400 ft |
Both warranties also exclude areas under repeated or constant salt or fresh water spray. The 25-year warranty goes further, excluding areas sheltered from washing by rainfall, such as the undersides of eaves and soffits, and areas that take run-off from lead or copper flashing. That matters on Charleston's raised houses and piazzas, where a lot of metal sits under deep eaves out of the rain.
Measure from the house to the nearest marsh edge and tidal creek as well as the harbor or ocean, since each has its own limit. If a steel roof is proposed inside those lines, ask for the panel maker's warranty terms for your address in writing.
Aluminum Roofing Cost in Charleston
A national cost guide prices aluminum roofing at $700 to $1,700 per square installed, where a square is 100 square feet of roof. Materials alone run $300 to $900 per square in the same guide. That works out to roughly $7 to $17 per square foot installed. The same guide prices Galvalume and galvanized steel roofing at $500 to $1,300 per square installed, and puts a typical whole aluminum roof at $10,500 to $42,500 against $7,500 to $32,500 for Galvalume. Its standing seam figures are on Metal Roof Replacement.
So aluminum costs more at both ends of the range, and the gap is the price of not depending on a warranty distance. On a house well inland of the marsh lines above, painted steel may be the better use of the money; close to the water, the comparison is aluminum against a steel roof the panel maker won't stand behind.
No public source we found lists Charleston aluminum prices, so a measured local estimate is the number to plan around.
Aluminum Roofing Estimates: What to Check
Distance first
Where the house sits against the surf, bay and marsh limits above, and whether steel would be warranted there at all.Thickness in inches
Panel or shingle thickness, with the data sheet attached.Finish by name
The paint system and its resin, with the licensee's confirmation if it's sold as Kynar 500.Matching trim and fasteners
Aluminum trim and flashing, and the fastener and clip metal the panel maker specifies.Uplift test
The tested assembly for that aluminum panel and thickness. Charleston's design wind speed is on Hurricane Metal Roofs.