Metal is a traditional roof on the peninsula and on Sullivan's Island. Here is how the panel types differ, what salt air asks of the metal and its screws, how panels stay put in a hurricane, and what the historic boards allow.
A metal roof near the harbor has two jobs. It has to stay attached when the design wind on the building department's table reads 140 or 150 mph, and it has to keep its coating and fasteners intact in salty air. The failures FEMA's advisory on metal roofs pictures after Hurricane Ike come down to details more than to the panels themselves: a clip set too far from the eave, a ridge cap with too few screws.
This page walks through the choices in the order they come up: the kind of panel, the slope it needs, the metal and the fasteners for your distance from the ocean, the attachment details federal storm investigators keep pointing to, the underlayment beneath it all, the rules in the historic districts, and what moves the price.
FEMA's recovery advisory on metal roofs in high-wind regions sorts the common options into a few families, and the difference matters for how the roof is held down:
The advisory also separates panels built to hold out water under pressure, with sealant in the seams, from panels that only shed water and so need more slope and an underlayment beneath. Two roofs that look alike from the street can be very different systems, so ask which kind a quote prices.
South Carolina's residential code (the 2021 International Residential Code as the state amended it) sets a minimum slope for each kind of metal covering:
| Covering | Lowest slope the code allows | Section |
|---|---|---|
| Standing-seam panel systems | 1/4 inch of rise per foot (1/4:12) | R905.10.2 |
| Lapped, nonsoldered seams with lap sealant | 1/2:12, sealant applied per the maker | R905.10.2 |
| Lapped, nonsoldered seams without sealant | 3:12 | R905.10.2 |
| Metal roof shingles | 3:12 | R905.4.2 |
That spread is why standing seam shows up on porch roofs and shallow additions where shingles are not allowed at all (asphalt shingles need at least 2:12). It is also why a through-fastened panel on a low porch roof leaks: the laps were never meant to hold water that sits. If part of your house is close to flat, the flat roofing page covers the membrane route, and a standing-seam system is the metal option for it.
The code requires metal roofing to be naturally corrosion resistant or coated, and Table R905.10.3(2) lists the minimum coatings for steel: 55 percent aluminum-zinc alloy coated steel at AZ50 (ASTM A792), 5 percent aluminum alloy coated steel at GF60 (ASTM A875), aluminum-coated steel at T2 65 (ASTM A463), galvanized steel at G-90 (ASTM A653), and prepainted steel (ASTM A755). Those are floors, not recommendations for a house a few blocks from the water.
Fasteners get the same attention. Where the panel maker gives no instructions, Section R905.10.4 calls for galvanized fasteners on steel roofs, copper, brass, bronze, copper alloy or 300-series stainless steel on copper roofs, and allows stainless on any metal roof. FEMA goes further for the coast: on roofs within 3,000 feet of the ocean line, its advisory recommends stainless steel clips and fasteners. For copper roofs where the basic wind speed is over 90 mph, it recommends Type 316 stainless clips and stainless screws in place of soft copper clips.
Published design wind speeds here start at 133 mph, the floor Berkeley County sets for plans outside its towns, and reach 150 mph on the peninsula and at Folly Beach (the roofing code guide lists each). FEMA's advisory, written after Hurricane Ike, names the details that decided which metal roofs stayed on:
Under metal, the underlayment is the backup roof. In areas where the code requires wind design, Table R905.1.1(1) calls for ASTM D226 Type II felt or ASTM D4869 Type III or IV under metal roof panels, and Charleston County's Roof Underlayment Form, which the roofer signs with the permit, lists metal panels and metal shingles among the coverings that go over two lapped layers or one of the self-adhering alternatives the form allows.
FEMA's advisory gives two reasons to take this seriously. A sturdy underlayment can serve as a secondary water barrier if the panels are blown off, and one of its photographs shows the underlayment still in place where a large number of panels had gone. And the details differ from a shingle roof: where its shingle guidance calls for Type I (#15) felt, it recommends Type II (#30) under metal, because the heavier sheet resists punctures while panels go on. A self-adhering membrane under metal should be a product made for that use, since those resist the bitumen running in high heat.
Several of the places we cover review roof changes in their historic districts, and metal is where their rules are most specific:
The City of Charleston wants the manufacturer's specifications filed with any metal roof permit, and Folly Beach wants specifications showing the roofing and underlayment meet its 150 mph requirement. Most other jurisdictions here list roofing as permitted work; each town page under roofing by city says who issues the permit. We pull it.
Can metal go over the shingles you have? Section R908.3.1 allows a complete standing-seam system that carries its load straight to the framing, and R908.3.1.1 rules out a recover when the old roof is wet, rotten or already two layers thick. FEMA's advisory shows a house where 5V-crimp panels were screwed to nailers over old shingles; the nailers let go and the panels landed on the lower roof. Our metal replacements start from the bare deck, so the wood gets walked and any rotten sheathing gets replaced before anything covers it again.
We could not find a published, current regional price for a metal roof in this part of the Southeast that we were willing to print, so here are the things that move a real quote:
Sometimes, under the code. A complete standing-seam system that carries its load to the framing may go over an existing roof, but the old roof cannot be wet, rotten or already two layers deep. FEMA has documented panels screwed to nailers over shingles blowing off. Our replacements start from the bare deck.
Coated steel can last near salt water, but the coating and fasteners have to suit the spot. The code sets minimum coatings such as AZ50 and G-90, and FEMA recommends stainless steel clips and fasteners on roofs within 3,000 feet of the ocean line. Ask for both to be named on the quote.
Often yes, if it is the kind of metal the board expects. The Board of Architectural Review's roofing policy asks for historic roofs to be mended or matched, and its standing seam is crimped by hand. A snap-lock panel will not get through review on a historic building.
A standing-seam system can go down to 1/4 inch of rise per foot under the residential code. Lapped panels need 3:12 without sealant or 1/2:12 with lap sealant, and metal shingles need 3:12. Below those, a membrane or a standing-seam system is the answer.
Yes. Where wind design is required, the code calls for Type II felt or an equivalent rated sheet under metal panels, and Charleston County's underlayment form lists metal among the coverings that get two layers or a self-adhering alternative. If the panels are ever lost, that layer is what keeps rain out.
Not by themselves. FEMA notes that exposed fasteners make it easy to check that enough went in. Concealed clips work well when they are close to the eave and doubled along the edges; one roof FEMA photographed had its eave clips 13 and 17 inches from the deck edge.
Metal roofing across greater Charleston, from the sea islands and beach towns to Summerville, Goose Creek and Moncks Corner. Each city has its own page with the permit rule and code edition that apply there:
Sources: 2021 International Residential Code as adopted in South Carolina, Chapter 9: R905.1.1, R905.4.2, R905.10.2, Table R905.10.3(2), R905.10.4, R908.3.1, R908.3.1.1 (UpCodes viewer) · FEMA, Metal Roof Systems in High-Wind Regions, Hurricane Ike Recovery Advisory (copy posted by the Town of Edisto Beach) · U.S. DOE Building America Solution Center, listing for the FEMA metal roof advisory · Charleston County Building Inspection Services, Roof Underlayment Form (2021 code) · City of Charleston, roof permit guideline (manufacturer's specifications for metal) · City of Charleston, Board of Architectural Review policy statement for roofing · City of Charleston design criteria table (150 mph) · City of Folly Beach, 2026 permit packet (150 mph roofing requirement) · Berkeley County Codes Enforcement (133 mph minimum) · Town of Sullivan's Island, Historic District Design Guidelines, Chapter 4 · Town of Mount Pleasant, Old Village Historic District Guidelines · Town of McClellanville, Historic District Design Review Manual · Town of Summerville, Historic District Design Guidelines · Town of Rockville, Design Review Board. Codes, programs and prices change; confirm the current rule with your city before you rely on it.
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