Types of Metal Roofing, Explained Without the Sales Pitch

You asked two or three roofers for a metal roof and the paperwork came back speaking different languages. One says standing seam. One says 26-gauge rib panel. A third mentions stone-coated steel shingles. They are all metal roofs, and they are all legitimate products, but they attach differently, look different and belong on different buildings.

This guide is the vocabulary lesson, not a ranking. The company's Anderson page lists standing seam, corrugated and stone-coated steel among the options it installs, and its residential metal roofing page covers everything from two-story homes to hobby shops and doublewides. Knowing which type is being quoted is the first step to comparing them fairly.

Standing seam panels run from ridge to eave with their edges turned up into vertical seams that lock together. Clips hidden inside the seam hold the panels to the deck, so no screws pass through the face of the metal. The Insurance Institute for Business and Home Safety (IBHS) lists standing seam and snap lock as the two concealed-fastener panel families, and the Metal Roofing Alliance also calls this style vertical seam.

Because nothing pins the pan, the panels can expand and contract along their length, which is why standing seam suits long roof runs and finished buildings where leaks and fastener upkeep are unwelcome. The 2021 International Residential Code (Section R905.10.2) allows standing-seam systems down to one-quarter unit vertical in 12 units horizontal, lower than any other metal roof type. The guide on how a standing seam roof works goes through the parts in detail.

This is the barn roof most people picture. Panels overlap at their edges and are fastened with screws driven through the face of the metal into purlins or decking. IBHS names 5-V, rib and tile-profile panels as the common exposed-fastener types and notes that, because the sides overlap, they are considered lapped panels. The Metal Roofing Alliance calls the same family thru-fastened panels and groups agricultural panels with them.

The screws seal with a rubber washer under the head. The IBHS low-slope metal guide says exposed fasteners must include EPDM washers and warns against over- or under-tightening them. IBHS also notes that the rubber gaskets around exposed fasteners can deteriorate with age and that fasteners can back out and need to be reinstalled, so these roofs want a periodic look from the ground. Because the laps are not watertight on their own, the IRC requires more slope: 3 in 12 without lap sealant, or one-half in 12 with approved lap sealant (Section R905.10.2).

Exposed-fastener panels are generally less labor to install, and they are the normal choice for barns, equipment sheds, carports, porches and shops. The company's post on metal panels for agricultural buildings covers ventilation, coatings and livestock conditions. The standing seam vs. exposed-fastener guide compares the two head to head.

Not every metal roof looks like metal. The Metal Roofing Alliance options guide describes pre-formed metal shingles, metal shake, metal tile and metal slate, each made to mimic the traditional material and offered painted or stone-coated. The IRC treats these as metal roof shingles: Section R905.4.1 calls for a solid or closely fitted deck unless the product is designed for spaced sheathing, and Section R905.4.2 sets a minimum slope of 3 in 12.

• Metal shingles and shakes. Interlocking stamped pieces, often with a textured or embossed face, installed in courses like asphalt shingles. Common on homes where the owner wants metal without a panel look, or where a neighborhood's rules favor a shingle appearance.
• Metal tile and slate look. Panels or pieces shaped with the curves of clay tile or the flat face of slate. The MRA points out that these carry far less weight than real tile or slate, which matters on older framing.
• Stone-coated steel. Steel shingle, shake or tile panels coated with an acrylic adhesive and a layer of granules, then a clear sealer, according to the MRA's colors and coatings page. The MRA glossary adds a caution: stone-coated roofing faces similar streaking, granule-loss and organic-growth issues as composition shingles, so it still needs attention in shade or under trees.

The same roll-forming that makes roof panels also makes wall panels. The company's commercial metal page lists insulated, single skin, concealed fastener, exposed fastener and interior wall liner panels, in 22-, 24-, 26- and 29-gauge, for retail, self-storage, educational, residential, agricultural and industrial buildings. The attachment logic is the same as on a roof: concealed or exposed.

Under every one of these types sits a choice of metal. The Metal Roofing Alliance describes steel as the most common roofing metal, treated with a metallic coating to prevent rust and typically the most affordable; aluminum as lighter with increased corrosion resistance for marine and coastal homes; and copper and zinc as natural metals that develop a patina. The steel vs. aluminum vs. copper guide compares them for an inland Upstate roof.

A fair match of type to building saves money and trouble later. Here is the pattern you will generally see across Anderson, Oconee and Pickens counties, with the usual exceptions.

• Homes: standing seam for a modern or farmhouse look; metal shingles or stone-coated steel where the owner wants a shingle or tile appearance; exposed-fastener panels on budget builds, porches and additions.
• Barns, sheds and equipment buildings: exposed-fastener panels on open purlins, with coating and ventilation chosen for the use. The company's post on commonly used residential roofing materials puts metal alongside asphalt, slate and tile for comparison.
• Shops and garages: either, depending on finish level; a heated, finished hobby shop often gets standing seam, a cold storage building gets exposed-fastener panels.
• Churches and commercial buildings: standing seam on sloped roofs, membrane systems where the roof is near flat, and metal wall panels on the sides.
• Historic buildings: copper, terne-coated or other sheet metals matched to the original; see the historical roofing restoration page.
• Nearly flat roofs: usually not a lapped metal panel at all. Look at the flat roof systems page before deciding.