Standing seam, exposed-fastener panels or metal shingles
Standing seam panels interlock or are seamed together along a raised vertical seam, according to the National Roofing Contractors Association (NRCA). Hidden clips or a fastening flange let them expand and contract. The Metal Construction Association (MCA) calls clip-attached systems premium over face-fastened panels for weathering and durability, at a modest increase in cost, since clips allow movement without piercing the weather surface.
Exposed-fastener panels, also called through-fastened or screw-down, are screwed through the face with a washer at each screw, and neighboring panels overlap at side laps. McElroy Metal, which makes both kinds, says they cost less than standing seam, but screw holes can enlarge as panels expand and contract, especially long panels.
Metal shingles are smaller units, under 3 square feet of exposure each by the International Building Code definition NRCA quotes. They can take the shape of asphalt, tile, slate or wood shingles, and some are stone-coated with asphalt-type granules, says the Metal Roofing Alliance (MRA), an industry group.
| Type | Fastening | Lowest pitch | Deck | Ice barrier |
|---|---|---|---|---|
| Standing seam | Hidden clips or flange | 1/4 in 12 (R905.10.2) | Solid or spaced sheathing (R905.10.1) | Not named (R905.1.2) |
| Exposed-fastener panels | Screws through the panel | Lapped, nonsoldered seams: 3 in 12, or 1/2 in 12 with lap sealant (R905.10.2) | Solid or spaced sheathing (R905.10.1) | Not named (R905.1.2) |
| Metal shingles | Manufacturer's instructions (R905.4.5) | 3 in 12 (R905.4.2) | Solid or closely fitted (R905.4.1) | Required (R905.1.2) |
Deck rules exempt products designed for spaced supports or sheathing. Code sections are from the 2021 International Residential Code (IRC) as adopted in the 2022 Connecticut State Building Code, whose successor, expected July 1, 2026, is delayed (Department of Administrative Services, checked September 17, 2026).
Metal over existing shingles: what the code allows
The code permits a recover, new roofing over old (R908.3.1), when the new roof covering is installed to its manufacturer's approved instructions; when it is a complete and separate system, such as standing-seam metal, that carries roof loads directly to the structure; or when metal goes over wood shakes under the conditions of R908.4. A recover is never allowed over two or more layers, a water-soaked or deteriorated roof, or slate, clay, cement or asbestos-cement tile (R908.3.1.1), and rusted, damaged or deteriorated flashings and vents are replaced (R908.5). Connecticut's permit exemption for roof work covers only repairs limited to 25 percent of the roof covering within one calendar year (R105.2), so a new metal roof needs a permit. Our roof replacement page covers tear-offs.
Underlayment and ice barrier under metal
Connecticut's version of R905.1.1 applies to metal panels and metal shingles: underlayment over the entire roof, on top of a self-adhering membrane strip at least 4 inches wide over every deck joint. The strips aren't needed when self-adhering ASTM D1970 underlayment covers the roof, or on roofs sheathed with lumber less than 3 feet in nominal width. NRCA recommends at least No. 30 felt and a separate slip sheet under architectural metal panels.
The ice barrier rule (R905.1.2) names metal shingles, not panels: from the lowest roof edge to at least 24 inches inside the exterior wall line, and at least 36 inches up the slope at 8 in 12 or steeper. Beyond the code, the MCA says many designers in snow country add self-adhering membrane at eaves, valleys and transitions. It says the membrane should reach at least 30 inches inside the heated building and have a softening point suited to roof temperatures that can approach 200°F.
Snow, snow guards and ice dams in Connecticut
Appendix AY sets Connecticut ground snow loads of 30 to 40 pounds per square foot. The MCA's cold-climate bulletin explains that sun warming the roof through the snow can release the whole accumulation from one or both sides of a metal roof at once. It advises keeping entrances, walkways and parking out of the drop zone.
Snow guards are most effective concentrated near the eave, the MCA says. On standing seam it prefers tested guards that clamp to the seam without puncturing the panel, and it warns against screwing guards through panels designed to move, or relying on adhesive-mounted guards as the primary system.
Ice dams form on every type of roof, not only metal (MCA). The Department of Energy's Building America Solution Center names three ways builders fight them: air seal the ceiling, insulate the attic and ventilate the roof. NRCA advises against removing ice dams or shoveling the roof yourself.
Wind ratings and Connecticut design wind speeds
Appendix AY sets each town's ultimate design wind speed, from 115 mph in 21 towns, most in Litchfield County, to 129 mph in Stonington. Roof coverings must resist the code's component and cladding wind loads (R905.1), and metal panels are secured per the code and the manufacturer's instructions (R905.10.4). Metal shingles on a solid or closely fitted deck must pass a named wind test (R905.4.4.1). Find your town's figure on our Connecticut roofing town pages. In Westchester, Putnam and Dutchess Counties, the 2025 Residential Code of New York State applies instead; ask your local building department.
Steel, aluminum, copper and zinc
Steel is the most common metal roofing material and typically the most affordable, and all steel roofing carries a metallic coating against rust, according to the MRA. The code lists minimum coatings such as G90 galvanizing and AZ50 aluminum-zinc, with paint systems applied over them (Table R905.10.3(2)). The MRA says aluminum, lighter and more corrosion resistant, suits marine and coastal homes. Copper and zinc weather to a protective patina. Code minimums include 16-ounce copper (12-ounce high-yield), 0.027-inch zinc and 0.024-inch roll-formed aluminum panels (Table R905.10.3(1)).
Paint finishes: PVDF (Kynar 500) and SMP
PPG, which makes coatings of both types, names PVDF (polyvinylidene fluoride) and SMP (silicone-modified polyester) as two commonly used coil-coating resins. It credits PVDF with long-lasting resistance to chalking and fading and calls 70% PVDF formulations the gold standard, and says SMP is popular for residential, industrial and agricultural uses for its competitive pricing and durable finish. Kynar 500 is Arkema's PVDF resin, used as the base of long-life coatings for metal roofing.
Noise, lightning and heat
Noise. The MRA says there is little difference between metal and other materials in noise from rain or hail, crediting the solid deck, underlayment and attic insulation beneath modern metal roofs.
Lightning. The MCA's lightning bulletin says metal roofs neither attract lightning nor protect a building from it. Protection comes from a lightning protection system, installed to NFPA 780.
Heat. The EPA lists metal shingles or tiles with reflective paint or granules among cool roof products for steep roofs. The MCA notes conventional dark colors run much hotter than green, blue or white, though cool pigments can lower that, and for snow country it lists a sun-absorbing color among ways to reduce icing.
What a metal roof costs
The MRA says a metal roof costs more up front than an asphalt shingle roof, and that a roof's shape and pitch affect installation cost more than the style of metal chosen, so a contractor needs to see the roof. Our roof replacements in general start at around $650 per roofing square (100 square feet) and rise with the material, the layers torn off, the pitch, decking repairs, chimneys, skylights and access. Our inspections are free, and financing is available with approved credit through Service Finance Company and Hearth.
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Common questions about metal roofing in Connecticut
Can a metal roof go over my existing shingles in Connecticut?
Sometimes. The code allows it when the new roofing follows its manufacturer's approved instructions or is a separate system, such as standing seam, that carries roof loads to the structure (IRC R908.3.1), never over two or more layers or a water-soaked or deteriorated roof (R908.3.1.1).
Do I need ice and water shield under a metal roof?
Under metal shingles, yes: Connecticut requires an ice barrier from the eave to at least 24 inches inside the exterior wall line (R905.1.2). The rule doesn't name metal panels, but the Metal Construction Association says many designers in snow country add self-adhering membrane at eaves and valleys.
Do I need snow guards on a metal roof?
The Metal Construction Association says to leave snow retention off only in carefully selected situations, since sun-warmed snow can release from a metal roof all at once. On standing seam, it prefers tested clamp-on guards that don't puncture the panels.
Does a metal roof attract lightning?
No. The Metal Construction Association says a metal roof is no more or less likely to be struck than any other roof; terrain, the building's height and size, and how often storms hit the area set the odds.
How long does a metal roof last?
The Metal Roofing Alliance says 30 to 50-plus years, since metal roofs can often be repainted instead of replaced. InterNACHI's life expectancy chart gives metal 40 to 80 years, depending on weather, design, material quality and maintenance.
Related roofing pages
Sources: 2022 Connecticut State Building Code and the 2021 IRC as adopted; Connecticut DAS; New York Department of State; NRCA; Metal Construction Association; Metal Roofing Alliance; McElroy Metal; PPG; Arkema; InterNACHI; EPA; DOE Building America Solution Center; NFPA. Checked September 17, 2026.