Is a Metal Roof Loud in the Rain? What North Carolina Homeowners Hear

A metal roof installed on a house is usually only slightly louder than shingles in rain, and in most rooms the difference is hard to notice. What you hear indoors depends on the whole roof and ceiling assembly, not just the top layer. On a typical North Carolina home, rain hits the metal, which sits on underlayment over a plywood or OSB deck. Below the deck is an attic full of air, then insulation, then drywall. Each layer absorbs or blocks sound before it reaches the bedroom.

The noise reputation comes from a different kind of building. On a pole barn, carport or old screened porch, bare corrugated panels are screwed to open purlins with nothing underneath. The panel acts like a drumhead, and rain on it is loud. That is a real experience, but it is not how residential metal roofs are built.

Metal shingles, in particular, are formed with ribs, steps and profiles that make them stiffer than flat sheet, and they rest on the deck rather than spanning open space. Interlock aluminum shingles lock to each other on all four sides and are fastened through to the deck under each course.

Metal over open framing is loud because nothing stops the panel from vibrating and nothing absorbs the sound it makes. A thin sheet spanning two feet or more between supports flexes with each raindrop and radiates sound straight into the space below. There is no deck to stiffen it, no underlayment to dampen it, no attic air space to break up the sound path and no insulation to soak it up.

The model residential building code reflects the difference in how residential roofs are built. For metal roof shingles, it calls for a solid or closely fitted deck unless the product is specifically designed for spaced sheathing. A solid deck changes the sound of rain completely: the panel can no longer vibrate freely, and much of the impact energy goes into the deck instead of into the air.

If you have heard rain on a metal-roofed farm building in the Piedmont, that memory is accurate for that building. It just does not transfer to a house with a deck, attic and ceiling.

Rooms without an attic between the roof and the ceiling are the ones most likely to hear rain more clearly. Watch for these on your house:

• Vaulted and cathedral ceilings. With no attic, there may be only rafters, insulation and drywall between you and the deck. Good insulation helps a great deal here.
• Bonus rooms over garages. Common in Triangle and Charlotte homes, these often have sloped ceilings close to the roof on two or three sides.
• Screened porches and sunrooms. If the ceiling is open to the rafters or thinly finished, rain on any roof will be audible.
• Dormers and knee-wall rooms. Spaces tucked under the roof slope have less buffer than rooms under a full attic.

In these spaces, ask the contractor what will be under the metal. Solid decking, a quality underlayment and full insulation between the rafters all reduce sound. Some homeowners actually like hearing gentle rain on a porch roof, and a standing seam porch roof is often chosen partly for that reason. If you would rather not hear it, say so before the job is priced and scheduled.

Hail and heavy downpours are louder on any roof, and a metal roof is no exception. The National Weather Service defines a severe thunderstorm as one producing hail about 1 inch in diameter or wind gusts above 58 mph, and storms like that roll through the Piedmont in spring and summer. Hail on metal over a deck sounds sharper than hail on asphalt, but the attic and ceiling still buffer it, and storms that strong are noisy indoors no matter what is overhead because of the thunder and wind.

Tropical systems bring long periods of heavy rain rather than short bursts. NOAA's North Carolina climate summary describes Hurricane Florence dropping 20 to 36 inches of rain in eastern North Carolina in 2018. On a house, steady heavy rain on metal over a solid deck produces a muted, even sound, not the hammering of a barn roof.

If hail is your main worry, the bigger questions are damage and insurance rather than noise; see hail damage on NC roofs and roof insurance claims in NC.

Metal roofs can make occasional ticking or popping sounds as they warm up in the morning or cool down in the evening. Metal expands as it heats and contracts as it cools, and long panels that are held too tightly can shift with an audible tick. This is most common with long standing seam panels or exposed-fastener panels on large, sunny roof planes.

Shingle-style metal roofs are less prone to it because each panel is small and the movement is spread over many joints. North Carolina's summer heat, with roofs going from cool dawn temperatures to very hot afternoons, is exactly the kind of daily swing that reveals poor expansion detailing on long panels.

Wind can also cause noise if trim or flashing is loose. A rattle or flapping sound in wind is a sign that something needs refastening, and it should be fixed before the next big storm. See standing seam vs metal shingles for how the two systems handle expansion.

You keep a metal roof quiet by getting the layers under it right. The checklist is short:

• Solid decking. Replace any soft, delaminated or missing sheathing during the re-roof.
• Quality underlayment. Underlayment adds a cushioning layer between the metal and the deck as well as weather protection.
• Attic insulation. Insulation on the attic floor, or between rafters on vaulted ceilings, absorbs sound as well as heat. ENERGY STAR publishes recommended levels by climate zone.
• Proper fastening and trim. A tight installation with correctly fastened trim avoids rattles in wind.
• Expansion detailing. On long panels, clips that allow movement prevent ticking.

If you are replacing an old roof, tearing off the existing roof lets the crew inspect and repair the deck, which is good for both sound and durability. Our guide to metal over existing shingles explains when a layer can stay and when it cannot.

One thing that does not help much is choosing a thicker or heavier metal on its own. Panel weight matters far less than the deck and the layers beneath it. A light aluminum shingle fastened to a sound plywood deck is quieter than a heavier panel spanning open framing.

The surest way to settle the question is to listen to a finished residential metal roof, not a barn. Ask your contractor for addresses of completed homes, ideally ones with a room under a vaulted ceiling or a bonus room, and ask whether the owners mind a short visit, ideally on a rainy day. Compare it with what you hear under your own asphalt roof in a similar storm.

When you review estimates, ask each contractor to describe exactly what goes under the metal: decking repairs, underlayment type and any changes to insulation or ventilation. The answers tell you more about future noise than the roofing material does.

Metal Roof NC, an authorized Interlock aluminum roofing dealer, installs Interlock aluminum shingles and standing seam metal roofing over solid decks across the Triangle, Charlotte, the Triad and the coast. For more on the products, see metal shingles and aluminum roofing, or browse the service areas.