Why metal roofs are different
Metal roofing is smooth. Water runs off it faster than off asphalt shingles, which have a rough, granular surface that slows it down. This Old House notes that metal roofs shed water quickly, so a gutter system has to be properly sized and installed to handle the higher runoff and prevent overflow. The same smoothness means snow can slide off a metal roof all at once, in a heavy sheet, instead of melting gradually.
Both effects put gutters under more stress: more water arriving faster in storms, and occasional avalanches of snow and ice sliding directly into or over the gutter.
Gutter size: 6-inch is the common recommendation
Because water arrives faster, This Old House suggests 6-inch gutters rather than 5-inch on metal roofs. Pair them with 3x4-inch downspouts and plan enough outlets, especially near valleys where two roof planes send water to one corner. Our guide to 5-inch vs. 6-inch gutters explains how roof area, pitch and rainfall drive the choice.
Placement: catch the water without catching the snow
On a metal roof, gutter placement is a balancing act. This Old House advises mounting gutters high enough, because if they are too low, fast-moving water will overshoot them. At the same time, a gutter that sits too high in the path of sliding snow can be ripped off. Installers usually set the gutter so the roof panel overhangs into it enough to catch water, but low enough relative to the roof plane that sliding snow passes over rather than slamming into the gutter. Getting this right is a good reason to hire an installer with metal-roof experience.
Snow guards
In snow country, snow guards on the roof are often the most important protection for gutters under a metal roof. These small brackets or bars fastened to the roof hold snow in place so it melts gradually or slides off in smaller pieces. This Old House notes that snow guards slow sliding snow and break it into smaller chunks. That protects gutters, landscaping, decks and people below. Snow guards are usually part of the roofing work, so coordinate them with the roofer.
They matter most in places like Denver, where heavy spring snow slides off sunny roofs, and in Minneapolis–St. Paul, Boston and mountain areas with deep snowpacks.
Hangers and materials
- Hangers: hidden hangers at close spacing, about 2 feet apart in snow country according to Angi’s spacing guide, screwed into sound fascia and rafter tails. See gutter hangers explained.
- Gauge: heavier aluminum or steel resists dents from sliding ice.
- Compatible metals: avoid pairing metals that corrode each other where water runs from one to the other, such as copper roofing or flashing onto aluminum gutters. Tell the installer what your roof panels and flashing are made of. See gutter materials compared.
Gutter guards on metal roofs
Many guards are designed to slide under shingles, which does not work with metal panels. For metal roofs, look for guards that fasten to the gutter itself and to the fascia or drip edge, without penetrating or lifting the roof panels. Ask whether the guard can handle the faster water flow off metal, because some covers can overshoot in heavy rain even on shingle roofs.
Coordinating with the roofer
If you are replacing a shingle roof with metal, plan the gutters at the same time:
- Decide whether existing gutters are large enough; often they are not.
- Agree on the drip edge or trim detail at the eave and how the gutter will sit relative to it.
- Plan snow guards where snow could slide onto gutters, walks or entries.
- Schedule the gutter installer right after the roof panels and trim are finished.
Our guide to new roof, new gutters covers the sequence.
Standing seam vs. exposed-fastener panels
Metal roofs come in two main types. Standing seam roofs have raised seams with hidden fasteners and a clean edge; exposed-fastener (corrugated or ribbed) panels are screwed through the face. Both shed water quickly, but the edge details differ. On ribbed panels, water runs in the channels and can come off the eave in concentrated streams, which is another reason to size gutters generously and set them carefully. On standing seam, the eave trim and drip edge design decide where the gutter sits. Ask the installer to look at your panel profile before quoting.
Ice and cold climates
Metal roofs are often chosen in snowy regions because they shed snow. That shedding is good for the roof but hard on gutters. In addition to snow guards and close hanger spacing, consider where downspouts discharge in winter: water from a sunny metal roof can run into shaded downspouts and freeze. Larger downspouts and outlets on the sunnier sides help. See ice dams and gutters.
Inspect after the first winter
After the first winter with a new metal roof, walk around the house and look at every gutter run. Check for bent sections below areas where snow slid, loose hangers, and places where water overshot the gutter during spring rain. Small adjustments in the first year, such as adding a few snow guards or re-setting a section of gutter, prevent bigger damage later.
Common problems and fixes
- Water shoots over the gutter in storms: gutter set too low or too small; consider re-hanging higher and upsizing to 6-inch.
- Gutters bent or torn off in spring: sliding snow; add snow guards and heavier hangers.
- Overflow at valleys: add a downspout at the valley or a splash guard at the corner.
- Corrosion or staining: incompatible metals; check fasteners and flashing materials.
What it costs
| Project | Published range |
|---|---|
| Seamless aluminum gutters per linear foot, installed, national (HomeGuide) | $6 – $12 |
| Upgrade from 5-inch to 6-inch gutters (HomeGuide) | about $1 – $2 more per foot |
| Downspouts per linear foot, installed (HomeGuide) | about $2 – $4 |
Published figures for orientation only, not quotes. Snow guards are usually priced with the roofing work.