What size gutters are standard?
What the numbers mean
The size of a K-style gutter refers to the approximate width across the top opening. A 6-inch gutter holds substantially more water than a 5-inch one, because both the width and depth increase. Downspout sizes refer to the rectangular cross section: 2 by 3 inches for standard, 3 by 4 inches for high capacity. A 3 by 4 inch downspout carries roughly twice the water of a 2 by 3 and clogs far less often.
When 5-inch is enough
- Moderate pitch roofs with average-size roof planes.
- Runs that are not too long, with downspouts at reasonable spacing.
- Few valleys pouring into a single corner.
When 6-inch is the better standard
- Steep roofs, which deliver water faster.
- Large roof planes draining into one gutter.
- Long runs or limited downspout locations.
- Valleys concentrating water at inside corners.
- Metal roofs.
- Any house where clean 5-inch gutters overflow in hard rain.
Why Georgia leans larger
Georgia's warm-season thunderstorms bring short bursts of very heavy rain. Gutters are sized for those peaks, not for a typical drizzle, so moving from 5-inch to 6-inch on big or steep roof planes and using 3 by 4 inch downspouts is a common and sensible upgrade. Coil thickness matters too; thicker aluminum resists dents and sagging. More in our guide to gutter sizing and seamless gutters and how roofers measure a roof.