What size are normal gutters?
Short answer. The normal residential gutter is a 5-inch K-style aluminum gutter, paired with 2 by 3 inch or 3 by 4 inch downspouts. Six-inch K-style gutters are the common step up for larger or steeper roofs, and half-round gutters, usually 5 or 6 inches, appear mainly on historic or custom homes.
What the size measures
Gutter size is the width across the top opening. A 5-inch gutter is about 5 inches from back to front at the top. K-style gutters have a flat back and a decorative front that resembles crown molding; half-round gutters are a simple half circle.
The common combinations
- 5-inch K-style with 2 by 3 inch downspouts: the long-time standard on many tract homes.
- 5-inch K-style with 3 by 4 inch downspouts: same gutter, much better drainage, since a 3 by 4 opening is twice the area of a 2 by 3.
- 6-inch K-style with 3 by 4 inch downspouts: increasingly common on large, steep or complex roofs.
- Half-round, 5 or 6 inch, with round downspouts: chosen for looks on older or custom homes, usually in copper or aluminum.
Material thickness
Aluminum gutters are commonly made from .027 or .032 inch coil. The thicker coil resists dents from ladders and sagging under debris.
When normal is not enough
- Large roof planes draining to one run.
- Steep pitches, which deliver water faster.
- Valleys emptying into the gutter.
- Gutters that overflow in heavy rain even when clean.
North Georgia storms can drop a lot of rain quickly, so it pays to size for the hard downpours, not the average shower. See gutter sizing, seamless gutters and guards.