Roofing guide
What Size Gutters and Downspouts Atlanta Rain Needs
Clean gutters that still overflow are usually too small, or have too few downspouts, for the roof above them.
Talk to a roofer
A person answers any hour and can put a crew on the schedule while you are on the line.
Answered 24/7(470) 291-8924By Karl Sutton, Residential Roofing Writer · Updated September 2026
Gutter size in Atlanta depends on how much roof drains into each run, how steep it is, and whether valleys concentrate water at one corner. With about 50 inches of rain a year and single storms that can overwhelm standard gutters, steep roofs, long runs and pine-heavy lots usually need 6-inch gutters with 3 by 4 inch downspouts.
The problem
Why Clean Gutters Still Overflow
A gutter can only carry so much water, and a downspout can only drain so much. When a storm drops heavy rain on a large or steep roof, water arrives faster than a small system can move it and spills over the front.
Atlanta averages about 50 inches of rain a year, and a single storm can drop an inch of water, which is exactly when undersized gutters show it.
The factors
What Decides the Size
The area of roof draining into each run matters most. Steeper roofs send water faster, and valleys concentrate the flow from two slopes into one corner of the gutter.
Debris matters too. Under loblolly pines and sweetgums, larger downspouts pass needles and seed pods that jam smaller ones.
Sizes
5-Inch Versus 6-Inch Gutters
Standard 5-inch K-style gutters with 2 by 3 inch downspouts suit many single-story homes with short runs. Six-inch gutters with 3 by 4 inch downspouts carry noticeably more water and clog less.
On a two-story house with steep slopes and long runs, 6-inch is usually the right call, and the larger profile looks proportional to the house.
| 5-inch | 6-inch | |
|---|---|---|
| Downspouts | 2 by 3 inch | 3 by 4 inch |
| Best for | Short runs, low pitch | Steep roofs, long runs, heavy trees |
| Debris | Clogs sooner | Passes more |
Gutters overflowing even when clean? Call and we will measure the roof above each run.
Call nowOutlets
Downspouts Matter as Much as Gutters
A large gutter with one downspout at the far end still overflows. Long runs need more outlets, and corners where valleys dump water need their own.
Where the downspout empties matters too. In Atlanta's slow-draining clay, water left at the foundation tends to sit there, so extensions or buried drain lines should carry it away.
Timing
When to Resize at Replacement
The cheapest time to upsize gutters is during a roof replacement, when the old gutters come down anyway and new drip edge goes on.
If only one side overflows, resizing that run or adding a downspout may be enough. A gutter visit shows which runs are undersized.
Warning signs
Signs Your Gutters Are Undersized
Water spilling over the front during heavy rain even right after a cleaning, sheets of water pouring off one corner below a valley, and splash lines or mud on the lower siding all point to a gutter or downspout that cannot keep up.
Look under the eaves after a storm too. A worn trench in the soil below the gutter shows exactly where the overflow lands.
Guards
Guards and Size Work Together
Gutter guards keep debris out, but they do not add capacity. On an undersized system, a guard can even shed water over the edge in a downpour.
Size the gutters and downspouts for the roof first, then choose a guard matched to the trees overhead. That order gives you a system that stays clear and still carries the water.
FAQ
Short Answers to Common Questions
On steep roofs, long runs and pine-heavy lots, usually yes.
Often a valley concentrates water there, or the downspout is too small or clogged.
Yes. Adding outlets on long runs often solves overflow without replacing the gutters.
Larger downspouts pass more debris, so the whole system clogs less.
They keep debris out, but they do not add capacity to an undersized gutter.
Away from the foundation, onto a splash block, an extension or a buried drain line.
If they are old or undersized, yes. They come down during the replacement anyway.
Related
What to Read Next
Gutter Installation
Seamless Aluminum Gutters and 6-inch oversized gutters.
See the service →Downspout Drain Line Installation
Buried Downspout Drain Lines and pop-up emitters and daylight outlets.
See the service →Gutter Cleaning
Gutter and Downspout Flushing and underground drain clearing.
See the service →Atlanta, GA service office
1421 Peachtree St NE FL. 3, Atlanta, GA 30361
Talk to a roofer today
Size the gutters to the roof
Call to book a gutter visit. We measure the roof above each run and quote the size and outlets that will carry the water.